Dissertations / Theses: 'Lignocellulose'

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Warsame, Mohamed. "Saccharification of lignocellulose." Thesis, Malmö högskola, Fakulteten för hälsa och samhälle (HS), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-25910.

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Den ökande efterfrågan på energi och den förväntade nedgången i råoljeproduktion har lett till ett enormt sökande efter nya energikällor.Cellväggen i växter består till stor del av lignocellulosa som i sin tur innehåller cellulosa och hemicellulosa. Dessa polysackarider är av stor betydelse för sökandet efter förnyelsebar energi.Cellväggen måste förbehandlas innan den kan brytas ner till enkla sockerarter. Efter nedbrytning kan monosackariderna användas till produktion av etanol eller biogas genom väl etablerade fermenteringstekniker. Syftet med denna studie var att jämföra och utvärdera några metoder som används vid degradering av lignocellulosa. Tre behandlingar har jämfört för att se vilken som ger mest avkastning i form av monosackarider. Vetehalm användes som substrat och hydrolyseras med hjälp av tre kommersiella enzymblandningar. Proverna förbehandlades före den enzymatiska reaktionen med antingen mikrovågor eller ångexplosion.Resultaten visade att en behandling med mikrovågsbestrålning eller ångexplosion kombinerad med enzymhydrolys gav högst avkastning. De slutsatser som kan dras är att en mekanisk förbehandling ökar utbytet drastiskt men är otillräcklig i sig. Ytterligare enzymatisk behandling är nödvändig att erhålla större mängder enkla sockerarter från lignocellulosa.
The increasing energy demand and the anticipated decline in crude oil production has led to an immense search for new energy sources. Plant cell walls contain lignocellulose that conserve great amounts of energy. These polysaccharides are of high importance for the search of renewable energy sources. Pretreatment of the cell wall is necessary in order to hydrolyse it to its component sugars. Once degraded to monomeric sugars it can be fermented to either ethanol or biogas through established fermentation technologies.The aim of this thesis was to compare and evaluate some of the methods used for sacchrification of lignocellulose. Three treatments where compared to determine which is highest yielding. These are enzymatic hydrolysis, microwave irradiation and steam explosion.Wheat straw was used as substrate and hydrolysed by three commercial enzyme mixtures. Samples were pretreated before the enzymatic reaction with either microwave or steam explosion. Results showed that a treatment of either microwave irradiation or steam explosion combined with enzyme hydrolysis gives the highest yield in monomeric sugars. The conclusions that can be drawn are that mechanical pretreatment increases yield drastically but is insufficient in its self. Further enzymatic treatment of wheat straw is necessary to obtain high amounts of simple sugars.

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Garcia, Susana. "Biodégradation des lignocelluloses : étude microbiologique, physiologique et ultrastructurale." Paris 7, 1988. http://www.theses.fr/1988PA077057.

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Étude de l'optimisation de la ligninolyse par fermentation mixte de phanérochaète chrysosporium sur des substrats naturels. Puis étude des mécanismes de la dégradation de la lignine et mise en évidence du rôle des enzymes impliquées : la ligninase et la péroxydase.

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Keränen, A. (Anni). "Water treatment by quaternized lignocellulose." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526215143.

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Abstract Water-related problems are increasing globally, and new, low-cost technologies are needed to resolve them. Lignocellulosic waste materials contain reactive functional groups that can be used to provide a bio-based platform for the production of water treatment chemicals. Research on bio-based ion exchange materials in the treatment of real wastewaters is needed. In this thesis, anion exchange materials were prepared through chemical modification (epichlorohydrin, ethylenediamine and triethylamine) using five Finnish lignocellulosic materials as bio-based platforms. Scots pine sawdust and bark (Pinus sylvestris), Norway spruce bark (Picea abies), birch bark (Betula pendula/pubescens) and peat were chosen due to their local availability and abundance. The focus was placed on NO3- removal, but uptake of heavy metals, such as nickel, was also observed and studied. Studies on maximum sorption capacity, mechanism, kinetics, and the effects of temperature, pH and co-existing anions were used to elucidate the sorption behaviour of the prepared materials in batch and column tests. All five materials removed over 70% of NO3- at pH 3–10 (initial conc. 30 mg N/l). Quaternized pine sawdust worked best (max. capacity 32.8 mg NO3-N/g), and also in a wide temperature range (5–70°C). Column studies on quaternized pine sawdust using mining wastewater and industrial wastewater from a chemical plant provided information about the regeneration of exhausted material and its suitability for industrial applications. Uptake of Ni, V, Co and U was observed. Column studies proved the easy regeneration and reusability of the material. For comparison, pine sawdust was also modified using N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride and utilized to remove NO3- from groundwater and industrial wastewater. A maximum sorption capacity of 15.3 mg NO3-N/g was achieved for the synthetic solution. Overall, this thesis provides valuable information about bio-based anion exchange materials and their use in real waters and industrial applications
Tiivistelmä Edullisia ja kestäviä vedenkäsittelytekniikoita tarvitaan kasvavien vesiongelmien ratkaisemiseen. Lignoselluloosaa, kuten sahanpurua, syntyy suuria määriä teollisuuden sivutuotteena. Sen reaktiivisia funktionaalisia ryhmiä voidaan modifioida kemiallisesti ja valmistaa siten biopohjaisia vedenkäsittelykemikaaleja. Tutkimustietoa oikeiden jätevesien puhdistuksesta biopohjaisilla ioninvaihtomateriaaleilla tarvitaan lisää, jotta materiaalien käyttöä voidaan kehittää ja edistää. Tässä väitöstyössä valmistettiin anioninvaihtomateriaaleja modifioimalla kemiallisesti viittä suomalaista lignoselluloosamateriaalia: männyn sahanpurua ja kuorta (Pinus sylvestris), kuusen kuorta (Picea abies), koivun kuorta (Betula pendula/pubescens) ja turvetta. Menetelmässä käytettiin epikloorihydriiniä, etyleenidiamiinia ja trietyyliamiinia orgaanisessa liuotinfaasissa. Työssä keskityttiin erityisesti nitraatin poistoon sekä synteettisistä että oikeista jätevesistä. Materiaalien soveltuvuutta teollisiin sovelluksiin arvioitiin maksimisorptiokapasiteetin, sorptioisotermien, kinetiikka- ja kolonnikokeiden sekä pH:n, lämpötilan ja muiden anionien vaikutusta tutkivien kokeiden avulla. Kaikki viisi kationisoitua tuotetta poistivat yli 70 % nitraatista laajalla pH-alueella (3–10). Kationisoitu männyn sahanpuru osoittautui parhaaksi materiaaliksi (32,8 mg NO3-N/g), ja se toimi laajalla lämpötila-alueella (5–70°C). Kolonnikokeet osoittivat sen olevan helposti regeneroitavissa ja uudelleenkäytettävissä. Tuotetta testattiin myös kaivos- ja kemiantehtaan jäteveden käsittelyyn, ja kokeissa havaittiin hyviä nikkeli-, uraani-, vanadiini- ja kobolttireduktioita. Männyn sahanpurua modifioitiin vertailun vuoksi myös kationisella monomeerilla, N-(3-kloro-2-hydroksipropyyli)trimetyyliammoniumkloridilla. Tuotteen maksimisorptiokapasiteetiksi saatiin 15,3 mg NO3-N/g ja se poisti nitraattia saastuneesta pohjavedestä. Kokonaisuudessaan väitöskirjatyö tarjoaa uutta tietoa biopohjaisten ioninvaihtomateriaalien valmistamisesta ja niiden soveltuvuudesta oikeiden teollisuusjätevesien käsittelyyn

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Van, Dyk Jacoba Susanna. "Characterisation of the cellulolytic and hemicellulolytic system of Bacillus Licheniformis SVD1 and the isolation and characterisation of a multi-enzyme complex." Thesis, Rhodes University, 2009. http://hdl.handle.net/10962/d1003995.

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The biological degradation of lignocellulose into fermentable sugars for the production of liquid transportation fuels is feasible and sustainable, but equires a variety of enzymes working in synergy as lignocellulose is a complex and recalcitrant substrate. The cellulosome is a multi-enzyme complex (MEC) with a variety of cellulolytic and hemicellulolytic enzymes that appears to facilitate an enhanced synergy and efficiency, as compared to free enzymes, for the degradation of recalcitrant substrates such as lignocellulose and plant cell walls. Most of the studies on cellulosomes have focused on a few organisms; C. thermocellum, C. cellulovorans and C. cellulolyticum, and there is only limited knowledge vailable on similar complexes in other organisms. Some MECs have been identified in aerobic bacteria such as Bacillus circulans and Paenibacillus curdlanolyticus, but the nature of these MECs have not been fully elucidated. This study investigated the cellulolytic and emi-cellulolytic system of Bacillus licheniformis SVD1 with specific reference to the presence of a MEC, which has never been reported in the literature for B. licheniformis. A MEC of approximately 2,000 kDa in size, based on size exclusion chromatography using Sepharose 4B, was purified from a culture of B. licheniformis. When investigating the presence of enzyme activity in the total crude fraction as well as the MEC of a birchwood xylan culture, B. licheniformis was found to display a variety of enzyme activities on a range of substrates, although xylanases were by far the predominant enzyme activity present in both the crude and MEC fractions. Based on zymogram analysis there were three CMCases, seven xylanases, three mannanases and two pectinases in the crude fraction, while the MEC had two CMCases, seven xylanases, two mannanases and one pectinase. The pectinases in the crude could be identified as a pectin methyl esterase and a lyase, while the methyl esterase was absent in the MEC. Seventeen protein species could be detected in the MEC but only nine of these displayed activity on the substrates tested. The possible presence of a β-xylosidase in the crude fraction was deduced from thin layer chromatography (TLC) which demonstrated the production of xylose by the crude fraction. It was furthermore established that B. licheniformis SVD1 was able to regulate levels of enzyme expression based on the substrate the organism was cultured on. It was found that complexed xylanase activity had a pH optimum of between pH 6.0 and 7.0 and a temperature optimum of 55oC. Complexed xylanase activity was found to be slightly inhibited by CaCl2 and inhibited to a greater extent by EDTA. Complexed xylanase activity was further shown to be activated in the presence of xylose and xylobiose, both compounds which are products of enzymatic degradation. Ethanol was found to inhibit complexed xylanase activity. The kinetic parameters for complexed xylanase activity were measured and the Km value was calculated as 2.84 mg/ml while the maximal velocity (Vmax) was calculated as 0.146 U (μmol/min/ml). Binding studies, transmission electron microscopy (TEM) and a bioinformatic analysis was conducted to investigate whether the MEC in B. licheniformis SVD1 was a putative cellulosome. The MEC was found to be unable to bind to Avicel, but was able to bind to insoluble birchwood xylan, indicating the absence of a CBM3a domain common to cellulosomal scaffoldin proteins. TEM micrographs revealed the presence of cell surface structures on cells of B. licheniformis SVD1 cultured on cellobiose and birchwood xylan. However, it could not be established whether these cell surface structures could be ascribed to the presence of the MECs on the cell surface. Bioinformatic analysis was conducted on the available genome sequence of a different strain of B. licheniformis, namely DSM 13 and ATCC 14580. No sequence homology was found with cohesin and dockerin sequences from various cellulosomal species, indicating that these strains most likely do not encode for a cellulosome. This study described and characterised a MEC that was a functional enzyme complex and did not appear to be a mere aggregation of proteins. It displayed a variety of hemi-cellulolytic activities and the available evidence suggests that it is not a cellulosome, but should rather be termed a xylanosome. Further investigation should be carried out to determine the structural basis of this MEC.

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Qin, Wenjuan. "High consistency enzymatic hydrolysis of lignocellulose." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/24374.

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The work described in this thesis focused on the development of a practical, high consistency hydrolysis and fermentation processes utilizing existing pulp mill equipment. Carrying out enzymatic hydrolysis at high substrate loading provided a practical means of reducing the overall cost of a lignocellulose to ethanol bioconversion process. A laboratory peg mixer was used to carry out high consistency hydrolysis of several lignocellulosic substrate including an unbleached hardwood pulp (UBHW), an unbleached softwood pulp (UBSW), and an organosolv pretreated poplar (OPP) pulp. Enzymatic hydrolysis of OPP for 48 hours resulted in a hydrolysate with a glucose content of 158 g/L. This is among the highest glucose concentration reported for the enzymatic hydrolysis of lignocellulosic substrates. The fermentation of UBHW and OPP hydrolysates with high glucose content led to high ethanol concentrations in the final fermentation broth (50.4 and 63.1 g/L, respectively). These values were again as high as any values reported previously in the literature. To overcome end-product inhibition caused by the high glucose concentration resulting from hydrolysis at high substrate concentration, a new hydrolysis and fermentation configuration, (liquefaction followed by simultaneous saccharification and fermentation (LSSF)), was developed and evaluated using the OPP substrate. Applying LSSF led to a production of 63 g/L ethanol from OPP. The influence of enzyme loading and β-glucosidase addition on ethanol yield from the LSSF process was also investigated. It was found that, at higher enzyme loading (10FPU or higher), the ethanol production from LSSF was superior to that of the SHF process. It was apparent that the LSSF process could significantly reduce end-product inhibition when compared to a Separate Hydrolysis and Fermentation (SHF) process. It was also apparent that β-glucosidase addition was necessary to achieve efficient ethanol production when using the LSSF process. A 10CBU β-glucosidase supplement was enough for the effective conversion of the 20% consistency OPP by LSSF. The rheological property change of the different substrates at the liquefaction stage was also examined using the rheometer technique. The use of a fed-batch hydrolysis process to further improve the high consistency hydrolysis efficiency was also assessed.

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Bi, Ran. "Lignocellulose Degradation by Soil Micro-organisms." Doctoral thesis, KTH, Träkemi och massateknologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-182336.

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Lignocellulosic biomass is a sustainable resource with abundant reserves. Compared to petroleum ‐ based products, the biomass ‐ derived polymers and chemicals give better environmental profiles. A lot of research interest is focused on understanding the lignocellulose structures. Lignin, among the three major wood components, represents most difficulty for microbial degradation because of its complex structure and because cross ‐ linking to hemicellulose makes wood such a compact structure. Nevertheless, wood is naturally degraded by wood ‐ degrading micro ‐ organisms and modified and partly degraded residual of lignin goes into soil. Therefore soil serves as a good environment in which to search for special lignin ‐ degraders. In this thesis, different types of lignin have been used as sole carbon sources to screen for lignin ‐ degrading soil micro ‐ organisms. Eleven aerobic and three anaerobic microbe strains have been isolated and identified as able to grow on lignin. The lignin degradation patterns of selected strains have been studied and these partly include an endwise cleavage of β‐ O ‐ 4 bonds in lignin and is more complex than simple hydrolytic degradation. As lignin exists in wood covalently bonded to hemicellulose, one isolated microbe strain, Phoma herbarum, has also been studied with regards to its ability to degrade covalent lignin polysaccharide networks (LCC). The results show that its culture filtrate can attack lignin ‐ polysaccharide networks in a manner different from that of the commercial enzyme product, Gammanase, possibly by selective cleavage of phenyl glucoside bonds. The effects on LCC of Phoma herbarum also enhance polymer extractability. Hot ‐ water extraction of a culture filtrate of Phoma herbarum ‐ treated fiberized spruce wood material gave an amount of extracted galactoglucomannan more than that given by the Gammanase ‐ treated material and non ‐ enzyme ‐ treated material. Over millions of years of natural evolution, micro ‐ organisms on the one hand develop so that they can degrade all wood components to get energy for growth, while plants on the other hand also continuously develop to defend from microbial attack. Compared with lignin and cellulose, hemicelluloses as major components of plant cell walls, are much more easily degraded, but hemicelluloses differ from cellulose in that they are acetylated to different extents. The biological functions of acetylation are not completely understood, but it is suggested is that one function is to decrease the microbial degradability of cell walls. By cultivation of soil micro ‐ organisms using mannans acetylated to deffernent degrees as sole carbon source on agar plates, we were able to see significant trends where the resistance towards microbial degradation of glucomannan and galactomannan increased with increasing degree of acetylation. Possible mechanisms and the technological significance of this are discussed. Tailoring the degree of acetylation of polysaccharide materials might slow down the biodegradation, making it possible to design a material with a degradation rate suited to its application.

QC 20160223

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Mamphogoro, Tshifhiwa Paris. "Laccases from actinomycetes for lignocellulose degradation." Thesis, University of the Western Cape, 2012. http://hdl.handle.net/11394/3945.

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>Magister Scientiae - MSc
The purpose of this study shows that lignocellulose has a complex structure composed mainly of lignin, hemicellulose and cellulose. Several enzymes are needed for the degradation of lignocellulose into simple sugars. Actinomycetes are known to produce laccases which are able to degrade lignin. Laccase activities were detected in actinomycete strains MS26 isolated from soil collected from the Zambian Copperbelt and DFNR17 isolated from soil collected from a New Zealand farm. Morphological studies showed that the strains produced extensively branched substrate mycelia and aerial hyphae. Micromorphological characteristics were consistent with the assignment of these strains to the genus Streptomyces. Isolates were found to be mesophiles, with growth occurring in a temperature range of 16 and 45°C. Optimal growth occurred at temperatures between 30 and 37oC. Analysis of the 16S rRNA gene sequences of the strains showed that strain MS26 had the highest sequence similarity (99%) to Streptomyces atrovirens strain NRRL B-16357 and Streptomyces viridodiastaticus strain IFO 13106. Strain DFNR17 had the highest 16S rRNA gene sequence similarity (99%) to Streptomyces althioticus strain KCTC 9752. The strains shared several physiological and biochemical characteristics with their closest neighbours which, along with 16S rRNA gene sequences analysis, confirmed that the strains were members of the genus Streptomyces. Attempts to identify the laccase genes from these isolates by screening a fosmid library failed. Subsequently isolates were screened by PCR using laccase-like cooper oxidase degenerate primers designed from several Streptomyces strains. A 300 bp amplicon was obtained from both isolates. Phylogenetic analysis was performed and both amplicons from strains MS26 and DFNR17 had the highest similarities with the copper oxidase gene from Streptomyces griseoflavus strain Tu4000. Therefore it is probable that the laccase activity observed for these strains is due to the activity of copper oxidase gene product

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Moxley, Geoffrey W. "Studies of Cellulosic Ethanol Production from Lignocellulose." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/43372.

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At present, the worldâ s transportation sector is being principally supplied by fossil fuels. However, energy consumption in this sector is drastically increasing and there are concerns with supply, cost, and environmental issues with the continuing use of fossil fuels. Utilizing non-petroleum ethanol in the transportation sector reduces the dependence on oil, and allows for cleaner burning of gasoline.

Lignocellulose materials are structurally composed of five types of polymeric sugars, glucan, galactan, mannan, arabinan, and xylan. NREL has developed a quantitative saccharification (QS) method for determining carbohydrate composition. We proposed a new protocol based on the NREL 2006 Laboratory Analytical Procedure â Determination of Structural Carbohydrates and Lignin in Biomassâ (Sluiter et al. 2006a) with a slight modification, in which xylose concentration was determined after the secondary hydrolysis by using 1% sulfuric acid rather than 4% sulfuric acid. We found that the current NREL protocol led to a statistically significant overestimation of acid-labile xylan content ranging from 4 to 8 percent.

Lignocellulosic biomass is naturally recalcitrant to enzymatic hydrolysis, and must be pretreated before it can be effectively used for bioethanol production. One such pretreatment is a fractionation process that separates lignin and hemicellulose from the cellulose and converts crystalline cellulose microfibrils to amorphous cellulose. Here we evaluated the feasibility of lignocellulose fractionation applicable to the hurds of industrial hemp. Hurds are the remaining material of the stalk after all leaves, seeds, and fiber have been stripped from the plant. After optimizing acid concentration, reaction time and temperature, the pretreated cellulosic samples were hydrolyzed to more than 96% after 24 hours of hydrolysis (enzyme loading conditions of 15 FPU/g glucan Spezyme CP and 60 IU/g glucan Novozyme 188) at the optimal pretreatment condition (> 84% H3PO4, > 50 Â°C and > 1 hour). The overall glucose and xylose yields were 89% (94% pretreatment; 96% digestibility) and 61%, respectively. All data suggest the technical feasibility of building a biorefinery based on the hurds of industrial hemp as a feedstock and a new lignocellulose fractionation technology for producing cellulosic ethanol. The choice of feedstock and processing technology gives high sugar yields, low processing costs, low cost feedstock, and low capital investment.
Master of Science

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Clarke, Anna Maria. "The microbial ecology of sulphidogenic lignocellulose degradation." Thesis, Rhodes University, 2007. http://hdl.handle.net/10962/d1008181.

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Acid mine drainage is a well known environmental pollutant, not only in South Africa, but throughout the world, and the use of microbial processes in the treatment of these wastes has been the subject of investigation over past decades. Lignocellulose packed-bed reactors have been used in passive treatment systems, and, although effective initially, they show early decline in performance while the packing material remains largely un-utilized. Little is known about this phenomenon which remains a severe constraint in the development of efficient passive mine water treatment systems. It has been proposed that the degradation pathways of the complex lignocellulose substrate may be limited in some way in these systems during the manifestation of this effect. This study has addressed the problem using a molecular microbial ecology methodology in an attempt to relate trophic functions of the microbial population to the physico-chemical data of the system. A field-scale lignocellulose packed-bed reactor located at Vryheid Coronation Colliery (Northern Kwa-Zulu Natal province, South Africa) was monitored for six years and the results showed the classic profile of performance decline related to a slowdown in sulphate reduction and alkalinity production. The reactor was decommissioned , comprehensive samples were collected along the depth profile and the microbial populations investigated by means of 16S rRNA gene methodology. The population was found to include cellulolytic Clostridia spp., CytophagaIFlavobacterlBacteroidetes, Sphingomonadaceae and as yet uncultured microorganisms related to microbiota identified in the rumen and termite gut. These are all known to be involved as primary fermenters of cellulose. Oesulphosporosinus was present as sulphate reducer. A comparison of substrata sampling and population distribution suggested that spatial and temporal gradients within the system may become established over the course of its operation. Based on these findings, a laboratory-scale reactor was constructed to simulate the performance of the packed-bed reactor under controlled experimental conditions. The laboratory-scale reactor was operated for 273 days and showed comparable performance to that in the field in both biomolecular and physicochemical data. Clearly defined trophic niches were observed. These results suggested that a sequence of events does occur in lignocellulose degradation over time. Based on the spatial and temporal column studies, a descriptive model was proposed to account for these events. It was found that fermentative organisms predominate in the inlet zone of the system using easily extractable compounds from the wood, thus providing feedstock for sulphate reduction occurring in the succeeding compartments. Production of sulphide and alkalinity appears to be involved in the enhancement of lignin degradation and this, in turn, appears to enhance access to the cellulose fraction. However, once the readily extractables are exhausted, the decline in sulphide and alkalinity production leads inexorably to a decline in the overall performance of the system as a sulphate reducing unit operation. These observations led to the proposal that with the addition of a limited amount of a readily available carbon source, such as molasses, in the initial zone of the the reactor, the ongoing generation of sulphide would be sustained and this in turn would sustain the microbial attack on the lignocellulose complex. This proposal was tested in scale-up studies and positive results indicate that the descriptive model may, to some extent, provide an account of events occurring in these systems. The work on sustaining lignocellulose degradation through the maintenance of sulphate reduction in the initial stages of the reactor flow path has led to the development of the Degrading Packed-bed Reactor concept and that, has subsequently been successfully evaluated in the field.

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icardi, sara. "Lignocellulose degradation: a proteomic and metagenomic study." Doctoral thesis, Università del Piemonte Orientale, 2018. http://hdl.handle.net/11579/97185.

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Wood decay processes have recently attracted so much attention, as lignocellulose biomass (LCB) represents the most abundant renewable resource on the Earth and can provide fermentable sugar monomers convertible into value-added products. In order to improve the efficiency and ecological sustainability of the process, new insights about lignocellulosic biomass microbial degradation could be of fundamental importance. Organic matter rich environmental samples may host a large variety of microbes, most of them specialized in the degradation of LCB and thus important as potential sources of biochemical catalysts for value added products production, as well as for the global carbon cycle. The aim of this thesis is to study the LCB degradation by two different approaches, exploiting proteomic and metagenomic tools. Proteomic analyses were conducted on the secretomes of a bacterium, Cellulomonas fimi, grown in presence of carboxymethyl-cellulose or different pretreated LCBs as unique carbon sources. Zymography and enzyme activity assays confirmed the lignocellulose degrading capabilities of C. fimi, showing endoglucanase and xylanase activities. The comparison among secretomes (in terms of enzymatic activities and protein composition) obtained after growth on different substrates highlighted: i) the major proteins and CAZymes (Carbohydrate Active enZymes) secreted and involved in LCB degradation and ii) the substrate influence on the secretome protein composition and enzymatic activity. Metagenomic analyses were indeed conducted on two groups of representative samples (two decaying woods and two control soils) in order to characterize the microbial communities inhabiting them. The microorganisms (bacteria and fungi) found to be more represented in decaying wood samples than in soils could be considered the most probably responsible for wood degradation.

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Cheng, Wei. "Pretreatment and enzymatic hydrolysis of lignocellulosic materials." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1951.

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Thesis (M.S.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains xii, 173 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 138-142).

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Trento, Alberto. "Selection and genetic improvement of yeasts for the conversion of lignocellulose into second generation bioethanol." Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3422640.

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Bioethanol produced from lignocellulosic biomass represents a promising alternative among biofuels. To date a cost-effective method for the industrial production of bioethanol from vegetal biomass has not been developed. One of the most attractive strategies is the construction of a CBP (Consolidated BioProcessing) microbe able both to hydrolyze the complex polymers of lignocellulosic biomass and to convert these into ethanol. In this context, the present study focused on the development of an industrial CBP microbe for the conversion of cellobiose into ethanol. To this purpose, it was necessary to define a new screening method for the selection of a yeast strain, suitable for the industrial bioethanol production having high fermentative abilities and considerable tolerance to inhibitors commonly present in lignocellulosic hydrolysates. The selection started from a collection of oenological yeasts. These strains, although showing interesting fermentative abilities, did not exhibit a good tolerance to inhibitors such as furfural, acetic acid, formic acid and lactic acid. Therefore, a new isolation programme was necessarily conducted in order to select efficient fermenting yeast strains able to tolerate high concentrations of inhibitory compounds. The isolation procedure, conducted in the presence of an inhibitors cocktail, allowed to obtain a wide collection of yeasts with interesting features for their future applications in the field of second generation bioethanol. Among them, few S. cerevisiae yeasts exhibited remarkable fermenting vigour at high temperature and promising inhibitors tolerance. In particular, S. cerevisiae T2 was selected as host for the development of a recombinant strain able to produce the BglI β-glucosidase of Saccharomycopsis fibuligera, one of the most efficient cellobiose hydrolyzing yeast species. For the first time, in this study, an industrial yeast strain secreting β-glucosidase BglI was described. However, the hydrolytic activity of the recombinant strain must be necessarily increased in order to produce an efficient cellulolytic CBP microbe. On the basis of the preliminary results obtained, this multi-disciplinary work represents a first step towards the development of microbes for the single-step conversion of lignocellulosic biomass to ethanol.
Il bioetanolo di origine lignocellulosica rappresenta una delle alternative più promettenti tra i biocarburanti. Dal punto di vista industriale, la produzione di bioetanolo da biomassa vegetale non è ancora sostenibile. Una delle strategie più interessanti proposte è la costruzione di un microganismo CBP (Consolidated BioProcessing) capace di idrolizzare i polimeri complessi della biomassa cellulosica e di convertirli efficacemente in etanolo. In questa prospettiva, questo lavoro di tesi si è focalizzato sullo sviluppo di un microbo CBP di tipo industriale per la conversione di cellobiosio in alcol etilico. A tal scopo, è stato necessario mettere a punto un nuovo metodo per la selezione di un ceppo di lievito idoneo alla produzione di bioetanolo su scala industriale caratterizzato da elevate performance fermentative e da una notevole capacità di tollerare gli inibitori normalmente presenti negli idrolizzati lignocellulosici. La selezione di tale microrganismo è partita da una collezione di ceppi di lievito di origine enologica. I ceppi enologici saggiati, pur dimostrando elevate capacità fermentative, non si sono purtroppo rivelati tolleranti nei confronti di inibitori quali furfurale, acido acetico, acido formico ed acido lattico. È stato quindi necessario eseguire un programma di isolamento mirato ad ottenere ceppi di lievito altamente fermentanti e capaci di tollerare elevate concentrazioni di inibitori. L’isolamento, eseguito in condizioni selettive per la presenza di un cocktail di inibitori, ha consentito di ottenere una ampia ceppoteca di lieviti con caratteristiche promettenti per la loro futura applicazione nel campo del bioetanolo di seconda generazione. Tra di essi, alcuni lieviti S. cerevisiae si sono distinti per vigore fermentativo ad elevata temperatura e per una consistente tolleranza agli inibitori. In particolare, il ceppo S. cerevisiae T2 è stato selezionato come host strain per lo sviluppo di un ceppo ricombinante capace di secernere la betaglucosidasi BglI di Saccharomycopsis fibuligera, specie di lievito tra le più efficienti per l’idrolisi del cellobiosio. Per la prima volta in questo lavoro di tesi è stato descritto un ceppo di lievito industriale betaglucosidasico. In ogni caso, l’attività idrolitica del ceppo ricombinante dovrà essere necessariamente incrementata al fine di ottenere un efficiente microrganismo CBP cellulosolitico. In base ai risultati ottenuti, questo studio rappresenta un primo passo verso lo sviluppo di microrganismi idonei alla conversione one-step di biomassa lignocellulosica in etanolo.

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13

Oates, Nicola Claire. "Mining microbial compost communities for lignocellulose degrading proteins." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/18352/.

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The production of second generation biofuels from agricultural residues is an attractive alternative to the use of conventional first generation feedstocks, which are also important food resources. However, these alternative feedstocks predominately consist of lignocellulose, the main structural component of the plant cell wall, and expensive physicochemical and enzymatic pre-treatments are required before fermentation into biofuel. Therefore, the discovery of novel enzymes capable of deconstructing lignocellulose, in conditions that would be amenable to industry, is an important goal. The work, presented in this thesis, has explored the degradation of lignocellulose by a community of composting microbes, enriched for growth on wheat straw. Culturable members of the community, were isolated and assessed for their enzymatic activities towards lignin, cellulose and xylan. From these studies, a promising Ascomycota was identified, Graphium sp., which was capable of utilising both crystalline cellulose and xylan as carbon sources for growth. Transcriptomic studies were performed on Graphium sp. with and without wheat straw present, representing the first molecular information generated from an organism of this genus. From this 680 putative proteins were annotated as containing carbohydrate active domains. Proteomics added further depth to the analysis, with investigations focused on secreted proteins both located in the culture supernatant and bound to the insoluble lignocellulose substrate. Six secreted proteins were identified as targets for further analysis, and three of these were successfully isolated either from the native host, or a heterologous system. This included a lytic polysaccharide monooxygenase that appeared active on both chitin and cellulose, and a GH7 whose activity on cellulose was demonstrated. An intriguing protein, which showed low homology to a dioxygenase, was also expressed, though its role in the lignocellulose degrading environment has yet to be established.

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Chen, Shou-Feng Chambliss C. Kevin. "High-performance liquid chromatographic methods for quantitative assessment of degradation products and extractives in pretreated lignocellulose." Waco, Tex. : Baylor University, 2007. http://hdl.handle.net/2104/5129.

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Du, Bowen Chambliss C. Kevin. "Effect of varying feedstock-pretreatment chemistry combinations on the production of potentially inhibitory degradation products in biomass hydrolysates." Waco, Tex. : Baylor University, 2009. http://hdl.handle.net/2104/5319.

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16

Zahedifar, Mojtaba. "Novel uses of lignin and hemicellulosic sugars from acid-hydrolysed lignocellulosic materials." Thesis, University of Aberdeen, 1996. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=195786.

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Lignocellulosic materials (LM) are an ever present renewable and available energy source. The energy stored by photosynthesis in the form of vegetation is about ten times more than world's annual energy consumption (Zsuffa, 1982). This source is the only alternative for chemical production after fossil fuels. Formation of organic acids (mainly acetic acid) from hemicellulose during steam treatment of LM leads to acid hydrolysis of cell wall components. Solubilization of hemicellulose and depolymerization of lignin are the most important changes that occur during the process. During hydrolysis of LM appreciable amounts of sugar degradation products, organic acids and phenolics are produced. Inhibitory effects of the compounds on yeast during alcoholic fermentation have been reported and several methods have been proposed to overcome the problem. Among the new compounds phenolics derived from lignin depolymerization have received most attention. Another problem during enzymic saccharification of cellulose is partial inactivation of cell free enzymes. The above mentioned constraints were investigated in this study.

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17

Lazuka, Adele. "Production de synthons par des consortia microbiens à partir de paille de blé : approches macrocinétique, enzymatique et métaprotéomique." Thesis, Toulouse, INSA, 2018. http://www.theses.fr/2018ISAT0049.

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Alors que la biomasse lignocellulosique constitue le plus grand réservoir de carbone renouvelable sur Terre, sa valorisation reste encore limitée par sa récalcitrance à la dégradation. Bien que sa bioconversion ait été largement étudiée dans le cadre de la production de bio-combustibles, d’autres approches comme la plateforme des carboxylates permettent de produire des intermédiaires et composés chimiques d’intérêt industriel. De plus dans la Nature, la lignocellulose est prise en charge par des écosystèmes microbiens qui déploient une large diversité enzymatique. Ainsi, nous avons étudié l’enrichissement de communautés microbiennes naturelles issues d’écosystèmes digestifs animaux sur paille de blé et en conditions d’anaérobiose en bioréacteur contrôlé, en vue de produire des carboxylates. Via une procédure de culture en bioréacteur batch séquentiel, deux communautés stables ont été obtenues à partir de rumen bovin (nommée RWS) et de microbiote intestinal de termite de l’espèce Nasutitermes ephratae (nommée TWS). RWS et TWS dégradaient 55% et 45% du substrat non prétraité, en produisant 6,5 g-AGV.L-1 et 5,8 g-AGV.L-1 en 15 jours, respectivement. En combinant des approches de suivi dynamique des paramètres macroscopiques, des activités enzymatiques impliquées dans la dégradation du substrat, ainsi que par une étude métaprotéomique dynamique, nous avons pu révéler des particularités intéressantes entre ces deux communautés microbiennes. De plus, la communauté RWS a été soumise à des prétraitements du substrat permettant d’augmenter sa vitesse de production de carboxylates
Lignocellulose (LC) is the most abundant terrestrial reservoir of renewable carbon on Earth but its valorization is still limited due to its recalcitrance. In the field of bioconversion, the production of biofuels has been widely studied, whereas others valorization routes – as the carboxylate platform- enable the production of intermediate building blocks or industrial componuds. However in Nature, the recycling of LC is performed by microbial consortia which deploy complex arsenals of enzymes to deconstruct LC. In this PhD thesis we studied the anaerobic enrichment of natural microbial communities from animal digestive systems, aiming to production of carboxylates from wheat straw as substrate. Thanks to a sequencial batch reactor procedure, we obtained two stable communities from bovine rumen (named RWS) and intestinal microbiote from the termite species Nasutitermes ephratae (named TWS). RWS and TWS transformed 55% and 45% VS unpretreated wheat straw into 230 mCmol-AGV.L-1 (6.5 g-AGV.L-1) and 180 mCmol-AGV.L-1 (5.8 g-AGV.L-1) within 15 days, respectively. Combing the dynamic measurment of macroscopic parameters (i.e. degradation and production) to the quantification of enzymatic activities involved in LC degradation, as well as to a dynamic metaproteomic approach we revealed some interesting features between these two consortia. Moreover, RWS was used to study the impact of pretreatments on its acidogenic biological potential

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Razal, Ramon A. "Studies on lignin biosynthesis and biodegradation." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07282008-135150/.

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19

Fatokun, Evelyn. "Exploration of Nahoon beach milieu for lignocellulose degrading bacteria and optimizing fermentation conditions for holocellulase production by selected strains." Thesis, University of Fort Hare, 2016. http://hdl.handle.net/10353/1529.

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A significant trend in the modern day industrial biotechnology is the utilization and application of renewable resources, and ecofriendly approach to industrial processes and waste management. As a consequence thereof, the biotechnology of holocellulases: cellulase and xylanase and, enzymatic hydrolysis of renewable and abundant lignocellulosic biomass to energy and value added products are rapidly increasing; hence, cost effective enzyme system is imperative. In that context, exploration of microbiota for strains and enzymes with novel industrial properties is vital for efficient and commercially viable enzyme biotechnology. Consequent on the complex characteristics of high salinity, variable pressure, temperature and nutritional conditions, bacterial strains from the marine environment are equipped with enzyme machinery of industrial importance for adaptation and survival. In this study, bacterial strains were isolated form Nahoon beach and optimized for holocellulase production. Three isolates selected for lignocellulolytic potential were identified by 16S ribosomal deoxyribonucleic acid (rDNA) sequence analysis. Isolate FS1k had 98 percent similarity with Streptomyces albidoflavus strain AIH12, was designated as Streptomyces albidoflavus strain SAMRC-UFH5 and deposited in the GenBank with accession number KU171373. Similarly, isolates CS14b and CS22d with respective percentage similarity of 98 and 99 (percent) with Bacillus cereus strains and Streptomyces sp. strain WMMB251 were named Bacillus cereus strain SAMRC-UFH9 and Streptomyces sp. strain SAMRC-UFH6; and were deposited in the GenBank with accession number KX524510 and KU171374 respectively. Optimal pH, temperature and agitation speed for cellulase production by S. albidoflavus strain SAMRC-UFH5, and B. cereus strain SAMRC-UFH9 were 6 and 7; 40 and 30 (°C); and 100 and 150 (rpm) respectively; while xylanase production was optimal at pH, temperature and agitation speed of 8 and 7; 40 and 30 (°C); and 150 and 50 (rpm) respectively. Maximum cellulase activity of 0.26 and 0.061(U/mL) by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 were attained at 60 h respectively, while maximal xylanase activity of 18.54 and 16.6 (U/mL) was produced by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 at 48 h and 60 h respectively. Furthermore, xylanase production by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 was maximally induced by wheat straw and xylan respectively, while cellulase production was best induced by mannose and carboxymethyl cellulose respectively. On the other hand, cellulase and xylanase production by Streptomyces sp. strain SAMRC-UFH6 was optimal at pH, temperature and agitation speed of 7 and 8, 40 °C and 100 rpm, respectively. Highest production of cellulase and xylanase was attained at 84 and 60 h with respective activity of 0.065 and 6.34 (U/mL). In addition, cellulase and xylanase production by the strain was best induced by beechwood xylan. Moreover, xylanase produced by Streptomyces sp. strain SAMRC-UFH6 at optimal conditions was characterized by optimal pH and temperature of 8 and 80-90 °C respectively; retaining over 70 percent activity at pH 5-10 after 1 h and 60 percent of initial activity at 90 °C after 90 min of incubation. In all, optimization improved cellulase and xylanase production yields, being 40 and 95.5, 10.89 and 72.17, and 10 and 115- fold increase by S. albidoflavus strain SAMRC-UFH5, B. cereus strain SAMRC-UFH9 and Streptomyces sp. SAMRC-UFH6 respectively. The results of this study suggest that the marine bacterial strains are resource for holocellulase with industrial applications.

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Tu, Maobing. "Enzymatic hydrolysis of lignocellulose : cellulase enzyme adsorption and recycle." Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/31175.

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Producing ethanol from the bioconversion of lignocellulosic substrates is one of the most promising technologies to decrease fossil fuel utilization. However, the current economics of the bioconversion process prohibit its commercialization due to the high cost of cellulase enzymes. One potential means to decrease enzyme costs is to recycle enzymes during the bioconversion process. The initial work focused on comparing the distribution of cellulases among the solid and liquid phases after a typical enzymatic hydrolysis of Avicel and an organosolv pretreated Douglas fir substrate. It was shown that 50% of the applied cellulases desorbed into the liquid phase after the hydrolysis of an ethanol pretreated D. fir substrate compared to 76% in the case of Avicel. By exploiting the natural affinity of cellulases for cellulosic substrates, the free enzymes were recovered via readsorption onto fresh substrates. Using this approach, 85% of the free enzymes could be recovered, compared to an 82% recovery predicted by the Langmuir isotherm model. A novel recycling strategy for recovering both the free and bound enzymes was developed where Tween 80 was added at the beginning of the hydrolysis, followed by the addition of fresh substrate to recover free enzymes after hydrolysis. The cellulases from T. reesei ( Hypocrea jecorina ) could be recycled for four consecutive rounds of hydrolysis of an ethanol pretreated (EPLP) substrate with the addition of 0.2% Tween 80, compared to one round with a steam exploded (SELP) substrate, presumably due to the higher lignin content of the SELP substrate. Comparing isolated lignin preparations from SELP and EPLP, it was shown that CEL-SELP lignin exhibited a greater capacity to bind cellulases than CEL-EPLP lignin. A reduction in the adsorption of cellulases to lignin was achieved by the addition of Tween 80. The recycling of β-glucosidase was achieved by immobilization on an inert carrier, Eupergit C. The immobilized β-glucosidase exhibited improved operational stability and an increase in the apparent K[sub m] and V[sub max]. Overall, the results demonstrated that enzyme recycling using a combination of surfactants, readsorption onto substrates and enzyme immobilization could potentially decrease enzyme costs in the hydrolysis of softwoods during the bioconversion process.
Forestry, Faculty of
Graduate

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Fraser, M. A. "Lignocellulose degradation by Coriolus versicolor : Ultrastructural and biochemical studies." Thesis, University of Greenwich, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384559.

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22

Qi, Bing Cui. "The bio-disposal of lignocellulose substances with activated sludge." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52489.

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Thesis (PhD)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: Lignocellulose is the principal form of biomass in the biosphere and therefore the predominant renewable source in the environment. However, owing to the chemical and structural complexity of lignocellulose substrates, the effective and sustainable utilization of lignocellulose wastes is limited. Many environments where lignocellulose residues are ordinarily stored can be highly acidic (e.g. landfills), and under these circumstances biodegradation of the lignocellulose is slow and unhygienic. Owing to the metabolic activities of the micro-organisms, the initially acidified habitats rapidly undergoes self-neutralization. A number of pathogenic bacteria (coliforms and Salmonella sp.) are present during this slow degradation process and it is therefore imperative to improve the efficiency and hygienic effects of the biodegradation of the lignocellulose. Although the fundamentals of biodegradation of lignocellulose have been widely investigated, many issues still need to be resolved in order to develop commercially viable technology for the exploitation of these waste products. For example, owing to the complex, heterogeneous structure of lignocellulose, the degree of solubilization, modification and conversion of the different components are not clear. Likewise, the overall anaerobic degradation of lignocellulose is not understood well as yet. In this study, the emphasis was on the promotion of solid anaerobic digestion of lignocellulose wastes for environmental beneficiation and waste reutilization. The degradation of lignocellulose in landfill environments was first simulated experimentally. Once the microbial populations and the degradation products of the system were characterized, the promotion of anaerobic digestion by use of activated sludge was studied. This included acidogenic fermentation, as well as recovery of the methanogenic phase. Moreover, special attention was given to the further disposal of humic acids or humic acid bearing leachates formed in the digestive system, since these acids pose a major problem in the digestion of the lingocellulose. With ultrasonication, approximately 50% of the lower molecular weight fraction of humic acids could be decomposed into volatile forms, but the higher molecular weight fraction tended to aggregate into a colloidal form, which could only be removed from the system by making use of ultrasonically assisted adsorption on preformed aluminium hydroxide floes. This was followed by an investigation of the microbial degradation of humic acids and the toxicity of these acids to anaerobic consortia. Further experimental work was conducted to optimize the biological and abiological treatment of lignocellulose in an upflow anaerobic sludge blanket (DASB) reactor fed with glucose substrate. The humic acids could be partially hydrolysed and decomposed by the acid fermentative consortia of the granules in the DASB reactor. Finally, solid mesothermophilic lignocellulose anaerobic digestive sludge can be viewed as a humus-rich hygienic product that can improve the fertility and water-holding capacity of agricultural soil, nourish plants and immobilize heavy metals in the environment as a bioabsorbent.
AFRIKAANSE OPSOMMING: Lignosellulose is die hoofbron van biomassa in die biosfeer en is daarom ook die belangrikste hernubare bron in die omgewing. As gevolg van die chemiese en strukturele kompleksiteit van lignosellulose substrate, is die doeltreffende en volhoubare benutting van lignosellulose afval egter beperk. Die suurgehalte van die omgewings waar lignosellulose reste gewoonlik gestoor word, soos opvullingsterreine, kan hoog wees en onder hierdie omstandighede is die biodegradasie van die lignosellulose stadig en onhigiënies. As gevolg van die metaboliese aktiwiteite van die mikro-organismes ondergaan die aanvanklik aangesuurde habitatte vinnig self-neutralisasie. 'n Aantal patogeniese bakterieë (koliforme en Salmonella sp.) is deurgaans gedurende dié stadige natuurlike proses teenwoordig en dit is dus van die grootste belang om die effektiwiteit en die higiëne van die bioafbreking van die lignosellulose-substraat te verhoog. Alhoewel die grondbeginsels van die bioafbreking van lignosellulose reeds wyd ondersoek is, moet verskeie probleme nog opgelos word ten einde kommersieel haalbare tegnologie te ontwikkel vir die ontginning van afvalprodukte. Byvoorbeeld, as gevolg van die komplekse, heterogene struktuur van lignosellulose, is die graad van solubilisering en die modifikasie en omskakeling van verskillende komponente nog onduidelik. Net so word die algehele anaerobiese afbreking van lignosellulose ook nog nie ten volle verstaan nie. In hierdie ondersoek het die klem geval op die bevordering van soliede anaerobiese digestie van lignosellulose afval vir omgewingsverbetering en die benutting van die afval. Die afbreking van lignosellulose in opvullingsterreine is eers eksperimenteel gesimuleer. Nadat die mikrobiese populasies en die afbrekingsprodukte gekarakteriseer is, is die bevordering van anaerobiese digestie deur die gebruik van geaktiveerde slyk bestudeer. Dit het asidogeniese fermentasie ingesluit, sowel as herwinning van die metanogeniese fase. Spesiale aandag is gegee aan die verdere verwerking van humus sure en humussuurbevattende legate wat in die digestiewe stelsel gegenereer is, aangesien die sure probleme veroorsaak het met die vertering van die lignosellulose. Met ultrasoniese straling is nagenoeg 50% van die lae-molekulêre massafraksie van die humussure ontbind in vlugtige vorm, maar die hoë-molekulêre massafraksie het geneig om in 'n kolloïdale vorm te aggregeer, wat slegs uit die stelsel verwyder kon word deur middel van ultrasonies ondersteunde adsorpsie op voorafgevormde aluminiumhidroksiedvlokkies. Dit is gevolg deur 'n ondersoek na die mikrobiese afbreking van humus sure en die toksisiteit van die sure ten opsigte van anaerobiese konsortia. Verdere eksperimentele werk is gedoen ten opsigte van die biologiese en abiologiese behandeling van lignosellulose in 'n opwaartsvloeiende anaerobiese slikkombersreaktor (OASK) gevoer met glukosesubstrate. Die humus sure kon gedeeltelik gehidroliseer en ontbind word deur die suurgistende konsortia van die granules in die OASK reactor. Ten slotte kan die vaste termofiliese-mesofiliese anaerobiese lignosellulose verteringslik ook gesien word as 'n humusryke higiëniese produk wat die vrugbaarheid en die waterhoudende vermoë van landbougrond kan verhoog, plante kan voed en kan funksioneer as bioabsorbeerder van swaarmetale in die omgewing.

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23

Alriksson, Björn. "Ethanol from lignocellulose : management of by-products of hydrolysis /." Karlstad : Faculty of Technology and Science, Chemistry, Karlstads universitet, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-3314.

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24

David, Grégoire. "Eco-conversion de résidus lignocellulosiques de l'agriculture en matériaux composites durables à matrice biopolyester." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTG030.

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Cette thèse consiste à développer et étudier de nouveaux matériaux composites biosourcés et biodégradables à partir de constituants dérivés des déchets de l'agriculture dans le cadre du projet européen NoAW (https://noaw2020.eu). Tous les composants sont dérivés de sous-produits agricoles : des polyhydroxyalcanoates (PHA, biopolyester bactérien et biodégradable en conditions naturelles) produits par digestion anaérobie d’effluents agricoles sont utilisés comme matrices et des fibres de sarments de vigne comme charges de renfort. Les composites sont préparés par extrusion. L'objectif de cette thèse est d'apporter de nouvelles connaissances sur les relations entre le procédé de mise en œuvre des biocomposites, leur structure et leurs propriétés fonctionnelles. Les biocomposites sont développés en considérant une balance performance-coût environnemental. Pour cela, la thèse se focalise sur 2 questions scientifiques majeures : (i) étude de l’impact de l’interface charge/matrice sur les propriétés fonctionnelles des matériaux biocomposites via pré-traitements de surface des particules lignocellulosiques ; (ii) étude de la durabilité de tels matériaux par évaluation dès la conception des impacts environnementaux. Ainsi, une attention particulière est accordée à l’interface charge/matrice, identifiée comme un facteur clé influençant les propriétés finales du composite. Un prétraitement de surface des fibres sans solvant (chromatogénie) est adapté afin de moduler l’interface charge/matrice. Cette nouvelle méthode d’estérification en voie gazeuse est tout d’abord étudiée sur des particules micrométriques de cellulose. Une fois la preuve de concept établie, elle est appliquée aux fibres lignocellulosiques, plus complexes. Les sarments de vigne, déchets agricole abondant en région Occitanie, sont étudiés comme ressource potentielle pour la production de charges de renfort. Une fois collectés et séchés, ils sont broyés en voie sèche afin d’obtenir des particules micrométriques. La variabilité de la matière première étant un des verrous concernant l’utilisation de la biomasse par les industriels, différents cépages sur plusieurs années ont été étudiés. Dans une logique de bioraffinerie, l’extraction préalable de molécules d’intérêt tels que les polyphénols est envisagée avant d’utiliser le résidu, à savoir les sarments épuisés, comme charge de renfort. L’impact environnemental des matériaux développés est évalué afin de guider les choix stratégiques et obtenir le matériau alliant à la fois performance et faible empreinte écologique. Une analyse de cycle de vie dans le cadre d’une application de barquette rigide alimentaire est réalisée en réunissant des données des acteurs de la filière. De plus, une étude de la biodégradabilité des matériaux finaux est menée. Cette thèse englobe plusieurs composantes pluridisciplinaires afin d’avoir une vision d’ensemble et décloisonnée des matériaux composites mis au point
This thesis aims at developing new fully biosourced and biodegradable composite materials from agricultural residues in the frame of the European project NoAW (https://noaw2020.eu). All the components are derived from agro-wastes: polyhydroxyalkanoates (PHA, bacterial biopolyester and biodegradable in natural conditions) produced by anaerobic digestion of agricultural effluents are used as matrix and vine shoot fibers as fillers. Biocomposites are prepared by melt extrusion. The objective of this thesis is to bring new knowledge on the relationships between the processes used to produce the fillers and the biocomposites, the resulting structure of biocomposites and their functional properties. Biocomposites are developed considering a balance between performance and environmental cost. For this purpose, the thesis focuses on 2 major scientific questions: (i) study of the impact of the filler/matrix interface on the functional properties of biocomposite materials via surface pre-treatments of lignocellulosic particles; (ii) study of the durability of such materials by assessment from the design of the environmental impacts. Thus, special attention is given to the filler/matrix interface, identified as a key factor for the final properties of the composite. A solvent-free surface pretreatment of fibers (chromatogeny) is adapted to modulate the filler/matrix interface. This new method of gas-phase esterification is first studied on micrometric particles of cellulose. Once the proof of concept is established, it is applied to lignocellulosic fibers that are more complex. The vine shoots, agricultural waste abundant in Occitania region, are studied as a potential resource for the production of fillers for composites. Once collected and dried, they are milled using dry fractionation to obtain micrometric sized particles. The variability of the raw material being one of the bottlenecks concerning the use of lignocellusoic biomass by manufacturers, different grape species over several years are studied. In a biorefinery approach, the extraction of molecules of interest, e.g. polyphenols, is considered before using the residue, namely exhausted shoots, as a reinforcing fillers. The environmental impact of the produced biocomposites is evaluated to guide strategic choices and obtain materials displaying a good balance between performance and environmental footprint. A life cycle assessment in the context of a food rigid tray application is carried out, collecting data from sector’s players. In addition, a study of the biodegradability of the final materials is conducted. This thesis encompasses multidisciplinary fields in order to have a decompartmentalized overview of the developed composite materials

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Leonhardt, Sabrina, Enrico Büttner, Anna Maria Gebauer, Martin Hofrichter, and Harald Kellner. "Draft Genome Sequence of the Sordariomycete Lecythophora (Coniochaeta) hoffmannii CBS 245.38." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-235647.

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Lecythophora (Coniochaeta) hoffmannii, a soil- and lignocellulose-inhabiting sordariomycete (Ascomycota) that can also live as a facultative tree pathogen causing soft rot, belongs to the family Coniochaetaceae. The strain CBS 245.38 sequenced here was assembled into 869 contigs, has a size of 30.8 Mb, and comprises 10,596 predicted protein-coding genes.

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Karlsson, Anders. "Adhesion av mikroorganismer till lignocellulosa." Thesis, Mälardalen University, Mälardalen University, Department of Biology and Chemical Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-1339.

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The aim of the project was to develop a method to investigate differences in adhesion of microorganisms to materials that contains lignocellulose. The method was tested on a gram-positive (Micrococcus lutea) and one gram-negative (E-coliJM109) bacteria.

The study was begun by cultivation of the two microorganisms. The cultivation was done to calculate the generation times of the bacteria and to obtain growth curves. Cells from these cultivations were also frozen (-70ºC) and later used for inoculation.

At STFI-Packforsk AB the total charge on the mass was measured and later a conductivity titration on the mass was executed as well, all to find out more about the different properties of the mass. Properties that in a later part of this study could possibly be linked to the adhesion of cells to the pulp. The adhesion experiments that were executed gave poor results. The adhesion experiment with M. lutea was the only experiment that gave a reproducible result. In this experiment M. lutea was contacted with bleached leaf. A reduction of cells was observed in all of the dilutions where M. lutea had been in contact with the mass. The number of colony forming units of the culture was 1,2×10⁷ before the adhesion and 2×10⁶ subsequently.

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Auer, Lucas. "Vers la maîtrise des communautés microbiennes lignocellulolytiques : impact de la source d'inoculum et du prétraitement du substrat sur le fonctionnement des communautés." Thesis, Toulouse, INSA, 2016. http://www.theses.fr/2016ISAT0050/document.

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La lignocellulose est le composant principal des parois végétales et donc le biopolymère végétal le plus abondant sur Terre. Sa transformation en molécules d’intérêt industriel est donc une voie prometteuse pour diminuer la consommation de ressources fossiles. Au sein de la plateforme des carboxylates, la transformation de la lignocellulose repose sur l’utilisation de communautés bactériennes. Mais s’ils sont augmentés par des approches de prétraitement du substrat, les rendements sont encore faibles. Afin de les améliorer, nous avons ici testé les capacités de dégradations de communautés microbiennes issues de l’enrichissement de rumen bovin et d’intestin de termites. Afin de caractériser l’effet de la source d’inoculum et du prétraitement du substrat sur le fonctionnement des communautés sélectionnées, une approche de séquençage 16S a été utilisée. Celle-ci a permis la comparaison des compositions de communautés obtenues, mais également de leurs dynamiques au cours de la transformation du substrat lignocellulosique. Les conditions de culture imposées semblent avoir un effet très fort sur la composition des communautés sélectionnées puisque malgré leurs différences, celles-ci présentent d’importantes similitudes et sont bien plus proches que ne l’étaient les inocula initiaux. Enfin, les communautés associées à la dégradation du substrat lignocellulosique montrent des dynamiques très marquées, caractérisées par une importante baisse de diversité et la dominance de quelques populations bactériennes seulement lors du maximum de dégradation
Lignocellulose is the main component of vegetal cell wall and is thus the most abundant biopolymer on Earth. Its conversion into industrially relevant molecules is of concern to reduce fossil resources consumption. In the dedicated carboxylates platform, lignocellulose conversion relies on the metabolic potential of microbial consortia, but lignocellulose transformation rates can still be improved, despite substrate pretreatment approaches. In order to improve these rates, we here tested the transformation capacities of microbial communities originated from cow rumen and termite guts. 16S sequencing was used to characterize the effects of inoculum source and substrate pretreatment on the selected communities’ functioning. It allowed the comparison between obtained communities, but also between their dynamics during lignocellulose transformation. Culture conditions appeared to have a strong effect on the selected communities, which presented high similarities despite differences between initial inocula. Finally, communities associated to lignocellulose degradation showed marked dynamics, with a strong decrease in diversity indexes and the dominance of a few bacterial populations during the degradation maximum

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Ciampoli, Daria. "Lignocellulose-degrading enzymes from the gut of okapi and elephant." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.

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The present thesis dealt with microbial communities derived from the gut of large herbivores which efficiently degrade lignocellulose. There are essentially no protocols for the cultivation of these microbiomes, which may differ from animal to animal. Here, a first protocol was assessed on the basis of the one for giant pandas, and applied to okapi and elephant. Faecal samples were collected at the Copenhagen zoo to prepare an inoculum (the gut microbiota) fed with either cellulose, hemicellulose, lignin or animal feed. Pure substrates were used to select different microbial sub-groups, while the animal feed was used as a positive control. Fermentation kinetics were followed in terms of biogas production volume and composition, volatile fatty acids production, cell counting and pH. Some adjustments to the protocol were made for the second experiment (on okapi alone, a foregut fermenter), concerning the substrate to inoculum ratio, and improving the gut microbiome cleaning procedure. Both modifications aimed at designing a bioreactor system less intensive than the first experiment one. Following the observation of a stable foam while preparing gut microbiomes, biosurfactants and bioemulsifiers were tested. In the third experiment, the improved protocol was tested on the elephant, as a representative of a hindgut fermenter. At the end of laboratory cultivation, an attempt to identify and characterize the enzymatic fractions in bioreactors was made through an initial colorimetric and chromatographic investigation, followed by anion exchange column fractionation and SDS-Page analysis. The preliminary results highlighted that the two fermentations are clearly distinct from one another, and point to a markedly higher degradation capacity of okapi gut microbiomes. Both microbiomes were more active on hemicellulose. However, elephant gut microbiomes could produce almost uniquely acetic acid with hemicellulose substrate, an interesting observation for future applications.

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Salvatore, Ludovica. "Lignocellulose-degrading enzymes from the gut of giraffe and zebra." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.

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In the present thesis the gut microbiome of large herbivores was targeted to identify the presence of active lignocellulose-degrading enzymes. As there are essentially no protocols for the cultivation of these microbiomes, which may differ from animal to animal, this study aimed at developing a reliable protocol for their cultivation, using the giraffe and zebra as target animals in order to compare a foregut and hindgut fermenter. Gut microbiome inocula were incubated with pure substrates (either cellulose, hemicellulose or lignin) or animal feed. Fermentation kinetics in terms of biogas and volatile fatty acids (VFAs) production, cell count, pH analysis and production of biosurfactants and bio-emulsifiers were performed. Giraffe gut microbiomes were more active on hemicellulose than on other portions of lignocellulose. This may be due to the fact that the retention time of the ingesta is just 40 hours. This may suffice to access and break down hemicellulose, that is, the external matrix in the complex lignocellulose structure. As for the zebra, the gut microbiome was particularly active on the feed to which it was adapted rather than the pure substrates. In the second part of the experiments, the characterization of the enzymatic activity of the samples obtained at the end of the fermentation was performed to detect the presence of enzymes in the gut of the two animals through an initial calorimetric and chromatographic investigation by HPLC, followed by anion exchange column fractionation and SDS-Page analysis. The results obtained from the enzymatic characterization do not clearly identify an enzymatic activity in the gut microbiome of both animals. Changes to the original protocol are needed, such as, for example, a change in the enzyme concentration to be analyzed and the sampling times.

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30

Alriksson, Björn. "Ethanol from lignocellulose : Alkali detoxification of dilute-acid spruce hydrolysates." Licentiate thesis, Karlstad University, Faculty of Technology and Science, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-2632.

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Detoxification of dilute-acid lignocellulose hydrolysates by treatment with Ca(OH)₂(overliming) efficiently improves the production of fuel ethanol, but is associated with drawbacks like sugar degradation and CaSO₄ precipitation. In factorial designed experiments, in which pH and temperature were varied, dilute-acid spruce hydrolysates were treated with Ca(OH)₂, NH₄OH or NaOH. The concentrations of sugars and inhibitory compounds were measured before and after the treatments. The fermentability was examined using the yeast Saccharomyces cerevisiae and compared with reference fermentations of synthetic medium without inhibitors. The treatment conditions were evaluated by comparing the balanced ethanol yield, which takes both the degradation of sugars and the ethanol production into account. Treatment conditions resulting in excellent fermentability and minimal sugar degradation were possible to find regardless of whether Ca(OH)₂, NH₄OH or NaOH was used. Balanced ethanol yields higher than those of the reference fermentations were achieved for hydrolysates treated with all three types of alkali. As expected, treatment with Ca(OH)₂ gave rise to precipitated CaSO₄. The NH₄OH treatments gave rise to a brownish precipitate but the amounts of precipitate formed were relatively small. No precipitate was observed in treatments with NaOH. The possibility that the ammonium ions from the NH₄OH treatments gave a positive effect as an extra source of nitrogen during the fermentations was excluded after experiments in which NH₄Cl was added to the medium. The findings presented can be used to improve the effectiveness of alkali detoxification of lignocellulose hydrolysates and to minimize problems with sugar degradation and formation of precipitates.

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31

Barbier, Jérémie. "Relation structure/réactivité en conversion hydrothermale des macromolécules de lignocellulose." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2010. http://tel.archives-ouvertes.fr/tel-00562111.

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Ce travail porte sur l'étude des voies réactionnelles accompagnant la liquéfaction desconstituants de la biomasse lignocellulosique dans un milieu aqueux proche du pointcritique. La stratégie expérimentale consiste à étudier la réaction en unité pilote decomposés lignocellulosiques modèles et à développer une approche analytiquemultitechnique originale afin de caractériser les structures et les masses moléculairesdes produits. Les résultats obtenus montrent que les schémas réactionnels sontcomplexes faisant intervenir de nombreuses voies de fragmentation et de condensationcompétitives. L'étude cinétique à différents temps de séjour montre que la fractionglucidique de la biomasse lignocellulosique a une réactivité très différente de sa fractionligneuse.

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32

Barbier, Jérémie Alain. "Relation structure/réactivité en conversion hydrothermale des macromolécules de lignocellulose." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14144/document.

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Ce travail porte sur l'étude des voies réactionnelles accompagnant la liquéfaction desconstituants de la biomasse lignocellulosique dans un milieu aqueux proche du pointcritique. La stratégie expérimentale consiste à étudier la réaction en unité pilote decomposés lignocellulosiques modèles et à développer une approche analytiquemultitechnique originale afin de caractériser les structures et les masses moléculairesdes produits. Les résultats obtenus montrent que les schémas réactionnels sontcomplexes faisant intervenir de nombreuses voies de fragmentation et de condensationcompétitives. L'étude cinétique à différents temps de séjour montre que la fractionglucidique de la biomasse lignocellulosique a une réactivité très différente de sa fractionligneuse
This work deals with the study of the reaction pathway during the lignocellulosicconstituent liquefaction by water near its critical point. Experimental method consists ininvestigation of lignocellulosic model compounds conversion in pilot plant combined withdevelopment of a new multitechnique analytical approach in order to characterizeproduct chemical structures and molecular weights. Results show that reaction pathwaysare very complex consisting to several fragmentation and condensation competitivereactions. The kinetic study with different reaction times reveals an important differenceof comportment for the glucidic fraction than the lignin fraction of biomass

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33

Kvillborn, Carin. "Enzymatic Pretreatment of Lignocellulose Rich Waste for Improved Biogas Production." Thesis, Linköpings universitet, Tema vatten i natur och samhälle, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-104974.

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The present study aimed to investigate the methane yield from anaerobic digestion of a lignocellulosic substrate subjected to different pretreatments. The lignocellulosic forest residues materials were milled and then pretreated with the organic solvent NMMO (N-Methylmorpholine N-oxide) and/or the lignolytic enzymes laccase and versatile peroxidase at a dosage of 60 U g-1 total solids (TS) substrate. The amount of methane produced was studied in a biomethane potential assay with inocula from a thermophilic biogas reactor treating municipal waste. All samples were run in triplicates. Due to the large amount of samples, two biomethane potential assays were conducted: series 10 & 20 and series 30 & 40. The gas production results show that NMMO-treated forest residues yielded 130 NmL CH4 g-1 volatile solids (VS) substrate and the untreated forest residues yielded 95 NmL CH4 g-1 VS substrate for series 10 & 20. For series 30 & 40, both untreated and NMMO-treated forest residues yielded 140 NmL CH4 g-1 VS substrate. NMMO-treatment appears to be favourable and no advantages from the enzyme pretreatment could be seen in terms of gas yield. An analysis of the reaction fluid after the enzymatic treatment showed presence of phenols, an indication of successful lignin hydrolysis.
Studien avsåg att undersöka metanutbytet från anaerob nedbrytning med förbehandlad lignocellulosa som substrat. Lignocellulosamaterialet, i form av skogsavfall, maldes och förbehandlades därefter med det organiska lösningsmedlet NMMO (N-metylmorfolin-N-oxid) och/eller de lignolytiska enzymerna laccase och versatile peroxidas med dosen 60 U g-1 torrsubstanshalt (TS). Mängden producerad metan undersöktes i en biometanpotentialanalys med inocula från en termofil biogasreaktor, som behandlade hushållsavfall. Triplikat av varje prov användes för att öka den statistiska stabiliteten. På grund av det stora antalet prover genomfördes studien i två omgångar: Serie 10 & 20 samt serie 30 & 40. Resultaten visade att det NMMO-behandlade skogsavfallet gav 130 NmL CH4 g-1 organisk substans (VS) och det obehandlade skogsavfallet gav 95 NmL CH4 g-1 VS i serie 10 & 20. Både obehandlat och NMMO- behandlat skogsavfall gav 140 NmL CH4 g-1 VS i serie 30 & 40. Förbehandling med NMMO verkar vara fördelaktig medan enzymbehandling endast resulterade i en smärre ökning av gasproduktionen. En analys av vätskan efter enzymbehandlingen visade förekomst av fenoler, vilket visar på en lyckad ligninnedbrytning.

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Orejuela, Lourdes Magdalena. "Lignocellulose deconstruction using glyceline and a chelator-mediated Fenton system." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/81255.

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Non-edible plant biomass (lignocellulose) is a valuable precursor for liquid biofuels, through the processes of pretreatment and saccharification followed by fermentation into products such as ethanol or butanol. However, it is difficult to gain access to the fermentable sugars in lignocellulose, and this problem is principally associated with limited enzyme accessibility. Hence, biomass pretreatments that destroy native cell wall structure and allows enzyme access are required for effective biomass conversion techniques. This research studied two novel pretreatment methods on two wood species: 1) a deep eutectic solvent (DES) that, under heat, swells lignocellulose and partially solubilizes cell wall materials by causing breakage of lignin-carbohydrate linkages and depolymerization of the biomass components, and 2) a chelator-mediated Fenton reaction (CMF) that chemically modifies the nanostructure of the cell wall through a non-enzymatic cell wall deconstruction. After pretreatment, utilizing analytical techniques such as nuclear magnetic spectroscopy, wide angle x-ray scattering, and gel permeation chromatography, samples were analyzed for chemical and structural changes in the solubilized and residual materials. After single stage DES (choline-chloride-glycerol) and two stage, CMF followed by DES pretreatments, lignin/carbohydrate fractions were recovered, leaving a cellulose-rich fraction with reduced lignin and hemicellulose content as determined by compositional analysis. Lignin and heteropolysaccharide removal by DES was quantified and the aromatic-rich solubilized biopolymer fragments were analyzed as water insoluble high molecular weight fractions and water-ethanol soluble low molecular weight compounds. After pretreatment for the hardwood sample, enzyme digestibility reached a saccharification yield of 78% (a 13-fold increase) for the two stage (DES/CMF) pretreated biomass even with the presence of some lignin and xylan remained on the pretreated fiber; only a 9-fold increase was observed after the other sequence of CMF followed by DES treatment. Single stage CMF treatment or single stage DES pretreatment improved 5-fold glucose yield compared to the untreated sample for the hardwood sample. The enhancement of enzymatic saccharification for softwood was less than that of hardwoods with only 4-fold increase for the sequence CMF followed by DES treatment. The other sequence of treatments reached up to 2.5-fold improvement. A similar result was determined for the single stage CMF treatment while the single stage DES treatment reached only 1.4-fold increase compared to the untreated softwood. Hence, all these pretreatments presented different degrees of biopolymer removal from the cell wall and subsequent digestibility levels; synergistic effects were observed for hardwood particularly in the sequence DES followed by CMF treatment while softwoods remained relatively recalcitrant. Overall, these studies revealed insight into two novel methods to enhance lignocellulosic digestibility of biomass adding to the methodology to deconstruct cell walls for fermentable sugars.
Ph. D.
Wood is a valuable material that can be used to produce liquid biofuels. Wood main components are biopolymers cellulose, hemicellulose and lignin that form a complex structure. Nature has locked up cellulose in a protective assembly that needs to be destroyed to gain access to cellulose, convert it to glucose and then ferment it to bioalcohol. This process is principally associated with limited enzyme accessibility. Therefore, biomass pretreatments that deconstruct native cell wall structure and allow enzyme access are required for effective biomass conversion techniques. This research studied two novel pretreatment methods on two wood species: 1) a deep eutectic solvent called glyceline that, under heat, swells wood and partially solubilizes cell wall materials by causing breakage of bonds and converting it into smaller molecules (monomers and oligomers), and 2) a chelator-mediated Fenton system (CMF) that chemically modifies the structure of the cell wall. Pretreatments were tested individually and in sequence in sweetgum and southern yellow pine. After pretreatments, utilizing analytical techniques, fractions were investigated for chemical and structural changes in the solubilized and residual materials. Treated wood samples were exposed to enzymatic conversion. A maximum 78% of glucose yield was obtained for the glyceline followed by CMF pretreated wood. For yellow pine only a 24% of glucose yield was obtained for the CMF followed by glyceline treatment. All these pretreatments presented different degrees of biopolymer removal from the cell wall and subsequent enzyme conversion levels. Overall, these studies revealed insight into two novel methods to enhance wood conversion adding to the methodology to deconstruct cell walls for fermentable sugars.

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Roman, Henry James. "The degradation of lignocellulose in a biologically-generated sulphidic environment." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1004057.

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South Africa is renowned for its mining industry. The period over which the polluted waters from the existing and abandoned mines will require treatment has driven research into the development of passive treatment systems. These waters are characterised by a low pH, high concentrations of heavy metals, high levels of sulphate salts and low concentrations of organic material. The biological treatment of these waters has been a subject of increasing focus as an alternative to physicochemical treatment. The utilisation of lignocellulose as a carbon source has been restricted by the amount of reducing equivalents available within the lignocellulose matrix. After a few months of near 100% sulphate reduction, it was found that although there was a large fraction of lignin and cellulose remaining, sulphate reduction was reduced to less than 20%. The present study demonstrated that lignocellulose can be utilised as a carbon source for sulphate reduction. It was established that lignocellulose degradation was enhanced under biosulphidogenic conditions and that lignin could be degraded by a sulphate reducing microbial consortium. It was established using lignin model compounds synthesized in our laboratory, that the bonds within the lignin polymer can be cleaved within the sulphidic environment. The presence of cellulolytic enzymes, using CMCase as a marker enzyme, was detected within the sulphate reducing microbial consortium. Based on the results obtained a descriptive model was formulated for the degradation of lignocellulose under biosulphidogenic conditions. It was determined that the initial reduction in sulphate observed using lignocellulose as a carbon source was due to the easily extractable components. The degradation of which resulted in the production of sulphide, which aided in the degradation of lignin, allowing greater access to cellulose. Once the easily extractable material is exhausted, the cycle is halted, unless the sulphide production can be maintained. This is the focus of an ongoing project, testing the hypothesis that an easy to assimilate carbon source added after exhaustion of the easily extractable material, can maintain the sulphide production.

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Bach, Kristensen Jan. "Enzymatic hydrolysis of lignocellulose : substrate interactions and high solids loadings." Forest & Landscape, 2008. http://www.sl.kvl.dk/upload/nr_42_phd_jan__web.pdf.

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Zhang, Yu <1987&gt. "Catalytic Upgrading of Oxigenated Building Blocks in Lignocellulose- based Biorefineries." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amsdottorato.unibo.it/7797/1/Thesis%20%20UNIBO%20Yu%20ZHANG.pdf.

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This PhD project is focused on the gas phase hydrogenation of furfural over iron and magnesium oxides. Numerous catalysts with different iron and magnesium molar ratios, were prepared by co-precipitation or impregnation methods and were tested for the reduction of furfural (FU) using methanol as hydrogen donor. Furfuryl alcohol (FAL) and 2-methyl furfural (MFU) were the main products obtained, demonstrating that Mg/Fe/O systems can promote sequential hydrogenation-hydrogenolysis reaction. Impregnated catalysts demonstrated to be more active and selective towards MFU than co-precipitated ones. Reported data demonstrated that product distribution was strongly influenced by the iron content and from the resulting acid and redox properties of the material. As a matter of fact, the introduction of iron on the surface of the basic oxide led to the addition of Lewis acidity and redox capacity in the system, significantly enhancing FU conversion and MFU production. The activation of different species on the catalyst surface has been studied by in situ DRIFTS and FTIR. The results reveal that the MgO basicity favors methanol activation and FeOx redox capacity might be the responsible of furfuryl alcohol hydrogenolysis.

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Daou, Marianne. "Glyoxal oxidases from Pycnoporus cinnabarinus : production, characterization and application." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0088.

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La biomasse végétale est une alternative durable et écologique pour les ressources fossiles. L'exploitation et la valorisation de cette biomasse sont rendues possibles grâce à la capacité naturelle des enzymes fongiques à dégrader et modifier cette biomasse. Parmi ces enzymes, les glyoxal oxydases génératrices de H2O2 (GLOX) restent un groupe peu étudié avec un seul exemple de protéine caractérisée dans la littérature à partir d’un champignon dégradant le bois.Dans cette thèse, trois GLOX, précédemment identifiées dans le génome du champignon dégradant le bois Pycnoporus cinnabarinus (PciGLOX), ont été sélectionnées, produites par voie hétérologue et caractérisées. La caractérisation a révélé des différences entre les trois PciGLOX dans la stabilité des protéines, la spécificité du substrat et l’efficacité catalytique. Les protéines PciGLOX sont produites sous leur forme inactive et leur mécanisme d'activation a été étudié. La capacité des GLOX à catalyser la réaction d'oxydation du 5-hydroxyméthylfurfural (HMF), d’intérêt industriel, a été étudiée pour la première fois dans ce travail. Le HMF a été oxydé par PciGLOX en acide 5-hydroxyméthyl-2-furancarboxylique (HMFCA) comme produit principal. Le HMFCA est difficile à produire par catalyse chimique et est utilisé dans la production de polyesters et de produits pharmaceutiques. PciGLOX ont également été capables de produire l’acide furandicarboxylique (FDCA), qui est un précurseur dans les procédés de production du bioplastique. Ce travail ouvre de nouvelles perspectives pour étudier plus en détail le rôle de GLOX dans la dégradation de la lignocellulose, et dans les applications biotechnologiques
Plant biomass is a sustainable and eco-friendly alternative for fossil fuels. The exploitation and valorisation of plant biomass is possible through biotechnological processes that rely on the natural ability of fungal enzymes to degrade and modify this biomass. Among these enzymes are H2O2-generating glyoxal oxidases (GLOX), which haven’t been extensively studied with only one example in the literature on GLOX from wood-degrading fungi. In this thesis three GLOX, previously identified in the genome of the wood-degrading fungus Pycnoporus cinnabarinus (PciGLOX), were heterologously produced and characterisation. The three PciGLOX showed differences in their stability, substrate preferences and catalytic properties. The ability of GLOX to catalyse the biotechnologically important oxidation reaction of 5-hydroxymethylfurfural (HMF) was investigated for the first time in this work. PciGLOX oxidized HMF to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), which is difficult to produce via chemical catalysis and is used in polyesters and pharmaceutical products production. PciGLOX were also able to oxidize HMF derivatives leading to the formation of the final product furandicarboxylic acid (FDCA), which is a bioplastic precursor. PciGlOX proteins are produced in their inactive form and their activation mechanism was investigated in this thesis. This work opens new prospects to investigate more the role of GLOX in plant biomass degradation and biotechnology, and the possible optimization techniques of the catalytic properties of this enzyme

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Bunhu, Tavengwa. "Preparation and evaluation of Lignocellulose-Montmorillonite nanocomposites for the adsorption of some heavy metals and organic dyes from aqueous solution." Thesis, University of Fort Hare, 2011. http://hdl.handle.net/10353/535.

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The need to reduce the cost of adsorption technology has led scientists to explore the use of many low cost adsorbents especially those from renewable resources. Lignocellulose and montmorillonite clay have been identified as potentially low cost and efficient adsorbent materials for the removal of toxic heavy metals and organic substances from contaminated water. Montmorillonite clay has good adsorption properties and the potential for ion exchange. Lignocellulose possesses many hydroxyl, carbonyl and phenyl groups and therefore, both montmorillonite and lignocellulose are good candidates for the development of effective and low cost adsorbents in water treatment and purification. The aim of this study was to prepare composite materials based on lignocellulose and montmorillonite clay and subsequently evaluate their efficacy as adsorbents for heavy metal species and organic pollutants in aqueous solution. It was also important to assess the adsorption properties of the modified individual (uncombined) lignocellulose and montmorillonite. Lignocellulose and sodium-exchanged montmorillonite (NaMMT) clay were each separately modified with methyl methacrylate (MMA), methacrylic acid (MAA) and methacryloxypropyl trimethoxysilane (MPS) and used as adsorbents for the removal of heavy metals and dyes from aqueous solution. The lignocellulose and NaMMT were modified with MMA, MAA and MPS through free radical graft polymerisation and/or condensation reactions. NaMMT was also modified through Al-pillaring to give AlpMMT. The materials were characterised by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS) and characterisation results showed that the modification of the montmorillonite with MAA, MMA and MPS was successful. The modified lignocellulose and montmorillonite materials were evaluated for the adsorption of heavy metal ions (Cd2+ and Pb2+) from aqueous solution by the batch method. The adsorption isotherms and kinetics of both Cd2+ and Pb2+ onto the NaMMT clay, AlpMMT and lignocellulose materials are presented. The Langmuir isotherm was found to be the best fit for the adsorption of both heavy metals onto all the adsorbents. AlpMMT showed very poor uptake for heavy metals (both Cd2+ and Pb2+). PMMAgMMT, PMAAgMMT, PMAAgLig and PMPSgLig showed improved adsorption for both heavy metals. The mechanism of heavy metal adsorption onto the adsorbents was best represented by the pseudo second-order kinetic model. PMPSgLig, NaMMT and AlpMMT showed relatively high adsorption capacities for methyl orange, while the adsorption of neutral red was comparable for almost all the adsorbents. Neither the Langmuir model nor the Freundlich model was found to v adequately describe the adsorption process of dyes onto all the adsorbents. The pseudo second-order model was found to be the best fit to describe the adsorption mechanism of both dyes onto all the adsorbents. The modification of lignocellulose and montmorillonite with suitable organic groups can potentially produce highly effective and efficient adsorbents for the removal of both heavy metals and dyes from contaminated water. Novel adsorbent composite materials based on lignocellulose and montmorillonite clay (NaMMT) were also prepared and evaluated for the removal of pollutants (dyes and heavy metals) from aqueous solution. The lignocellulose-montmorillonite composites were prepared by in situ intercalative polymerisation, using methyl methacrylate, methacrylic acid and methacryloxypropyl trimethoxysilane (MPS) as coupling agents. The composite materials were characterised by FTIR, TGA, TEM and SAXS. SAXS diffractograms showed intercalated nanocomposites of PMMAgLig-NaMMT and PMAAgLig-NaMMT, whereas PMPSgLig-NaMMT showed a phase-separated composite and the same results were confirmed by TEM. The lignocellulose-montmorillonite composites were assessed for their adsorption properties for heavy metal ions (Cd2+ and Pb2+) and dyes (methyl orange and neutral red) from aqueous solution. Among these composite materials, only PMAAgLig-NaMMT showed a marked increase in the uptake of both Cd2+ and Pb2+ relative to lignocellulose and montmorillonite when used independently. The adsorption data were fitted to the Langmuir and Freundlich isotherms, as well as to the pseudo first-order and pseudo second-order kinetic models. The data were best described by the Langmuir isotherm and the pseudo second-order kinetic model. On the adsorption of dyes, only PMPSgLig-NaMMT showed enhanced adsorption of methyl orange (MetO) compared with lignocellulose and montmorillonite separately. The enhanced adsorption was attributed to the synergistic adsorption due to the presence of MPS, lignocellulose and NaMMT. Competitive adsorption studies were carried out from binary mixtures of MetO and Cd2+ or Pb2+ in aqueous solution. The adsorption process of MetO onto the composite material was found to follow the Freundlich adsorption model, while the mechanism of adsorption followed both the pseudo first-order and pseudo second-order models. This particular composite can be used for the simultaneous adsorption of both heavy metals and organic dyes from contaminated water. The adsorption of neutral red to the composite materials was comparable and the pseudo second-order kinetic model best described the adsorption mechanism.

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Ghizzi, Damasceno da Silva Gabriela. "Fractionnement par voie sèche de la biomasse ligno-cellulosique : broyage poussé de la paille de blé et effets sur ses bioconversions." Thesis, Montpellier, SupAgro, 2011. http://www.theses.fr/2011NSAM0031/document.

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Dans le contexte de la bioraffinerie végétale pour la production de molécules et d'énergie, des prétraitements sont nécessaires pour augmenter la réactivité de la biomasse ligno-cellulosique. Cette thèse s'insère dans une thématique dont l'objectif général est d'établir les bases d'une raffinerie du végétal par des procédés par voie sèche. Cette étude a pour objectif de développer et comprendre le fractionnement mécanique poussé de la paille de blé jusqu'à des tailles sub-millimétriques et d'évaluer les effets sur des procédés de bioconversions énergétiques. La paille de blé présente une grande hétérogénéité à plusieurs niveaux d'échelle (du cm au µm). Un diagramme de broyage multi-étapes à l'échelle pilote (>1kg) a permis d'obtenir une large gamme de tailles de particules, par 3 modes de sollicitation distincts: i) broyages à grille sélective produisant des tailles du grossier (800 µm) au fin (50 µm), ii) broyage à jet d'air (ultrafin, ~20 µm) et iii) broyage à boulets (ultrafin, ~10 µm). Une méthodologie d'analyse morphologique des particules a été développée par analyse d'images de microscopie optique. La paille soumise aux mécanismes complexes de rupture lors de broyages produit une forte variabilité des formes et compositions des particules. L'analyse multiple de co-inertie a permis d'évaluer de façon globale les morphologies des particules. Globalement, le broyage diminue la taille et les facteurs de forme des particules, avec quelques exceptions dues aux configurations matérielles. La dégradabilité enzymatique (saccharification) des poudres produites a été améliorée par la réduction de la taille des particules. Jusqu'à ~100 µm la solubilisation des polysaccharides augmente puis se stabilise à 36 % des polysaccharides totaux et 40 % de la cellulose. Seuls les échantillons issus du broyage à boulets dépassent cette limite et atteignent 46 % d'hydrolyse des polysaccharides totaux et 72 % de la cellulose. Ceci est lié à une augmentation de l'efficacité enzymatique due à la diminution de la cristallinité de la cellulose (de 22 à 13%). Ces résultats du broyage à boulets sont comparables à ceux de l'explosion à la vapeur, avec une meilleure préservation des hémicelluloses. Cette amélioration d'efficacité enzymatique s'est traduite par des dégradations anaérobies (biogaz) accélérées et légèrement augmentées (cas du broyeur à boulets). La décomposition aérobie dans le sol a été améliorée par le broyage grossier, mais les broyages plus fins n'ont pas entrainé de gain. Les caractéristiques de la paille broyée peuvent varier selon l'intensité et le mode de broyage. Bien que tous les broyages permettent la réduction de la taille, le broyage à grilles et le broyage à jet d'air n'engendrent pas de changements dans la structure fine des polymères pariétaux. Seul le broyage à boulets a engendré des changements de la structure interne des particules notamment en réduisant la cristallinité de la cellulose et en solubilisant partiellement les hémicelluloses. Ces résultats permettent de mettre en évidence que la fragmentation mécanique poussée par voie sèche est une alternative possible aux prétraitements utilisés en raffinerie végétale
In a context of plant biorefinery for the production of molecules and energy, pretreatments are necessary to increase the reactivity of the lignocellulosic biomass. This thesis is part of a general project aiming to establish the bases for a dry plant refinery. This study aimed to develop and understand advanced mechanical fractionation of wheat straw down to sub-millimeter sizes and to assess its effects on bioconversion processes for bioenergy. Wheat straw exhibited a high heterogeneity at several scale levels (from cm to μm). A multistep diagram of dry grinding at pilot-scale (> 1 kg) produced a wide range of particle sizes by three distinct mode of action: i) sieve-based grinding producing particle sizes from coarse (800 μm) to fine (50 μm), ii) air-jet milling (ultra-fine, ~ 20 μm) and iii) ball milling (ultra-fine, ~ 10 "m). A morphological analysis of particles was developed by image analysis from light microscopy. Subjecting wheat straw to the complex breaking mechanisms during grinding produced particles highly variable in shapes and compositions. A multiple co-inertia analysis allowed the evaluation of the overall particle morphologies. Generally, grinding reduced the size and shape descriptors of particles, with some exceptions due to equipment configurations. The enzymatic degradability (saccharification) of produced powders was improved by reducing their particle size. Until ~ 100 μm the polysaccharides solubilisation was increased and then stabilised at 36% total polysaccharides and 40% cellulose. Only samples from ball milling overcome this limit and attained hydrolysis yields of 46% total polysaccharides and 72% cellulose. This is due to an increase in enzymatic efficiency by the reduction of cellulose crystallinity (from 22 to 13%). These results of ball milling are comparable to those of steam explosion process, with a better preservation of hemicelluloses. This improved enzymatic efficiency resulted in faster and slightly more extensive (ball milling case) anaerobic degradations (biogas). Aerobic decomposition in the soil was improved by coarse grinding, but finer grinding did not result in a further increase. The characteristics of ground straw varied depending on grinding intensity and mode. Although all grindings could reduce the size, sieve-based grinding and air-jet milling did not allow changes in the fine structure of cell wall polymers. Only ball milling led to changethe internal structure of particles especially reducing cellulose crystallinity and partially solubilising hemicelluloses. These results demonstrate that advanced mechanical fragmentation by dry processes is a possible alternative for pretreatments in a plant refinery

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41

Barkhau, Robert A. "The preparation, characterization, and condensation reactions of polymer-supported lignin models." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/5643.

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Bennini, Souad. "Mise au point d'une méthode d'analyse des mécanismes de pyrolyse du bois à haute température à l'aide de matériaux marqués." Toulouse 3, 1989. http://www.theses.fr/1989TOU30147.

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Le travail presente s'inscrit dans une thematique visant a la valorisation de la biomasse vegetale a des fins energetiques. La methode de valorisation choisie est la pyrolyse-flash qui conduit a des gaz combustibles. La maitrise des processus de gazeification, en particulier en vue de l'obtention de gaz propres, necessite une meilleure connaissance des mecanismes de rupture des macromolecules vegetales. Une methode originale d'etude de ces mecanismes est developpee dans ce travail. Elle met a profit la possibilite d'obtenir des lignocelluloses marquees selectivement au niveau de la lignine au cours de la sa biosynthese grace a l'incorporation de divers precurseurs marques. La degradation thermique des lignocelluloses est obtenue par pyrolyse-flash au four a image. L'analyse de la repartition des atomes marques dans les produits de pyrolyse a permis de montrer que la lignine est fortement impliquee dans la formation des goudrons; la part gazeifiee est formee principalement d'hydrogene, d'oxyde de carbone et de methane. La faisabilite de la methode a ete etalie dans des conditions accessibles a l'experimentation au laboratoire. Les conditions de gazeification optimale ont ete determinees et un schema de comportement des echantillons base sur l'application d'un modele thermique simple est propose

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Munns, Craig Christopher Robert. "Development of physio-chemical pretreatments and mixed microbial cultures for the conversion of lignocellulosic biomass to useful products." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28768.

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There is increasing interest in producing biofuels; biofuels are preferable to fossil fuels as the biomass from which they are derived is seen as a renewable source, as opposed to fossil fuels which are a finite resource. “First Generation” biofuels are derived from food crops such as grains and sugar cane. The use of food crops is not sustainable in this age of increasing food insecurity. A promising alternative appears to be what is termed “Second Generation” feedstocks, such as energy crops like Miscanthus spp., and agricultural by-products. The problem with the use of second generation feedstocks is firstly that the sugars are locked up in the cell wall polymers (CWP), which need to be released by physio-chemical pre-treatments, that are costly and time consuming. The second problem is that not all the sugars that are released from CWP are able to be utilised by wild type product-forming organisms. However, model chassis organisms can be genetically modified to utilise these sugars and /or produce enzymes to degrade biomass which reduces the time and costs involved in the process. While engineering these organisms to utilise a range of monosaccharides has already been successful, engineering them to produce degradation enzymes is proving to be problematic. A potentially more effective system is to use co-cultures of both cellulose-degrading and product-forming organisms. Since this is a novel approach it is not known whether the two organisms are able to live together without any adverse effects. The aims of this study were firstly to determine whether mixed cultures of both cellulose-degrading and potential product-forming organisms could survive in the presence of one another, secondly whether the cellulose-degrading organisms could degrade potential feedstock down into their monosaccharide building blocks and thirdly whether the potential product-forming organisms could survive and utilise these monosaccharides for growth and potential fermentation. It was discovered that C. hutchinsonii can degrade both paper and Triticum aestivum straw polymers into their monosaccharide components and that B. subtilis can survive on the sugars released by C. hutchinsonii. It was also discovered that C. hutchinsonii and B. subtilis 168 can only tolerate an ethanol concentration of up to 2% (v/v) and that this is below the baseline for a biofuel system to be economically viable. Likewise, C. hutchinsonii and B. subtilis 168 have an even poorer tolerance for butanol; growth is inhibited by < 1% butanol in its growth media. A series of physio-chemical pre-treatments were developed in order to make the monosaccharides present in the cell wall polymers more accessible to microbial saccharification. Sequential pre-treatments, both physical milling and chemical hydrolysis in tandem, had the greatest effect on the bio chemistry of the biomass, but that these physio-chemical pre-treatments produced inhibitory compounds in the medium that retarded microbial growth. Attempts were made to genetically modified Bacillus subtilis 168 to produce lactic acid and ethanol by over expressing the native ldh gene under the highly-expressed promoter of the cspD gene and by integrating the fused pdc:adh gene from Z. mobilis under the same promoter. Transformation of B. subtilis to over express LDH was successful, with PCR confirmation of the correct insertion and enzyme activity for the ldh both in vitro and in vivo, with the latter producing more lactic acid aerobically than the wild type. Transformation of B. subtilis to express pdc:adh and subsequent production of ethanol was not successful.

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Bey, Mathieu. "Etude d’une CDH et de glycosyl hydrolases de la famille 61 : Implication dans les processus de dégradation des lignocelluloses." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4719.

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En réponse aux préoccupations environnementales, les procédés industriels comme la production de bioéthanol de deuxième génération sont apparus. Basés sur la conversion enzymatique de la cellulose, ces processus font face à un problème majeur, la réticence de la biomasse lignocellulosique à l'hydrolyse. Afin de résoudre ce problème et celui lié aux coûts d'utilisation de cocktails de cellulases, les recherches se sont axées sur diverses méthodes permettant d'augmenter l'hydrolyse de la cellulose. Les champignons filamenteux sont connus pour être des dégradeurs naturels du bois et, par conséquent, sont utilisés dans de nombreuses applications biotechnologiques. Récemment, quelques études ont révélé l'importance d'enzymes fongiques telles que la CDH et les GH61 dans la dégradation oxydative de la lignocellulose. Les travaux réalisés au cours de cette thèse ont permis de démontrer l'importance de ces enzymes oxydatives dans les phénomènes de déconstruction de la lignocellulose. L'utilisation de ces enzymes oxydatives offre de réelles voies d'amélioration de la production de bioéthanol et de compréhension de la dégradation in vivo des lignocelluloses par les champignons
In response to environmental concerns, industrial processes such as second generation bioethanol production have emerged. Based on enzymatic cellulose conversion, these processes are confronted with a major problem, the recalcitrance of lignocellulosic biomass. To solve the problem caused by substrate recalcitrance and high cost of cellulase cocktails, research has focused on various methods to enhance cellulose hydrolysis. Fungi are known to be natural degraders of wood and consequently are used in derived biotechnological applications. Recently, several studies have revealed the importance of fungal enzymes such as GH61 and CDH in the oxidative degradation of lignocellulose. During the work done on this thesis, we demonstrated implication of these oxidative enzymes in lignocellulose deconstruction to enhance hydrolysis performed by more classical cellulases. Utilization of oxidative enzymes offers a suitable way for bioethanol processing enhancement and comprehension of the in vivo lignocellulosic degradation by fungi

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45

Nystrand, Christoffer. "Feasibility of lignocellulose as feedstock for biological production of super absorbent polymers." Thesis, Linköpings universitet, Teknisk biologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-60743.

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Super absorbent polymers (SAP) can absorb liquid many times its own weight and is used in diapers and incontinence pads. The most common type of SAP is cross-linked polyacrylic acid. The production of acrylic acid uses crude oil as starting material. This means that the final price of acrylic acid is affected by the price of crude oil which is expected to rise. This has led to an increasing interest in developing a sustainable bioproduction process that uses renewable lignocellulosic raw material for the making of acrylic acid. Lignocellulose is the material that plants and trees consist of and it contains big amounts of sugar. Sugar molecules in lignocellulose can serve as substrate for microorganisms that can transform them into 3-hydroxipropionic acid, which in turn can be converted to acrylic acid. In order to use the sugar molecules from lignocellulose, some type of pretreatment is required. However, the pretreatments that are available today are not efficient enough to be applied on a large scale and some also cause the formation of microbial inhibitors. The microbial conversion of sugar to 3-hydroxipropionic acid do not show sufficient efficacy so far, but the process is under development and improvements are regularly made. Furthermore would it be advantageous if polymerization of acrylic acid could be made directly in the fermentation broth without any energy consuming separation stepsAttempts to polymerize acrylic acid in fermentations broths from yeast have been performed. The SAP properties; absorption capacity, absorption capacity under pressure and gel strength were evaluated by methods commonly used in the hygiene industry. These characteristics are important if the SAP is to be used in diapers and incontinence pads. To examine what compounds in the fermentations broth that affected the polymerization process and SAP properties, an experimental design was made. With help of the design quantitative and statistical methods were used to determine which compound had an impact. Four groups of compounds were selected for examination; sugars, alcohols, acids and aromatic compounds. The results of the experiments conducted showed that it is possible to polymerize SAP in fermentation broth from yeast using acid pretreated spruce as sugar source. The characterization showed that the absorption capacity was unchanged while the gel strength deteriorated significantly. It was also noted that SAP polymerized in fermentations broths had strong colors in contrast to conventional SAP, which is white. Qualitative and statistical analysis showed that the aromatic compounds affected the polymerization and SAP properties negative.

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Tuncer, Munir. "A study of the enzymology of lignocellulose degradation by Thermomonospora fusca BD25." Thesis, University of Essex, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285863.

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Mousa, A., G. Heinrich, and U. Wagenknecht. "Thermal properties of carboxylated nitrile rubber/nylon-12 composites-filled lignocellulose materials." Sage, 2014. https://tud.qucosa.de/id/qucosa%3A35546.

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Organic hybrid composites based on carboxylated nitrile rubber and nylon-12 reinforced with mercerized and diisocyanated lignocellulose residue (LCR) was prepared. The influence of the LCR on the viscoelastic properties of these organic hybrids was investigated by dynamic mechanical analysis and thermal analysis (differential scanning calorimetry (DSC)). It is found that either the position of the damping peak was shifted to higher values or the intensity of the damping peak was significantly increased with LCR. These results could imply that the LCR enhanced the damping properties of the composites. The thermal stability of the composites was evaluated with the mean values obtained using thermogravimetrical analysis. The decomposition rate was investigated using differential thermal gravimetry. The crystallization behavior of the prepared composites was checked by DSC.

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Sandeep, Pareek. "DEGRADATION OF LIGNOCELLULOSE UNDER ANAEROBIC CONDITIONS : THE EFFECT OF SULFATE REDUCING BACTERIA." Kyoto University, 2000. http://hdl.handle.net/2433/180922.

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Eborall, William Scott. "Discovering novel lignocellulose degrading enzymes from the marine wood borer, Limnoria quadripunctata." Thesis, University of York, 2013. http://etheses.whiterose.ac.uk/5152/.

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Transportation accounts for a large proportion of global CO2 emissions, estimated at 22% of all anthropogenically produced CO2 in 2010, with most of this coming from the use of liquid transportation fuels. Second generation biofuels offer a sustainable opportunity to decarbonise this sector of global energy use. To realise the potential of second generation biofuels more efficient methods of deconstructing their lignocellulosic starting material must be developed. Understanding how the marine wood borer, Limnoria quadripunctata, is able to do this biochemically without the assistance of microbial symbionts may inspire new techniques to achieve this in an industrial setting. Whilst the anatomy of Limnoria has been well studied, and the transcriptome of its hepatopancreas (HP), a secretory organ of the digestive system, has been previously elucidated, little is known about how the animal is able to derive nutrients from its diet of wood without the aid of microbial symbionts. In this work a proteomic study of the HP and gut tissue of Limnoria was carried out and the data generated analysed in concert with that of the HP transcriptome to identify proteins which may be involved in lignocellulose digestion in the animal. In this way the glycosyl hydrolases, hemocyanins (HCs), ferritins and leucine rich repeat proteins were identified as having the potential to be involved in lignocellulose digestion. Work was undertaken to characterise the function of HC proteins in Limnoria. Reverse transcriptase quantitative polymerase chain reaction analysis showed all five Limnoria HC genes to be solely expressed in the HP, whilst Western blot and proteomic examination showed HC protein to be present in the HP and gut, as well as the rest of the body. This indicates that HCs are transported post translation to the gut, the site where ingested wood particles are segregated and presumably digested. In vivo experiments suggested that a phenoloxidase enzyme activity was associated with the production of peroxides in the gut of Limnoria. Using a soluble extract of Limnoria tissue a di-phenoloxidase (DPO) enzyme activity was demonstrated which it was possible to inhibit using a phenoloxidase inhibitor. Mass spectrometry analysis implicated HC protein as the species responsible for this activity. Multiple sequence alignment showed that the Limnoria HC sequences possess the conserved features associated with the ability to carry out a DPO enzyme activity described in HC proteins from other arthropod species. Attempts were made to heterologously express Limnoria HC proteins in a number of systems with limited success being achieved using the ArcticExpress strain of Escherichia coli. Partially pure heterologous protein produced in this way was able to show a DPO enzyme activity which was inhibited by a phenoloxidase inhibitor. Mass spectrometry analysis implicates HC as the protein species responsible for this activity. Based on the findings of this work it seems possible that the hemocyanin proteins of Limnoria aid the animal in digesting wood by contributing to the formation of reactive peroxide compounds in its gut which attack lignocellulose. This process may also contribute towards the sterility of the gut by creating an inhospitable environment for microbial colonisation. Further work is now required to determine the mechanisms by which it occurs.

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Cagnin, Lorenzo. "Engineering robust Saccharomyces cerevisiae yeast for consolidated bioprocessing of lignocellulose into bioethanol." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3422878.

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Second generation bioethanol, making use of the polysaccharides included in the lignocellulosic biomass, represents a promising alternative approach to overcome the limitations revealed by first generation bioethanol. The main issue hindering the effective industrial scale utilization of biomass is the lack of low-cost technology. In fact, lignocellulose hydrolysis requires expensive pre-treatments and large dosages of commercial enzymes. Moreover, feedstock pre-treatment results in the formation of inhibitors, mainly weak acids (acetic and formic), furans (furfural and 5-hydroxymethyl-2-furaldehyde) and phenolics, which affect the fermentation phase. Consolidated BioProcessing (CBP) of lignocellulosic biomass is gaining increasing attention as a potential strategy to reduce production costs both by integrating different production steps and by lowering the need for supplying of commercial cellulases. As no naturally occurring fermenting microorganism suitable for CBP has been described yet, genetic engineering of highly fermentative microorganisms, particularly yeast, will be required. To further improve the economic feasibility of the process in industrial scenarios, the search of robust yeast with high inhibitors tolerance as platform for genetic engineering would be desired. In this study, a collection of wild type Saccharomyces cerevisiae yeast, previously selected for their robustness and high ethanol yield, was characterized for inhibitors tolerance on synthetic mixtures of the inhibitors typical of lignocellulosic pre-hydrolysates and on real pre-hydrolysates, rich in these toxic compounds. The best performing strain was chosen as a robust candidate for the expression of three fungal β-glucosidases by δ-integration, together with the benchmark strain Ethanol Red®, currently utilized in industrial bioethanol production. Similarly, two wild-type yeast that were previously successfully used as parental to develop CBP strains, were used for the same purpose. Among the cellulases required for cellulose degradation, β-glucosidase was selected as it plays a key role in the process, representing the rate limiting enzyme. A large amount of recombinant clones, secreting β-glucosidases from the fungal species Saccharomycopsis fibuligera and Phanerochaete chrysosporium, were obtained. The engineered clones were firstly screened for high enzyme activity in a quantitative assay, using esculin as substrate. The β-glucosidase activity of the best performing strains was then quantified on pNPG. One recombinant able to produce high amounts of β-glucosidase demonstrated to be mitotically-stable and capable of sustaining the growth in presence of cellobiose as sole carbon source. The enzymatic activity of the recombinant was characterized in vitro in terms of enzyme localization, optimal pH and temperature, and stability. The fermentative abilities were assessed in defined medium containing cellobiose. The obtained recombinant showed comparable performances to the parental strain on glucose, indicating that β-glucosidase secretion does not cause any severe metabolic burden to the host. Further, the engineered strain could display high ethanol yield when fermenting cellobiose, comparable to those of a laboratory yeast strain expressing the same β-glucosidase via multicopy episomal plasmid, despite the remarkable disadvantage of lower gene copy number guaranteed by gene integration. This study reports the successful construction of S. cerevisiae strains capable of tolerating high inhibitors concentrations and expressing fungal β-glucosidases. To our knowledge, this work represents the first attempt to produce a CBP microorganism for lignocellulosic bioethanol via integration of β-glucosidases into tolerant yeast selected for thermotolerance and resistance to the inhibitors typically present in lignocellulosic pre-hydrolysates. The fermentation performances of the engineered strain will next be studied on sugarcane bagasse hydrolysate, with the aim to confirm the inhibitors tolerance traits.
Il bioetanolo di seconda generazione rappresenta un approccio particolarmente promettente per superare le limitazioni intrinseche del bioetanolo di prima generazione, grazie all’utilizzo dei polisaccaridi presenti nelle biomasse lignocellulosiche. Il principale aspetto che ostacola l’utilizzo in scala industriale della biomassa è rappresentato dalla mancanza di soluzioni tecniche a basso costo. L’idrolisi della lignocellulosa richiede infatti l’impiego di costosi pre-trattamenti e di consistenti quantità di enzimi commerciali. Inoltre il pre-trattamento della biomassa causa la formazione di inibitori, principalmente acidi deboli (acidi acetico e formico), furani (furfurale e 5-idrossimetil-furfurale) e fenoli, che hanno un effetto negativo sulla fase di fermentazione. Il Consolidated BioProcessing (CBP) della biomassa lignocellulosica sta suscitando crescenti attenzioni quale strategia per la riduzione dei costi di produzione, grazie all’integrazione di processi produttivi comunemente distinti e alla riduzione delle quantità degli enzimi commerciali richiesti. Poiché non è ancora stato descritto alcun microrganismo con capacità fermentative in possesso delle caratteristiche necessarie per il CBP, risulta necessario ingegnerizzare microrganismi in possesso di elevate performance fermentative. Al fine di favorire ulteriormente l’applicabilità di questo approccio in ambito industriale, i lieviti da sottoporre al processo di ingegnerizzazione dovranno essere preventivamente selezionati in base alla capacità di tollerare alte concentrazioni di inibitori. In questo lavoro una collezione di lieviti wild-type di Saccharomyces cerevisiae, precedentemente selezionati per robustezza ed elevato tenore fermentativo, è stata caratterizzata per la capacità di tollerare miscele sintetiche degli inibitori tipicamente presenti in nei pre-idrolizzati di origine lignocellulosica. Gli stessi lieviti sono inoltre stati valutati, per le stesse caratteristiche, in pre-idrolizzati non sintetici, ricchi in questi composti. Il ceppo in grado di mostrare le migliori prestazioni è stato scelto per l’espressione di tre β-glucosidasi fungine mediante δ-integrazione, assieme al ceppo di riferimento Ethanol Red®, attualmente utilizzato per la produzione industriale di bioetanolo. Analogamente, sono stati selezionati per lo stesso scopo due lieviti wild-type in precedenza utilizzati con successo per lo sviluppo di ceppi CBP. Tra le cellulasi necessarie per degradare la cellulosa, la β-glucosidasi rappresenta il fattore limitante nel processo, ricoprendo dunque un ruolo chiave nello stesso. E’ stato ottenuto un elevato numero di cloni ricombinanti in grado di secernere β-glucosidasi delle specie fungine Saccharomycopsis fibuligera e Phanerochaete chrysosporium. I cloni ingegnerizzati sono stati in primo luogo selezionati per l’elevata attività enzimatica in un saggio di tipo qualitativo, utilizzando esculina come substrato. L’attività β-glucosidasica dei ceppi più performanti è stata in seguito quantificata su pNPG. Un clone ricombinante, in grado di produrre elevate quantità di β-glucosidasi, è risultato essere mitoticamente stabile e in grado di crescere in presenza di cellobiosio come unica fonte di carbonio. L’attività enzimatica del ricombinante è stata caratterizzata in vitro, relativamente a localizzazione dell’enzima, temperatura e pH ottimali, e stabilità. Le capacità fermentative sono state valutate in presenza di un mezzo di crescita definito contenente cellobiosio. Il ricombinante così ottenuto ha mostrato performance paragonabili a quelle del ceppo parentale in presenza di glucosio, ad indicare che la secrezione di β-glucosidasi non comporta alcun sensibile peso metabolico per l’ospite. Inoltre, il ceppo ingegnerizzato ha mostrato un’elevata resa in etanolo da cellobiosio, paragonabile a quella mostrata da un ceppo di laboratorio in grado di esprimere la medesima β-glucosidasi mediante plasmide episomale multicopia, nonostante il considerevole svantaggio dato dal minor numero di copie geniche permesso dal processo di integrazione cromosomica. Questo studio riporta la costruzione di ceppi di S. cerevisiae in grado di tollerare alte concentrazioni di inibitori e di esprimere β-glucosidasi di origine fungina. In base alla nostra conoscenza, questo lavoro rappresenta il primo tentativo di ottenere un microrganismo CBP per la produzione di bioetanolo di origine lignocellulosica mediante l’integrazione di β-glucosidasi in lieviti selezionati per termotolleranza e per la resistenza agli inibitori comunemente presenti nei pre-idrolizzati lignocellulosici. Le performance fermentative del ceppo ingegnerizzato saranno successivamente studiate su pre-idrolizzato di bagassa di canna da zucchero, al fine di confermare le caratteristiche di tolleranza agli inibitori.

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Dissertations / Theses on the topic 'Lignocellulose'

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