Academic literature on the topic 'Purple non-sulfur photosynthetic bacteria'

For the purpose of sulphide removal in aquaculture ponds, three strains (name: TH21, QN71, QN51) were isolated and selected with the highest sulphide removal activity from Thanh Hoa and Quang Ninh coastal zones. These strains have identified and tested in a number of aquaculture ponds in different areas with good water quality results. With the objective of purple non sulfur bacteria biomass production containing 3 selected strains for wide application and suitable price for farmers, in this study, we study on optimum conditions of mixed purple non sulfur bacteria biomass production at pilot scale. The results showed that the sources of substrates were soybean meal (1g/l) and acetate (0.5g/l). These substrates are low cost, easy to find, convenient in large culture. The mixture of photosynthetic bacteria can be cultured in glass tanks, under micro aerobic and natural lighting conditions that produce highly concentrated photosynthetic bacteria and lowest rest media.<br>Nhằm mục tiêu xử lý sulphide trong môi trường nuôi trồng thủy sản, chúng tôi đã phân lập và lựa chọn được ba chủng vi khuẩn tía quang hợp có khả năng loại bỏ sulphide cao nhất ký hiệu TH21, QN71, QN52 từ các vùng ven biển Thanh Hóa và Quảng Ninh. Các chủng này đã được định loại và thử nghiệm tại một số ao nuôi thủy sản ở các vùng khác nhau thu được kết quả tốt về chất lượng nước. Để tạo chế phẩm vi khuẩn tía quang hợp từ 3 chủng lựa chọn được ứng dụng rộng rãi và có giá thành phù hợp cho nông hộ, trong nghiên cứu này, chúng tôi nghiên cứu tối ưu hóa các điều kiện sản xuất sinh khối hỗn hợp 3 chủng vi khuẩn tía quang hợp ở quy mô pilot. Kết quả cho thấy đã tìm kiếm được nguồn cơ chất là bột đậu tương (1g/l) và acetate (0.5g/l) là những chất có giá thành thấp, dễ tìm kiếm, thuận tiện trong nhân nuôi ở quy mô lớn. Hỗn hợp vi khuẩn tía quang hợp có thể nuôi trong các bể kính, ở điều kiện vi hiếu khí, có ánh sáng chiếu tự nhiên có thể sản xuất được chế phẩm vi khuẩn tía quang hợp có mật độ cao, cơ chất còn lại sau sản xuất là ít nhất.

Mercury (Hg) is a global pollutant and potent neurotoxin that bioaccumulates in aquatic and terrestrial food webs as monomethylmercury (MeHg). Anaerobic microbes are largely responsible for MeHg production, which depends on the bioavailability of inorganic Hg substrates to methylators. Hg redox cycling pathways such as Hg reduction play a key role in determining Hg’s availability in the environment. Although abiotic photochemical Hg reduction typically dominates in oxic surface environments, Hg reduction pathways mediated by photosynthetic and anaerobic microbes are thought to play an important role in anoxic habitats where light is limited and MeHg production occurs. Currently, the physiological mechanisms driving phototrophic and anaerobic Hg reduction remain poorly understood. The main objective of my thesis is to provide mechanistic details on novel anaerobic and phototrophic Hg reduction pathways. I used a combination of physiological, biochemical and trace Hg analytical techniques to study Hg reduction pathways in a variety of anaerobic and photosynthetic bacteria. I demonstrated that Hg redox cycling was directly coupled to anoxygenic photosynthesis in aquatic purple non-sulphur bacteria that reduced HgII when cells incurred a redox imbalance. I discovered that terrestrial fermentative bacteria reduced Hg through pathways that relied on the generation of reduced redox cofactors. I also showed that sulphur assimilation controlled Hg reduction in an anoxygenic phototroph isolated from a rice paddy. In addition, I developed methods to explore cryptic anaerobic Hg redox cycling pathways using Hg stable isotope fractionation. At its core, my thesis underscores the intimate relationship between cell redox state and microbial Hg reduction and suggests a wide diversity of microbes can participate in anaerobic Hg redox cycling.

The movement towards a more sustainable energy economy may require not only the generation of cleaner fuel sources, but the conversion of waste streams into value-added products. Phototrophic purple non-sulfur bacteria are capable of metabolizing VFAs (volatile fatty acids)and generate hydrogen as a byproduct of nitrogen fixation using energy absorbed from light. VFAs are easily produced from dark anaerobic fermentation of food, agricultural, and municipal wastes, which could then be fed into photobioreactors of purple bacteria for hydrogen production. The process of photofermentation by purple bacteria for hydrogen production remains attractive due to the capability of reaching high substrate conversions under mild operating conditions, but increasing the efficiency of converting light energy into hydrogen remains challenging. Purple bacteria cannot utilize the entire solar spectrum, and the dominant region of absorption lies in the near-infrared region above 800 nm. In this work, the model purple non-sulfur bacteria Rhodopseudomonas palustris was used to study different strategies to increase light utilization and hydrogen production. Near-infrared LED arrays were selected to match the target bacteriochlorophyll absorption range, and were tested to be used as a sole illumination source for photofermentation. Additionally, plasmonic nanoparticles with resonant frequencies matching bacterial absorbance were added in solution to increase light utilization through scattering and near field electric enhancement effects at intensities around 100 W/m2 . Both of these approaches proved to increase cellular growth rate and hydrogen production, which opens the door to utilizing more advanced photonic structures for use in bacterial phototrophic processes.

Biological hydrogen production is a renewable, carbon-neutral and clean route for hydrogen production. Purple non-sulfur (PNS) bacteria have the ability to produce biohydrogen via photofermentation process. The type of the bacterial strain used in photofermentation is known to have an important effect on hydrogen yield. In this study, the effect of different co-cultures of PNS bacteria on photofermentation process was investigated in search of improving the hydrogen yield. For this purpose, growth, hydrogen production and substrate utilization of single and co-cultures of different PNS bacteria (R. capsulatus (DSM 1710), R. capsulatus hup- v (YO3), R. palustris (DSM 127) and R. sphaeroides O.U.001 (DSM 5864)) were compared on artificial H2 production medium in 150 mL photobioreactors under continuous illumination and anaerobic conditions. In general, higher hydrogen yields were obtained via co-cultivation of two different PNS bacteria when compared with single cultures. Further increase in hydrogen yield was observed with co-cultivation of three different PNS bacteria. Co-cultures of two different PNS bacteria have resulted in up to 1.4 and 2.1 fold increase in hydrogen yield and hydrogen productivity. Whereas co-cultures of three different PNS bacteria have resulted in up to 1.6 and 2.0 fold increase in hydrogen yield and hydrogen productivity compared to single cultures. These results indicate that, defined co-cultures of PNS bacteria produce hydrogen at a higher yield and productivity, due most probably to some synergistic relationship. Further studies regarding the physiological and molecular changes need to be carried out for deeper understanding of the mechanism of hydrogen production in co-cultures.

Some purple bacteria species, such as Rhodopseudomonas palustris 2.1.6, produce light harvesting antenna (LH2) with unusual absorption spectra when they are grown under low-light intensities. This ability is often related to the presence of multiple genes encoding the LH2 apoproteins. This thesis describes isolation of pure stable LH2s from Rhodopseudomonas palustris 2.1.6 grown at different light intensities, determination of the polypeptide composition of high- (HL) and low-light (LL) LH2 complexes and characterisation their spectroscopic properties using various optical spectroscopies. The question of whether rings with a heterogeneous apoprotein composition exist has been addressed by single-molecule spectroscopy. For the first time, direct evidence that individual LL LH2 complexes have a heterogeneous αβ-apoprotein composition has been found. Such mixed rings feature Bchl a molecules with both B820-like and B850-like site-energies. This finding was supported by a femtosecond study on the energy transfer reactions and exciton relaxations within both HL and LL LH2 complexes. This thesis also describes attempts to crystallise the HL and LL LH2s. Even though three-dimensional crystals of both HL and LL LH2 complexes only diffracted to low resolution, it was possible to use molecular replacement to obtain structures that suggest both these types of LH2s are nonamers.

As necessidades de energia global são, na sua maioria, dependentes de combustíveis fósseis. Hidrogênio é uma energia limpa alternativa a esses combustíveis fósseis. Bactérias fototróficas produzem hidrogênio a partir de compostos orgânicos por meio de processo anaeróbio dependente de luz. Assim, este trabalho visou avaliar o efeito das concentrações iniciais de ácido acético e biomassa, e a influência da intensidade luminosa, na produção de hidrogênio por bactéria fototrófica púrpura não-sulfurosa. Foram utilizados reatores em batelada de 2000 mL, com volume útil de 1000 mL e headspace de 1000 mL preenchido com hélio. Nos reatores foi adicionado ácido acético e glutamato de sódio (0,8 mmol/L) como fontes de carbono e nitrogênio, respectivamente, e cultura de bactéria fototrófica púrpura não-sulfurosa previamente purificada. O aumento da concentração inicial de ácido acético de 10 mmol/L para 17 mmol/L não promoveu mudanças significativas tanto no crescimento celular, quanto, na produção de hidrogênio (8,3 mL \'H IND.2\'/g massa seca.h e 8,8 mL \'H IND.2\'/g massa seca.h, respectivamente), para intensidade luminosa de 9000 - 10.000 lux. Nessa mesma intensidade luminosa, o aumento da concentração de biomassa inicial de 0,02 g/L para 0,04 g/L favoreceu o aumento da produção de hidrogênio de 8,8 mL \'H IND.2\'/g massa seca.h para 10,6 mL \'H IND.2\'/g massa seca.h, respectivamente. A produção de hidrogênio diminuiu acentuadamente de 10,6 mL \'H IND.2\'/g massa seca.h para 1,0 mL \'H IND.2\'/g massa seca.h com a diminuição da intensidade luminosa de 9000 - 10.000 lux para 4000 - 5000 lux. Na ausência de luz não ocorreu crescimento e produção de hidrogênio. A cultura manteve-se predominantemente avermelhada e as análise microscópicas mostraram a predominância de bacilos curvos, gram-negativos, aglomerados em formações de roseta; características típicas de alguns gêneros de bactérias fototróficas púrpuras não-sulfurosas. Todos os ensaios foram realizados à temperatura de 30 \'+ OU -\' 1 grau Celsius. A análise da estrutura da comunidade microbiana foi realizada por reação de polimerização em cadeia (PCR) de fragmentos de gene RNAr 16S, seguida de eletroforese em gel de gradiente desnaturante (DGGE), e revelou que não houve variações relevantes na estrutura das populações microbianas em função das diferentes condições de cultivo.<br>The global energy requirements are mostly dependent on fossil fuels. Hydrogen is a clean energy alternative to these fuels. Phototrophic bacteria produce hydrogen from organic compounds by an anaerobic light-dependent electron transfer process. Therefore, this study aimed at to evaluate the effect of the initial concentrations of acetic acid and biomass, and the influence of the light intensity on hydrogen production by purple non-sulfur phototrophic bacteria. The experiments were performed in batch operation, in reactors of 2000 mL, with culture volume of 1000 mL and headspace of 1000 mL, filled with helium. Acetic acid and sodium glutamate (0.8 mmol/L) were used as sources of carbon and nitrogen, respectively, and culture of purple non-sulfur phototrophic bacteria previously purifided. The increase of the initial acetic acid concentration from 10 mmol/L to 17 mmol/L did not promote significant changes in the cell growth and in the hydrogen production (8.3 mL \'H IND.2\'/g dry weight.h and 8.8 mL \'H IND.2\'/g dry weight.h, respectively), under a light intensity of 9000 - 10,000 lux. In this same light intensity, the increase of the initial biomass concentration from 0.02 g/L to 0.04 g/L resulted in an increase in the hydrogen production from 8.8 mL \'H IND.2\'/g dry weight.h to 10.6 mL \'H IND.2\'/g dry weight.h, respectively. The hydrogen production suddenly decreased from 10.6 mL \'H IND.2\'/g dry weigh.h to 1.0 mL \'H IND.2\'/g dry weight.h with the reduction of the light intensity from 9000 - 10,000 lux to 4000 - 5000 lux. Hydrogen production was not observed in absence of light. The culture remained predominantly purple and the microscopic analysis showed the predominance of rod-shaped cells, gram-negative, accumulated in formation of rosettes; typical characteristics of some types of purple non-sulfur phototrophic bacteria. The analysis of the structure of the microbial community was carried out by reaction of polymerization in chain (PCR) of the RNAr 16S, followed of denaturing gradient gel electrophoresis (DGGE), and reveled that the structure of the microbial populations did not change significantly in function of the different conditions of culture.

O objetivo deste trabalho foi enriquecer consórcio microbiano a partir de mistura de lodo granular de digestor anaeróbio de fluxo ascendente sob condições fototróficas anoxigênicas. Por meio de técnica de biologia molecular foi possível identificar 17 unidades taxonômicas operacionais (UTO) no consórcio microbiano, dentre as quais seqüências similares a Rhodobacter, gênero amplamente citado nos estudos de produção de gás hidrogênio por bactérias fototróficas. Exames microscópicos do consórcio fototrófico indicaram predomínio de bacilos Gram-negativos. Ensaios sob condições fototróficas foram realizados com dois meios de cultivo (RCVB e FANG) e os seguintes substratos orgânicos: ácido acético, butírico, cítrico, lático e málico, empregados como fonte de carbono, tanto para o crescimento celular, como para a produção do gás hidrogênio. A relação C/N inicial foi 30/4 e posteriormente 15/2, com o objetivo de favorecer o crescimento celular e a produção do \'H IND.2\'. A concentração dos substratos foi determinada de forma com que essa relação se mantivesse a mesma. O crescimento celular e consumo dos ácidos orgânicos foram similares para os dois meios de cultivo empregados. Entretanto, a produção do gás hidrogênio foi maior nos ensaios com o meio FANG. Dentre os substratos utilizados o consumo dos ácidos cítrico e málico foram os maiores (~100%), para concentrações iniciais de 3,3 g/L e 2,6 g/L, respectivamente. O menor consumo 25% foi observado em meio RCVB e ácido acético (2,5 g/L). O crescimento da biomassa variou de 0,06 g/L a 1,1 g/L, enquanto que a velocidade máxima específica de crescimento variou de 0,4 a 0,2 g SSV/L.d entre os substratos utilizados. A menor e maior concentração de hidrogênio foram de 8,5 e 22 mmol \'H IND.2\'/L, para os reatores alimentados com ácido lático e málico em meio FANG, respectivamente. Pôde-se concluir que o consórcio fototrófico enriquecido foi capaz de utilizar os ácidos orgânicos para produção do gás hidrogênio.<br>The aim of this work was enrich a mixture of granular sludge of an up flow anaerobic sludge blanket (UASB) under anoxygenic phototrophic conditions. The techniques of molecular biology identified 17 operational taxonomic units (UTO) in the microbial consortium among the sequences analised, which were similar to Rhodobacter, genus widely cited in studies of hydrogen gas production by phototrophic bacteria. Microscopic examinations of the phototrophic consortium showed predominance of Gram-negative bacilli. Tests were conducted under phototrophic conditions with two culture media (RCVB and FANG) and the following organic substrates: acetic, butyric, citric, lactic and malic acids that were used as carbon source for both cell growth and for the hydrogen gas production. The carbon nitrogen ratio (C/N) in the preliminaries tests was 30/4 and then it was changed to15/2 in order to improve the cell growth and hydrogen production. The concentration of substrates was determined for remain the same carbon/nitrogen ratio among the substrates. The cell growth and consumption of organic acids were similar for the two culture media used. However, the production of hydrogen gas was higher in trials with the medium FANG. Among the substrates used, the consumption of malic and citric acids were the highest (~100%) for initial concentrations of 3.3 g/L and 2.6 g/L, respectively. The shortest consumption (25%) was observed for the cells that grew on acetic acid, 2.5 g/L in RCVB culture medium. The growth of the biomass varied from 0.06 g/L to 1.1 g/L, whereas the maximum specific growth rate ranged from 0.4 to 0.2 g VSS/L.d between the substrates used. The lowest and highest concentrations of hydrogen were 8.5 and 22 mmol \'H IND.2\'/L for the reactor fed with lactic acid and malic acid in FANG\'s medium, respectively. It was concluded that the phototrophic consortium was able to use those organic acids for the production of hydrogen gas.

碩士<br>元智大學<br>生物科技與工程研究所<br>99<br>Purple non-sulfur bacteria (PNSB) possess diverse metabolic pathway to survive in different environments, including photoautotrophic, photoheterotrophic, chemoautotrophic as well as chemoheterotrophic metabolisms. PNSB have been widely used in the fields of environmental protection, agricultural production, aquaculture and medical application, etc. The unique physiological characteristics of PNSB have also attracted the attention of researchers to investigate the possible application of these microorganisms. In this study, we have isolated and identified several strains of photosynthetic bacteria from sediments or soil from different environment in northern Taiwan, including pond water, rice field and channel. Enrichment technology was employed for isolation of PNSB with anaerobic incubation under light condition. The isolates were identified by 16S rRNA gene sequence analysis and several strains of Rhodobacter sp. were chosen for further evaluation for their applications such as production of coenzyme Q10 and bacterial pigments.

碩士<br>國立中興大學<br>環境工程學系所<br>105<br>Conversions of organic substrates to biohydrogen through separated dark-fermentation or photo- fermentation are both being recognized as promising clean energy production techniques. With or without illumination, both fermentations could produce hydrogen gas under anaerobic condition. Therefore, it is possible to enforce dark- and photo-fermentations to occur in the same reactor and it might have advantages over separated fermentation by reducing overall reactor volume since hydrogen-producing PNSB (Photosynthetic purple non-sulfur bacteria) could directly utilize the VFAs formed by dark fermentation. With this motivation, experiments of separated fermentation mode were established. CH5 is a strain of dark-fermentation bacteria (DFB), Clostridium pasteurianum, was found to have optimally cumulative amount of hydrogen when fed with 15 g L-1 glucose and it also produced significant amount of butyrate and acetic. Selecting two PNSB were C6 and G11, Rhodopseudomonas palustris, utilize not only butyrate but also acetate for bio-hydrogen. In the same time, when butyrate was used as sole carbon source, the two isolated PNSB strains could successfully produce 208.8 and 183.1 mL H2 L-1 culture (1 g/L butyric acid), its hydrogen yield were 0.82 and 0.98 mol H2 mol-1 butyrate, respectively. The growth status of hydrogen-producing microorganism in the time of combination was still not clearly explored. In this study, the stable growth period and the logarithmic growth phase of the strain were selected respectively. The anaerobic bioreactor were incubated at 30°C, at 120 rpm on an incubating shaker under 6-7 klux of light illumination using LED lamps. The inoculate at DFB/PNSB ratio were 1:1 (v/v) in co-culture medium (15 g/L glucose). There are maximum hydrogen yield 2.54 and 1.74 mol H2 mol-1 glucose were obtained by log phase of CH5+C6 and CH5+G11, respectively. Stationary phase of CH5+C6 yield maximum accumulative hydrogen production of 1485 mL H2 L-1 culture. C6 is better than G11 go further co-culture with CH5 by shelter of bioreactor experiment. Log phase test has the higher hydrogen yield, after culture 60 hours gas performance was approaching flat. Stationary phase test has the highest accumulative hydrogen production, it could continue to produce gas for 100 hours. For acquisition more accumulative hydrogen production, stationary phase of CH5+C6 got on subsequent study. In order to investigate the effect of light on co-culture fermentation, the shelter of bioreactor by differ cover area in this study. Through differ bioreactor cover area look forward to creating different environment for bacteria co-fermentation. 0% shelter of CH5 has 26% less accumulative hydrogen production than 100% shelter of CH5, it need more study and test to provide whether light supply can change the metabolism of CH5. 100% shelter of C6 has 55% less accumulative hydrogen production and use up more 4.56 g L-1 glucose than 0% shelter of C6. The 69% of gas composition was carbon dioxide, but only 16% was hydrogen produced by 100% shelter of C6. It speculated the 100% shelter of C6 that without light offering energy to promote electronic chain on membrane of PNSB, there are no enough ATP for cell growth not to mention for bio-hydrogen produced. 50% shelter of CH5+C6 promoted 67% accumulative hydrogen production than 0% shelter of CH5+C6, it also upgraded 588% accumulative hydrogen production than 100% shelter of CH5+C6. It could remove 60% glucose in 50% shelter of CH5+C6 and 100% shelter of CH5+C6. Main gas composition in 0% shelter of CH5+C6 and 50% shelter of CH5+C6 were hydrogen, in 100% shelter of CH5+C6 was carbondioxide. It is success for shelter of bioreactor to promote bio-hydrogen of co-culture fermentation. The 50% shelter of CH5+C6 consumed 26% sCOD, the accumulative hydrogen production of 1581 mL H2 L-1 culture, and the hydrogen yield was 1.309 mol H2 mol-1 glucose.