End products and molar growth yield of Clostridium fallax isolated from an anaerobic digester

Ueki, Atsuko; Ueki, Katsuji; Tanaka, Kotone; Takahashi, Ryoko; Takano, Tetsuo

doi:10.1016/0922-338x(91)90163-b

Cited by 8 publications

(2 citation statements)

References 14 publications

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“…Jones and Woods (1986) reported VFA were the main products for the acidification of low-strength wastewaters, but butanol was for high-strength wastewaters. Many acidogenes, such as Clostridium acetobutylicum (Bahl et al, 1982), Clostridium butyricum (Andel et al, 1985), Clostridium cellobioparum (Chung, 1976), Clostridium fallax (Ueki et al, 1991), and Clostridium pasteurianum (Dabrock et al, 1992), and mixed acidogenic cultures (Fang and Yu, 2001), produce hydrogen, acetate, butyrate at low substrate concentrations and shift the metabolic pathways when the substrate concentration exceeds certain thresholds to produce butanol, and in some cases, acetone. In this study, acetone was not detected.…”

Section: Discussionmentioning

confidence: 99%

Thermodynamic analysis of product formation in mesophilic acidogenesis of lactose

Fang

2004

Biotech & Bioengineering

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Thermodynamic analysis on the acidogenesis of lactose was performed to evaluate the different acidogenic patterns and mechanisms by using Gibbs free energy calculation. Batch acidogenesis of lactose was investigated by using an enriched culture at 37 degrees C, pH 5.5 and varied substrate levels. In addition to usual acidogenic products, i-butyrate, valerate, i-valerate, caproate, and propanol were also produced at a significant level. Thermodynamic analysis shows that valerate might be formed through the reaction requiring hydrogen as electron donor and consuming of propionate and carbon dioxide. Caproate was most likely produced directly from butyrate, hydrogen, and carbon dioxide. The minimum amount of Gibbs free energies needed to sustain isomerization of butyrate and valerate were approximately 5.7-5.8 and 4.5-4.6 kJ/mol, respectively. Propanol was produced from acetate, hydrogen, and carbon dioxide with a minimum amount of Gibbs free energy of 41.8-42.0 kJ/mol. Formation of butanol was controlled more by substrate level or population dynamics than by thermodynamics.

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Section: Discussionmentioning

confidence: 99%

Thermodynamic analysis of product formation in mesophilic acidogenesis of lactose

Fang

2004

Biotech & Bioengineering

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“…The efficiency of a hydrogen-producing bioprocess depends highly upon optimal control of factors such as the ratio of substrate concentration to biomass concentration. This ratio significantly influences the metabolic and kinetic characteristics of microorganisms (Chudoba et al, 1992;Lui, 1996;Ueki et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Biohydrogen generation by mesophilic anaerobic fermentation of microcrystalline cellulose

Lay

2001

Biotech & Bioengineering

259

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Sixteen batch experiments were performed to evaluate the stability, kinetics, and metabolic paths of heat-shocked digester (HSD) sludge that transforms microcrystalline cellulose into hydrogen. Highly reproducible kinetic and metabolic data confirmed that HSD sludge could stably convert microcrystalline cellulose to hydrogen and volatile fatty acids (VFA) and induce metabolic shift to produce alcohols. We concluded that clostridia predominated the hydrogen-producing bacteria in the HSD sludge. Throughout this study the hydrogen percentage in the headspace of the digesters was greater than 50% and no methanogenesis was observed. The results emphasize that hydrogen significantly inhibited the hydrogen-producing activity of sludge when initial microcrystalline cellulose concentrations exceeded 25.0 g/L. A further 25 batch experiments performed with full factorial design incorporating multivariate analysis suggested that the ability of the sludge to convert cellulose into hydrogen was influenced mainly by the ratio of initial cellulose concentration (So) to initial sludge density (Xo), but not by interaction between the variables. The hydrogen-producing activity depended highly on interaction of So x (So/Xo). Through response surface analysis it was found that a maximum hydrogen yield of 3.2 mmol/g cellulose occurred at So = 40 g/L and So/Xo = 8 g cellulose/g VSS. A high specific rate of 18 mmol/(g VSS-d) occurred at So = 28 g/L and So/Xo = 9 g cellulose/g VSS. These experimental results suggest that high hydrogen generation from cellulose was accompanied by low So/Xo.

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H2 production through anaerobic mixed culture: effect of batch S0/X0 and shock loading in CSTR

Fan

Chen

2004

Chemosphere

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End products and molar growth yield of Clostridium fallax isolated from an anaerobic digester

Cited by 8 publications

References 14 publications

Thermodynamic analysis of product formation in mesophilic acidogenesis of lactose

Thermodynamic analysis of product formation in mesophilic acidogenesis of lactose

Biohydrogen generation by mesophilic anaerobic fermentation of microcrystalline cellulose

H2 production through anaerobic mixed culture: effect of batch S0/X0 and shock loading in CSTR

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