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1
Guzman-Juarez, M. "Yeast protein products : Preparation, characterisation and functional properties." Thesis, University of Reading, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376661.
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Klimaitė, Jūratė. "Karvių sergančių slaptuoju mastitu diagnostika, gydymas ir profilaktika." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050926_152516-82961.
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The distribution of yeast fungi has been ascertained as their influence on SCM etiology. Our developed preparation for treatment for yeast and microbe caused mastitis “Gentafung” is composition of wide spectrum antibiotics and antifungal medications. An evaluation was performed of commercially available homeopathic preparations in treating SCM. A new recommended preparation “OrbeScal” was evaluated for drying cows. A comparison of Candida genus commercial identification systems diagnostic accuracy was via classical methods.
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TIMMERMAN, JOHANNA. "Preparation and structural study of the dna-binding domain of the cyp1 protein of the yeast saccharomyces cerevisiae." Paris 11, 1994. http://www.theses.fr/1994PA112429.
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Dans la levure saccharomyces cerevisiae, la proteine cyp1 est un regulateur de la transcription de nombreux genes dont l'expression est dependante de l'oxygene. Nous nous sommes interesse a la determination de la structure tridimensionnelle du domaine de fixation a l'adn de cette proteine. Cette partie contient un motif cys-xaa(2)-cys-xaa(6)-cys-xaa(6)-cys-xaa(2)-cys-xaa(8)-cys, que l'on retrouve dans de nombreuses proteines de levure interagissant avec l'adn, en particulier dans la proteine gal4. Le but a long terme est de determiner le complexe cyp1-adn par resonance magnetique nucleaire. Dans ce travail nous presentons le clonage et l'expression dans escherichia coli des quatre fragments differents correspondant a la partie n-terminale de l'activateur cyp1 responsable de la fixation a l'adn. Le fragment cyp1(49-126) a ete choisi pour une etude structurale par resonance magnetique nucleaire. Pour ce fragment, un protocole de purification a ete mis au point. Nous montrons ensuite que le zinc est un element essentiel de la structure de la proteine et que le fragment cyp1(49-126) possede 2 atomes de zinc. Les memes resultats ont ete observes lorsqu'on substitue deux atomes de zinc par les atomes cadmium 113. Par resonance magnetique nucleaire, nous avons demontre que les six cysteines du motif ligandent les deux atomes de cadmium. Le fragment a ete ensuite marque avec de l'azote 15. L'ensemble des experiences rmn homonucleaires a deux dimensions (cosy, tocsy et noesy) et heteronucleaires a deux et trois dimensions (hmqc, noe-hmqc, hohaha-hmqc) a permis l'attribution de la partie n-terminale de cyp1(49-126). Les donnees experimentales obtenues par ces experiences ont ete utilisees dans des programmes de modelisation, diana et x-plor. Une structure tridimensionnelle du fragment a pu etre presentee et montre que notre fragment est replie en cluster a zinc
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Merrill, Melissa L. "The ability of a yeast-derived cell wall preparation to minimize toxic effects of high-alkaloid tall fescue straw in beef cattle /." Connect to this title online, 2007. http://hdl.handle.net/1957/4044.
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Riordan, Cathal G. "Studies on brewery yeast preparations for environmental bioremediation." Thesis, University of Ulster, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274562.
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Cool, Marc. "Etude des gènes codant pour le facteur d'élongation EF-1 alpha de levure : isolement et analyse du gène TEF2, contribution à la construction de vecteur d'expression de gène hétérologue à la levure." Paris 6, 1986. http://www.theses.fr/1986PA066363.
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Brümmer, Mieke. "The effect of yeast cell wall preparations on salmonella colonisation, gastrointestinal health and performance of broiler chickens." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-04212008-112014.
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Tan, Xiao. "DISCOVERY OF SELECTIVE PROBES TARGETING RNA POLYMERASE I." UKnowledge, 2019. https://uknowledge.uky.edu/chemistry_etds/113.
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RNR Polymerase I (RNA Pol I) is a “factory” that orchestrate the transcription of ribosomal rRNA for constructing ribosomes as a primary workshop for protein translation to sustain cell growth. Misregulation of RNA Pol I can cause uncontrolled cell proliferation, which leads to the development of cancer. Yeast (Saccharomyces cerevisiae) is a valuable model system to study RNA Pol I. Recently, the X-ray crystal structure of the yeast homologue of RNA Pol I was elucidated, offering the structural basis to selectively target this transcriptional machinery. The approach to selective RNA Pol I targeting was to disrupt the interaction between a specific transcription factor, RRN3 that bind distinct regions of RNA Pol I. For this purpose, a recombined plasmid was designed to carry human rDNA plus its promoter as target together with a selection marker gene. Therefore, this plasmid could not only introduce the target gene into the yeast (host), but also facilitate the passage of this target gene into a stable yeast strain. In this project, one uracil deficient yeast strain of YBR140C was transformed with the recombined yeast integrative plasmid of pHmrDNA-YIPlac211-TG1. This is a recombined plasmid containing not only the human rDNA but also the URA3 gene as a selection marker. PCR amplification of the human ribosomal DNA was indicative of successful integration of the human ribosomal DNA into the genome of the two yeast strains. Virtual screening using a library of 700 FDA-approved compounds was docked into the RRN3-RNA Pol I complex to identify small molecule disruptors of the RRN3-RNA Pol I as a selective strategy. Using growth assays, gel electrophoresis and transcriptional assays, we identified cerivastatin sodium as a lead virtual hit. The result implicates cerivastatin sodium as a selective RNA Pol I inhibitor worthy of further development with potential as targeted anticancer therapeutic.
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Nyman, Jonas, and Michael Lacintra. "Co-cultures of Yeasts and Zygomycetes in the Form of Pellets Methods for the Preparation of Pellets and Biocapsules, Their Properties and Applications." Thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-17277.
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Many industrially important fungi can grow in the form of small spherical pellets.Such pellets reduce the viscosity and enhances mass transfer rates in culture broths.The pelleted morphology also influences the fungus’s metabolism, directing it tospecific metabolites. The pellets are easily harvested from the broth and recycled.These properties makes pelleted morphology very attractive.The pelleted morphology of four Zygomycetes strains was studies. Several differentnutrient media used by other researchers for achieving pelleted growth was tested.The influence of eight factors on pelletization of Rhizopus sp. in a completely definedmedium was determined using a fractional central composite design and logistic regression.Pelleted growth of all four Zygomycetes was achieved, with very good results for twoRhizomucor sp. strains. A simple medium containing calcium carbonate was foundto induce pelletization with very high reproducibility.Immobilization of yeast cells was attempted in pellets of Rhizomucor. It was foundthat a flocculating yeast can be immobilized inside pellets of fungal mycelium, forming”biocapsules”. This is accomplished by first using a medium that induces pelletizationof the filamentous fungus and does not allow for growth of the yeast. Thepellets are then inoculated into a second medium that induces growth and flocculationof the yeast and inhibits further growth of the filamentous fungus.Non-flocculating yeasts could not be immobilized, suggesting that the flocculin proteinsin the cell wall of flocculating strains are important for proper immobilization.The flocculation and immobilization arises due to expression of several differentFLO-genes and the importance of these genes for successful immobilization isdiscussed.The results demonstrate that the morphology of Zygomycetes can be controlled andthat this may be useful in industrial fermentation. The new immobilization techniquereveals the great importance of flocculation and cell surface hydrophobicity. Usingyeast strains that express certain FLO-genes may be beneficial in fermentation oflignocellulosic hydrolysates.Microscopy techniques were developed that allows for high quality microphotographyof pellets and thin cross-sections of pellets and biocapsules.Program: MSc in Resource Recovery - Industrial Biotechnology
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Zechmeisterová, Lucie. "Faktory ovlivňující kvalitu červeného vína." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216207.
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In my thesis, I focused on monitoring of microorganisms in the sample of red grape juice and on the interactions between yeasts, bacteria and filamentous fungi. Three different media were applied for the cultivation of microorganisms; firstly for monitoring of total volume of microorganisms, secondly for yeasts and third time for lactic acid bacteria. The indirect method was used for the determination of the amount of viable cells. This method consists in enumerating of visible macroscopic colonies grown up on agar plates. When the cells grew up, the forms of colonies were analyzed visually and the morphology of microorganisms was detected microscopically. The operating time of enzymes in grape juice in the production of red wine was monitored after application of commercial enzymatic preparation. The enzym action in grape juice was observed on the basis of the process of degradation of high – molecular substrate by enzymes through the use of Ubbelohd´s viscometer. The research findings provided a lot of knowledge about the occurance of microflora in the process of production of red wine. The commercial preparations added to grape juice played a significant role.
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CHEN, CHIA-LING, and 陳佳綾. "The Preparation of Ferrous Ion-enriched Yeast Having Reduced Form of Glutathione." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/26c84r.
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Chang, Ni-Hsuan, and 張倪瑄. "Antigen preparation and application of yeast-expressed classical swine fever virus glycoprotein Erns." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/m3ww24.
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碩士國立中興大學
微生物暨公共衛生學研究所
106
Classical swine fever virus (CSFV) infection causes a highly contagious and often fatal disease in the pig industry worldwide. The CSFV envelope glycoprotein Erns possesses RNase and is able to activity induce humoral immune response. Recombinant CSFV Erns protein has been used as antigen in serodiagnostic tests to detect antibody specific to Erns. Thus, enhancing expression of secreted recombinant Erns is important for developing efficient diagnostic methods. In this study, the short-length Erns recombinant protein named yErns 101-158, which represent the amino acid residues 101-158 and possesses antigenic domains was expressed in yeast Pichia pastoris. To increase the secretion level of expressed protein, the culture medium was supplemented with different concentrations casamino acid (CAA) and dextran sodium sulfate (DSS) and induced at 20℃or 30℃. Expression of yErns 101-158 was characterized by western blot and indirect enzyme-linked immunosorbent assay(indirect ELISA). The result indicated that culture medium with 1% CAA and 0.01% DSS at 30℃could increase the secretion level of expressed yErns101-158 protein. Furthermore, the yErns 101-158 was used as an antigen to develop the yeast-expressed Erns subunit(yErns 101-158) based indirect ELISA for detecting swine antibody to Erns. The assay demonstrated a high sensitivity(82.81%) and specificity(85.19%) when compared with a commercial QIAGEN pigtype CSFV Antibody ELISA kit for detecting 91 swine serum samples. These results will provide research tools and diagnostic reagents for studies and controls of CSFV.
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Chau, Chun-fu, and 趙俊富. "The effect of medium composition in preparation of glucose tolerance factor with yeast fermantation study." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/86437450627946268278.
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碩士國立雲林科技大學
化學工程與材料工程系碩士班
100
Sugar cane syrup is one of the main byproduct of sucrose production. It is rich in carbohydrate organic substances, vitamins and amino acids. Sugar cane syrup contains 40 percent of sucrose and the remaining 60 percent is vitamins, micronutrients and other useful components. Although the cost is low, it could not be absorbed by human body. Therefore, it is not sold for private use but commonly used in cultivation industry or even used to cultivate yeasts. This research has of two main focuses: the ingredients of growth medium and the production of yeast extract. For the growth medium, we first use syrup as our main carbon source and further investigate with single nitrogen source, micro elements and phosphate. When the concentration of syrup in the growth medium reaches 150g/L, the concentration of fungi was relatively higher. We then added single nitrogen source, ammonium sulfate, and urea. As we increase the amount of ammonium sulfate to 3g/L, the ratio of carbon and nitrogen would become 50:1. At this time, we achieved the maximum concentration of fungi which results in increase of yeast extract production. Even though the concentration of fungi when we added Urea is almost the same as ammonium sulfate, the amount of yeast extract we gained was evidently high. T The optimum result is gained when the carbon nitrogen ratio or syrup to urea ratio is 50:1. Since yeast extract contains GTF and of which chromic chloride were added to originally contained chromium to make the source of nutrient. I In the growth medium at the carbon nitrogen ratio of 50:1 with 0.3g/L of metallic element, chromic chloride, the concentration of fungi merely differs by a little but the amount of yeast extract noticeably increased from 0.23g in growth medium of only syrup and urea to as much as 0.25g. This indicates that glucose tolerance factor was transformed from saccharomyces cerevisiae. The formula for growth medium to provide the best condition for this transformation is when carbon, nitrogen, metallic elements are at 15:0.3:0.03.
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Yu, Shu-Fen, and 尤淑芬. "Stuides on screening of yeast and acetic acid bacteria and preparation methods in onion vinegar fermentation." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/02814994146518422159.
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碩士國立中興大學
食品科學系
92
Abstract The objectives of this study were to investigate the alcohol and acetic acid fermentations using the sterile onion(Allium cepa L.) juice as raw material and performed by traditional static cultivation system. This included screening of yeast strain and acetic acid bacteria strain, and establishment of the conditions for onion vinegar fermentation process. Allysine compounds present in onion have a keen, stimulating smell and an anti-bacterial property, which inhibits the growth of yeast. In preliminary experiments, difficulty was experienced in fermenting the raw onion juice using yeast. However, since the allysine compounds are volatile and they can be removed by autoclaving. Alcohol and acetic acid fermentations using the sterile onion juice were thus performed successfully by batch culture. Saccharomyces cerevisiae CCRC 21551 was chosen for its best alcohol producing capability, up to 14.1%(v/v) was obtained, while S. cerevisiae 20262 was best for its special fruit flavor . These two strains were chosen to study the subsequent determination of optimum condition of alcohol fermentation. Acetobacter sp. CCRC 12326 was chosen to study the optimum condition of acetic acid fermentation. The acetic acid producing capability of this strain was up to 4.86% (v/v) in mannitol medium containing 5% ethanol. The juice from the onion CAL 505 cultivar, which contain 8.4 ºBrix soluble solid, was converted by yeast to onion wine containing 3.92% (v/v) ethanol; and then fermented further to onion vinegar with 3.43% (v/v) acetic acid. Evaluations of the fermentation efficiencies for Acetobacter sp. CCRC 12326 on fermenting onion wines (OWs) with different concentrations of ethanol, and OWs with or without supplementing with 1% acetic acid was performed. The highest acidity of onion acidity vinegar in the 6th day was 3.44% (v/v) from the OW containing 5% ethanol, and the highest one in the 8th day was 3.61% from the OW with 7% alcohol. However, supplementing the OW with 1% acetic acid did not enhance the vinegar fermentation rate. The acidity of onion vinegar was 3.48% at day 15 if the fresh OW was added during fermentation, and accompanied by the increase of final volume of broth to 2.25 times. Both acetic acid production rate and acidity increased if a modified two-stage vinegar fermentation method which comprised four operation modes(A1, A2, B1, B2) was used. The highest acetic acid production rate was obtained for the vinegar fermentation performed according to A1 mode (starter-making 3 days, mother vinegar-making 3 days); the concentration of acetic acid was 4.97% after 24 days. However, the final acidity was higher, 6.02%, for that of using B2 mode (starter-making 5 days and mother vinegar-making 5 days). The contents of major organic acids except acetic acid in the onion vinegar were glucuronic acid 0.43, gluconic acid 0.91, tartaric acid 0.16, pyroglutamic acid 0.097, and malic acid 0.80 g/100ml.
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Liao, Pei-Hsiu, and 廖珮秀. "Purification of Phytochelatin Synthase from Fission Yeast (Schizosaccharomyces pombe 806) and Preparation of Its Monospecific Antibody." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/73319243064749556481.
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碩士國立臺灣大學
農業化學研究所
91
The heavy metal sequestration mechanism in a cell was triggered when cadmium was entered from the environment. In fission yeast, C. elegans, and plant, phytochelatin (PC) was synthesized to chelate the cadmium, and produced the Cd-PC complex, which will reduce the damage caused by heavy metals. PC is catalytically synthesized by the enzyme PC synthase (PCS), which is activated by cadmium in the cell. Wu (2000) purified the PCS from fission yeast, and established the purification procedure. Chiu (2001) followed that process, improved the assay protocol, purified the enzyme, and produced the specific antibody against PCS (12F9). Although the activity assay indicated that the purified enzyme was PCS, direct evidence is needed to prove this fact. Especially the gene sequence of PCS from fission yeast was depicted recently (Clemens et al., 1999), and served as an important criteria to verify the above question. This study further improved the purification procedure. Amicon was used to replace gel filtration in desalting, and metal chelating chromatography step was deleted. The monospecific antibody (3H8) was prepared by using a synthetic peptide as the antigen, which was selected from the PCS protein deduced from its genomic sequence. Several protein spots on the two-dimensional electrophoresis gel were stained by the antibodies, and their amino acid sequences were then determined by Edman degradation. Results showed that one of the spot contained part of the PCS sequence.
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Liu, Shujun. "Enzymatic function of active site loop in enolase : preparation and characterization of G37A and G41A mutant yeast enolases." Thesis, 2005. http://spectrum.library.concordia.ca/8723/1/MR14223.pdf.
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Enolase catalyzes the reversible dehydration of 2-phosphoglyceric acid (2-PGA) to phosphoenolpyruvate (PEP) near the end of the glycolytic pathway. During enolase catalysis, three major loops undergo a large position change upon substrate and metal ion binding, especially in the active site loop (Pro35-Ala45). The hinge sites in the active site loop are Gly residues at positions 37 and 41. To gain some information about the function of active site loop movement in catalysis and subunit interactions, the Gly residues at position 37 and 41 in yeast enolase have been mutated to Ala. These observations confirm the active site loop movement is not only essential for correctly positioning Ser39 for coordination of the catalytic metal ion, but also plays some crucial function in maintaining the proper linkage with other loops. In turn, these precise loop conformations are essential in maintaining the correct active site structure and proper subunit interactions
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Citulski, Joel. "The Fate of Net Estrogenicity and Anti-Estrogenicity During Conventional and Advanced Biosolids Treatment Processes." Thesis, 2012. http://hdl.handle.net/10214/3285.
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Biosolids are the nutrient-rich organic residual materials resulting from the treatment of domestic sewage at a wastewater treatment facility, and are increasingly land-applied for agricultural and land-reclamation purposes as part of the wastewater management process. While the presence and fate of estrogenic endocrine-disruptors (eEDCs) in wastewater has been extensively studied, much less focus has been given to examining the presence and fate of eEDCs during biosolids treatment. In particular, little work has been done to measure the net estrogenic potency of biosolids using in vitro bioassays, such as the Yeast Estrogen Screen (YES) assay. This is despite the fact that widespread land-application of biosolids provides for the direct introduction of eEDCs into terrestrial and aquatic environments. The relative scarcity of bioassay-based net estrogenicity data for sludges and biosolids is in large part due to the analytical challenges involved in working with such a complex sample matrix.
Comprehensive sampling at wastewater treatment plants in Guelph and London, ON, demonstrated that the estrogenicity of anaerobically-treated biosolids is considerably lower (12.0-19.7 ng/g estradiol-equivalents) than that reported in earlier published studies. The results of the present study were made possible due to the development of a sample preparation methodology that overcame the toxic effects that sludge and biosolid samples typically exert on yeast cells in the YES assay. An anti-estrogenicity assay was also applied for the first time to sludges/biosolids to measure the extent to which antagonistic compounds ‘block’ the response of the YES assay. The results of these tests suggest that although the net estrogenicity of anaerobically treated solids is indeed low, up to twice the amount of estrogenicity measured by the YES assay may be masked in biosolids by the presence of antagonistic compounds.
While aerobic treatment conditions reduced net estrogenicity to at-or-below detectable levels, net estrogenicity remained relatively constant throughout the unit processes of the anaerobic treatment train. Biosolid ageing during storage led to an overall decrease in net estrogenicity of both conventionally-treated “restricted use” and advanced-treated “unrestricted use” anaerobic biosolids. However, levels of net estrogenicity were observed to spike during the early stages of storage, particularly under freeze/thaw conditions.Natural Science and Engineering Research Council of Canada (NSERC) PGS-D3 scholarship, Water Environment Association of Ontario, Canadian Water Network
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Moremi, Mahlatse Ellias. "The improvement of bioethanol production by pentose fermenting yeasts previously isolated from herbal preparations, dung beetles and marula wine." Thesis, 2020. http://hdl.handle.net/10386/3392.
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Thesis (M.Sc. (Microbiology)) -- University of Limpopo, 2020Production of bioethanol from lignocellulosic biomass has gained significant attention worldwide as an alternative fuel source for the transportation sector without affecting food supply. Efficient conversion of pentose sugars (L-arabinose and D-xylose) produced during hydrolysis of hemicellulose to ethanol can enhance the economic viability. In this study, a total of 390 yeasts isolated from Marula wine, the gut of dung beetles, herbal concoctions and banana residues were screened for the ability to ferment L-arabinose and D-xylose. Fourteen yeasts were able to ferment both pentose sugars and ten strains were subjected to an adaptation process in the presence of acetic acid using L-arabinose as carbon source. Four adapted strains of Meyerozyma caribbica were able to ferment L-arabinose to ethanol and arabitol in the presence of 3 g/L acetic acid at 35 °C. Meyerozyma caribbica Mu 2.2f fermented D-xylose, L-arabinose and a mixture of D-xylose and L-arabinose to produce 1.7, 3.0 and 1.9 g/L ethanol, respectively, compared to the parental strain with 1.5, 1.0 and 1.8 g/L ethanol, respectively, in the absence of acetic acid. The adapted strain of M. caribbica Mu 2.2f produced 3.6 and 0.8 g/L ethanol from L-arabinose and D-xylose, respectively in the presence of acetic acid while the parental strain failed to grow. In the bioreactor, the adapted strain of M. caribbica Mu 2.2f produced 5.7 g/L ethanol in the presence of 3 g/L acetic acid with an ethanol yield and productivity of 0.338 g/g and 0.158 g/L/h, respectively at a KLa value of 3.3 h-1. The adapted strain produced 26.7 g/L arabitol with a yield of 0.900 g/g at a KLa value of 4.9 h-1. Meyerozyma caribbica Mu 2.2f could potentially be used to produce ethanol and arabitol under stressed conditions.
National Research Foundation (NRF)
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Brummer, Mieke. "The effect of yeast cell wall preparations on salmonella colonisation, gastrointestinal health and performance of broiler chickens." Diss., 2007. http://hdl.handle.net/2263/24047.
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The main aim of the studies was to evaluate the modes of actions of Bio-Mos and the effect that it has on intestinal health as well as performance in broiler chickens. For the purpose of this study there were 2 main objectives. The first was to determine the effect of Bio-Mos as well as soluble mannan on salmonella colonization and to do this it was necessary to develop an in vivo pathogen challenge model, specifically designed for salmonella, using the chicken as animal model. The aim with this salmonella assay was to design a model that could accurately determine the efficacy of different components of the yeast cell wall at reducing or eliminating salmonella colonisation in chickens. The second objective was to evaluate the effect of Bio-Mos with or without the addition of a soluble mannan, fed at different inclusion levels, on chicken health. Specific parameters measured included feed conversion ratios (FCR), volatile fatty acid (VFA) analysis, antibiotic resistance amongst coliform populations, immunoglobulin quantification and gut morphology. Gut morphology measurements included villi height and width, crypt depth, muscularis thickness, goblet cell size and goblet cell density. The salmonella assay trial was not able to yield positive results for either the cell wall preparations or the positive control, indicating that there are some external factors that have to be addressed before this assay can be used to draw any accurate conclusions from. The second section of this study did show FCR differences between some of the treatments, but did not show numerically large differences for VFA production or antibiotic resistance, however the histological evaluation did yield interesting results. Measurements based on the villi height and width, crypt depth and muscularis thickness showed no significant differences between treatments but there was a treatment effect on the goblet cells. The goblet cells of chickens receiving cell wall preparations were statistically significantly larger and present at a higher density than those of the control treatment birds. In an attempt to develop the salmonella assay several aspects of the existing assay model were altered or eliminated. It is possible that the assay can work with some more adjustments, but due to time constrictions it was not possible to further explore alternative approaches. Little research has been done on the effect of nutrition on the goblet cells in chicken intestines. The results noted in this report warrant a more in-depth investigation into the exact modes of action resulting in the differences in goblet cells observed. The use of cell wall preparations on a commercial level holds many advantages, as cell wall preparations appear to affect animal health in a positive way.Dissertation (MSc (Agric) : Animal Nutrition)--University of Pretoria, 2008.
Animal and Wildlife Sciences
MSc (Agric)
unrestricted
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Silva, Sara Maria Cunha Oliveira. "Estudo das curvas de inactivação térmica de leveduras em diferentes matrizes de fruta." Master's thesis, 2018. http://hdl.handle.net/10400.14/28652.
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Com base no histórico interno da Frulact, duas leveduras (Pichia anomala e Candida intermedia) e diferentes matérias-primas, nomeadamente, coco, ananás, manga, framboesa, morango e amora, foram selecionadas com o intuito de (i) caracterizar e monitorizar a carga microbiana (ii) avaliar o comportamento das leveduras em estudo quando submetidas a diferentes binómios tempo/temperatura, nomeadamente 50, 60 e 70 °C durante 5, 15, 30, 45, 60, 90 e 120 segundos, (iii) identificar a relação de ácidos orgânicos e açúcares presentes nas matrizes de fruta e o comportamento das leveduras em estudo sujeitas a diferentes temperaturas, (iv) quantificar o desenvolvimento microbiano em iogurtes quando dosificados com preparados de fruta selecionados.
Os resultados mostraram que a carga microbiana nos frutos vermelhos foi superior à verificada em frutos tropicais (p > 0,05). A levedura C. intermedia foi mais sensível ao perfil de temperaturas testado do que P. anomala (p < 0,05). Não existiu uma correlação entre a inativação das diferentes leveduras quando inoculadas nos vários preparados e os parâmetros avaliados neste estudo, nomeadamente, pH, perfil de ácidos orgânicos e açúcares e atividade da água (p > 0,05). Concentrações mais elevadas de ácidos orgânicos e açúcares, não conferiram resistência cruzada às diferentes temperaturas (p > 0,05). Iogurtes açucarados constituíram uma matriz mais propícia ao desenvolvimento microbiano, uma vez que P. anomala é capaz de fermentar diferentes açúcares tais como a lactose, sacarose e galactose (p > 0,05). A nível sensorial observaram-se alterações nos parâmetros de aceitação dos diferentes iogurtes durante o armazenamento a 4 °C durante 31 dias.Given Frulact's internal records, two particular yeasts (Pichia anomala and Candida intermedia) as well as several raw materials such as coconut, pineapple, mango, raspberry, strawberry and blueberry were selected with a set goal of (i) characterize and monitor it's microbial load, (ii) assess the yeasts' behaviour when subjected to different time/temperature binomials, namely 50, 60 and 70 °C during 5, 15, 30, 45, 60, 90 e 120 seconds, (iii) correlating organic acids and respective sugars present within each fruit matrices as well as evaluate the yeasts' behaviour, according to these parameters, when subjected to different temperatures, (iv) quantify the microbial development in yogurts when dosed with fruit-based preparations. The results showed that the microbial load in red berries is greater than when studied in tropical fruits (p > 0.05). The yeast C. intermedia was more sensitive to the profile of temperatures chosen than its counterpart, P. anomala (p < 0.05). There wasn’t a correlation between the inactivation of the yeasts when inoculated with the fruit-based preparations and the various parameters in which it was studied, namely: pH, the organic acids and sugars profile and water activity (p > 0.05). Higher concentrations of organic acids and sugars do not boost their cross-resistance to temperature (p > 0.05). Yogurts with sugar additions showed a more favourable environment for microbial development, given that P. anomala has the capability of fermenting several sugars such as lactose, sucrose and galactose (p > 0.05). Regarding sensory analysis, changes in the acceptance parameters of the different yogurts were observed during storage at 4 °C for 31 days.