Microbial community structure of ethanol type fermentation in bio‐hydrogen production

Ren, Nanqi; Xing, Defeng; Rittmann, Bruce E.; Zhao, Lihua; Xie, Tao; Zhao, Xin

doi:10.1111/j.1462-2920.2006.01234.x

Cited by 203 publications

(137 citation statements)

References 53 publications

(53 reference statements)

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“…Moreover, members of the genus Clostridium are originally metabolically versatile. Previous studies have shown that isolated Clostridium species are able to utilize various substrates, ranging from those with a high molecular weight and a complex structure (Lynd et al, 2002;Murashima et al, 2002) to those with a low molecular weight and a simple structure (Ren et al, 2006;Seedorf et al, 2008). For example, Clostridium acetireducens sp.…”

Section: Discussionmentioning

confidence: 99%

Novel Clostridium populations involved in the anaerobic degradation of Microcystis blooms

et al. 2010

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Understanding the microbial degradation of Microcystis biomass is crucial for determining the ecological consequences of Microcystis blooms in freshwater lakes. The purpose of this study was to identify bacteria involved in the anaerobic degradation of Microcystis blooms. Microcystis scum was anaerobically incubated for 90 days at three temperatures (15 1C, 25 1C and 35 1C). We used terminal restriction fragment length polymorphism (T-RFLP) analysis of bacterial 16S rRNA genes, followed by cloning and sequencing of selected samples, to reveal the community composition of bacteria and their dynamics during decomposition. Clostridium spp. were found to be the most dominant bacteria in the incubations, accounting for 72% of the sequenced clones. Eight new clusters or subclusters (designated CLOS.1-8) were identified in the Clostridium phylogenetic tree. The bacterial populations displayed distinct successions during Microcystis decomposition. Temperature had a strong effect on the dynamics of the bacterial populations. At 15 1C, the initial dominance of a 207-bp T-RF (Betaproteobacteria) was largely substituted by a 227-bp T-RF (Clostridium, new cluster CLOS.2) at 30 days. In contrast, at 25 1C and 35 1C, we observed an alternating succession of the 227-bp T-RF and a 231-bp T-RF (Clostridium, new cluster CLOS.1) that occurred more than four times; no one species dominated the flora for the entire experiment. Our study shows that novel Clostridium clusters and their diverse consortiums dominate the bacterial communities during anaerobic degradation of Microcystis, suggesting that these microbes' function in the degradation process.

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Section: Discussionmentioning

confidence: 99%

Novel Clostridium populations involved in the anaerobic degradation of Microcystis blooms

et al. 2010

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“…The extracted DNA was used as the template for PCR amplification of the 16S rRNA gene. The 16S rRNA gene was amplified with a pair of universal primers: BSF8/20, 5Ј-AGAGTTTGATCCTGGCTCAG-3Ј, and PLA, 5Ј-GGTACTTAGATGTTTCAGTTC-3Ј (Invitrogen, Co., Ltd., Shanghai, China) (49). The reaction mixture (50 l) contained 10ϫ PCR buffer, 10 mmol/liter Tris-HCl, 0.2 mmol/liter deoxynucleoside triphosphate (dNTP), 2.5 U of Taq DNA polymerase, 0.5 mol/liter forward primer and 0.5 mol/liter reverse primer, and 20 ng template DNA.…”

Section: Methodsmentioning

confidence: 99%

Isolation and Characterization of Shigella flexneri G3, Capable of Effective Cellulosic Saccharification under Mesophilic Conditions

Wang

Gao

Ren

et al. 2011

Appl Environ Microbiol

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A novel Shigella strain (Shigella flexneri G3) showing high cellulolytic activity under mesophilic, anaerobic conditions was isolated and characterized. The bacterium is Gram negative, short rod shaped, and nonmotile and displays effective production of glucose, cellobiose, and other oligosaccharides from cellulose (Avicel PH-101) under optimal conditions (40°C and pH 6.5). Approximately 75% of the cellulose was hydrolyzed in modified ATCC 1191 medium containing 0.3% cellulose, and the oligosaccharide production yield and specific production rate reached 375 mg g Avicel ؊1 and 6.25 mg g Avicel ؊1 h ؊1 , respectively, after a 60-hour incubation. To our knowledge, this represents the highest oligosaccharide yield and specific rate from cellulose for mesophilic bacterial monocultures reported so far. The results demonstrate that S. flexneri G3 is capable of rapid conversion of cellulose to oligosaccharides, with potential biofuel applications under mesophilic conditions.Lignocellulosic biomass is abundant in nature, as well as in agricultural, forestry, and municipal wastes, and can be used as an excellent bioconversion feedstock. Biomass-derived saccharides, such as glucose, cellobiose, and other minor sugars, can be readily fermented by appropriate microbes into bioenergy products, such as hydrogen, ethanol, biodiesel, and other commodity chemicals. However, the high cost of converting biomass to sugars is the primary factor impeding establishment of a cellulosic-biofuels industry (24, 40). Lignocellulosic biofuels can be competitive on an industrial scale if efficient technologies can be developed (29,39). Currently, the most efficient process for utilization of cellulose as a feed stock is either a three-step process (separate hydrolysis and fermentation [SHF]) involving separate pretreatment, cellulose hydrolysis (i.e., saccharification), and hexose and pentose fermentation steps or a two-step process (simultaneous saccharification and fermentation [SSF]) involving separate pretreatment and simultaneous saccharification of hexose and pentose fermentation (48, 64). Combining hydrolysis of cellulose with simultaneous fermentation of hexose and pentose in a single process, i.e., direct microbial conversion (DMC), is an ideal strategy for converting cellulosic biomass to ethanol. However, no single microorganism/community can implement DMC with high efficiency (67). In any of these configurations, rapid and efficient saccharification is critical for developing competitive biotechnologies for cellulosic-biofuel production.In nature, cellulose is hydrolyzed to oligosaccharides by microorganisms, mainly fungi (e.g., brown-, white-, and soft-rot fungi) and bacteria (e.g., Clostridium and Cellulomonas), which produce either free cellulolytic enzymes or extracellular enzyme complexes known as cellulosomes (12). Many white-rot Basidiomycetes and some Actinomycetes have been employed for hydrolyzing lignocellulosic materials. For example, Trichoderma reesei has shown the highest cellulolytic activity currently known (27)....

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“…and Enterobacter dominance. [68] The efficiency of biohydrogen production process is different depending on pretreatment method, dominance bacteria, substrate, and metabolic pathway. [910] With understanding metabolic pathway, the calculation of theoretical hydrogen yield is possible.…”

Section: Introductionmentioning

confidence: 99%

“…[212] Acetate-propionate pathway is another fermentation pathway that does not produce any hydrogen. [8]…”

Section: Introductionmentioning

confidence: 99%

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Comparison of acetate-butyrate and acetate-ethanol metabolic pathway in biohydrogen production

et al. 2018

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Background:Hydrogen gas is the cleanest energy carrier and could be produced by biological process. Dark fermentation is one of the biohydrogen production methods that carried out just on organic wastes conversion.Methods:In this study, the batch tests were conducted to compare the biohydrogen production and glucose fermentation via acetate-butyrate and acetate-ethanol metabolic pathway induced by NaOH and KOH (10 M) pretreatment. In batch test, the glucose concentration in the feed was varied from 3.75 to 15 g/L under mesophilic conditions (37°C ± 1°C). In order to sludge pretreatment, NaOH and KOH (as an alkaline agent) was used.Results:Batch tests showed that maximum biohydrogen production under NaOH (2.7 ± 0.5 L) and KOH (2.2 ± 0.7 L) pretreatment was achieved at 15 g/L of influent glucose. In the batch test, with increasing influent glucose concentration, the lower yields of hydrogen were observed. The biohydrogen reactions had good electron closure (5.2%–13.5%) for various glucose concentrations and pretreatments. For NaOH and KOH pretreatment, the biohydrogen yield decreased from 2.49 to 1.63 and from 2.22 to 1.2 mol H2/mol glucose, respectively, when glucose concentration increased from 3.75 to 15 g/L.Conclusions:By applying alkaline sludge pretreatment by NaOH and KOH, the glucose fermentation was followed with acetate-butyrate and acetate-ethanol metabolic pathway, respectively. The lower biohydrogen yields were observed under acetate-ethanol metabolic pathway and related to metabolically unfavorable for biohydrogen production.

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Microbial community structure of ethanol type fermentation in bio‐hydrogen production

Cited by 203 publications

References 53 publications

Novel Clostridium populations involved in the anaerobic degradation of Microcystis blooms

Novel Clostridium populations involved in the anaerobic degradation of Microcystis blooms

Isolation and Characterization of Shigella flexneri G3, Capable of Effective Cellulosic Saccharification under Mesophilic Conditions

Comparison of acetate-butyrate and acetate-ethanol metabolic pathway in biohydrogen production

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