Acetate production from lactose by Clostridium thermolacticum and hydrogen-scavenging microorganisms in continuous culture—Effect of hydrogen partial pressure

Fermentative hydrogen production has often been described as inhibited by its own gas production. In this work, hydrogen production by Clostridium butyricum was investigated in batch Biochemical Hydrogen Potential (BHP) tests and in a 2.5 L Anaerobic Sequenced Batch Reactor (AnSBR) under different operating conditions regarding liquid-to-gas mass transfer.Through the addition of both stirring up to 400 RPM and nitrogen sparging, the yields were enhanced from 1.6 to 3.1 mol H2 ·mol glucose -1 and the maximum hydrogen production rates from 140 to 278 mL·h -1 . These original results were achieved with a pure Clostridium strain. They showed that hydrogen production was improved by a higher liquid-to-gas hydrogen transfer resulting in a lower dissolved hydrogen concentration in the culture medium and therefore in a lower bacterial inhibition. In addition, biohydrogen partitioning between the gas and the liquid phase did not conform to Henry's Law due to critical supersaturation phenomena up to seven-fold higher than the equilibrium conditions. Therefore dissolved hydrogen concentration should be systematically measured instead of the headspace hydrogen partial pressure. A model was proposed to correlate H 2 production yield and rate by the pure C.butyricum strain CWBI1009 with mass transfer coefficient K L a.

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“…These results are in accordance with previous studies on hydrogenproducing Clostridium strains [8,34,45].…”

Section: Metabolite Productionsupporting

confidence: 93%

“…On the other hand, conditions in the bioreactor headspace leading to a lower hydrogen partial pressure also enhanced hydrogen production performance. This was evidenced by gas flushing with N 2 or H 2 [24,48,49], by applying higher [23,52] or lower total pressure [8,9,11,25,45,52].…”

Section: Discussionmentioning

confidence: 99%

Investigation of the links between mass transfer conditions, dissolved hydrogen concentration and biohydrogen production by the pure strain Clostridium butyricum CWBI1009

Beckers

Masset

Hamilton

et al. 2015

Biochemical Engineering Journal

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“…The model developed assumes that all the net NADH produced (in order to maximize ATP production) can be converted into molecular hydrogen. This assumption is unlikely to be correct because at the actual hydrogen partial pressures hydrogen production from NADH is thermodynamically unfavorable (DG 0' is þ18.1 kJ mol À1 ) (Collet et al, 2005). Also the experimental evidence points out that hydrogen is in fact only produced in the conversion of pyruvate to acetyl-CoA.…”

Section: Comparison With Theoretical Predictionsmentioning

confidence: 99%

“…These two are both capable of inducing hydrogen production. Thermodynamically, reduced ferredoxin is a stronger electron donor compared to NADH and the reduction of protons by a hydrogenase into molecular hydrogen is more favorable (Collet et al, 2005; circles and black squares, respectively); Gibbs free energy of the reaction of bicarbonate and molecular hydrogen into formic acid (grey triangles). The lines are the estimated fractions calculated from the average free energy of the conversion of bicarbonate into formate (6.5 kJ/mol), considering the actual bicarbonate concentration and the total amount of H 2 and formate produced.…”

Section: Formate Versus Co 2 /Hmentioning

confidence: 99%

Influence of the pH on (open) mixed culture fermentation of glucose: A chemostat study

Temudo

Kleerebezem

Loosdrecht

2007

Biotech & Bioengineering

216

198

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Catabolic products from anaerobic fermentation processes are potentially of industrial interest. The volatile fatty acids and alcohols produced can be used as building blocks in chemical processes or applied directly as substrates in a mixed culture process to produce bioplastics. Development of such applications requires a predictable and controllable product spectrum of the fermentation process. The aim of the research described in this paper was (i) to investigate the product spectrum of an open mixed culture fermentation (MCF) process as a function of the pH, using glucose as substrate, and (ii) to relate the product spectrum obtained to generalized biochemical and thermodynamic considerations. A chemostat was operated under carbon and energy limitation in order to investigate the pH effect on the product spectrum in a MCF process. A transition from CO(2)/H(2) production at lower pH values to formate production at higher pH values was observed. The ratio of CO(2)/H(2) versus formate production was found to be related to the thermodynamics of formate dehydrogenation to CO(2)/H(2). This transition was associated with a shift in the catabolic products, from butyrate and acetate to ethanol and acetate, likely due to a decrease in the oxidation state of the electron carriers in the cell. The product spectrum of the MCF process as a function of the pH could largely be explained using general biochemical considerations.

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“…Many studies have examined the syntrophic growth of sulfate-reducing bacteria (SRB) acting like secondary fermenters and methanogenic archaea [9][10][11] . Most recently, the metabolic interaction between Clostridia, acting as primary fermenters, and methanogenic archaea has also been studied 12,13 , highlighting a symbiotic process of interspecies hydrogen transfer that does not require physical interaction. However, very few studies have examined interaction between SRB and Clostridia, and little is known about the complex interactions that occur in natural bacterial consortia and how primary fermenter bacteria such as Clostridia compete with other anaerobes like SRB 8 .…”

mentioning

confidence: 99%

Nutritional stress induces exchange of cell material and energetic coupling between bacterial species

et al. 2015

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Knowledge of the behaviour of bacterial communities is crucial for understanding biogeochemical cycles and developing environmental biotechnology. Here we demonstrate the formation of an artificial consortium between two anaerobic bacteria, Clostridium acetobutylicum (Gram-positive) and Desulfovibrio vulgaris Hildenborough (Gram-negative, sulfate-reducing) in which physical interactions between the two partners induce emergent properties. Molecular and cellular approaches show that tight cell-cell interactions are associated with an exchange of molecules, including proteins, which allows the growth of one partner (D. vulgaris) in spite of the shortage of nutrients. This physical interaction induces changes in expression of two genes encoding enzymes at the pyruvate crossroads, with concomitant changes in the distribution of metabolic fluxes, and allows a substantial increase in hydrogen production without requiring genetic engineering. The stress induced by the shortage of nutrients of D. vulgaris appears to trigger the interaction.

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Acetate production from lactose by Clostridium thermolacticum and hydrogen-scavenging microorganisms in continuous culture—Effect of hydrogen partial pressure

Cited by 29 publications

References 26 publications

Investigation of the links between mass transfer conditions, dissolved hydrogen concentration and biohydrogen production by the pure strain Clostridium butyricum CWBI1009

Investigation of the links between mass transfer conditions, dissolved hydrogen concentration and biohydrogen production by the pure strain Clostridium butyricum CWBI1009

Influence of the pH on (open) mixed culture fermentation of glucose: A chemostat study

Nutritional stress induces exchange of cell material and energetic coupling between bacterial species

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