The photoheterotrophic H2 evolution of Rhodobacter sphaeroides is enhanced in the presence of ethanol

Oh, Eun Kyoung; Kim, Eui-Jin; Hwang, Hyae-Jeong; Tong, Xiaomeng; Nam, Jeong-Min; Kim, Mi-Sun; Lee, Chang Kyu

doi:10.1016/j.ijhydene.2012.08.029

Cited by 9 publications

(4 citation statements)

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“…This may be an indication of metabolic adaptations affecting the H 2 -producing enzymes, thereby leading to distinct H 2 production profiles (Figure 1 D and F). Interestingly, it has recently been shown that the nitrogenase-mediated H 2 evolution in a photoheterotrophic bacterium Rhodobacter sphaeroides was enhanced by ethanol [ 35 , 36 ]. Oh et al .…”

Section: Resultsmentioning

confidence: 99%

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Genome-wide transcriptional analysis suggests hydrogenase- and nitrogenase-mediated hydrogen production in Clostridium butyricum CWBI 1009

Całusińska

Hamilton

Monsieurs

et al. 2015

Biotechnol Biofuels

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BackgroundMolecular hydrogen, given its pollution-free combustion, has great potential to replace fossil fuels in future transportation and energy production. However, current industrial hydrogen production processes, such as steam reforming of methane, contribute significantly to the greenhouse effect. Therefore alternative methods, in particular the use of fermentative microorganisms, have attracted scientific interest in recent years. However the low overall yield obtained is a major challenge in biological H2 production. Thus, a thorough and detailed understanding of the relationships between genome content, gene expression patterns, pathway utilisation and metabolite synthesis is required to optimise the yield of biohydrogen production pathways.ResultsIn this study transcriptomic and proteomic analyses of the hydrogen-producing bacterium Clostridium butyricum CWBI 1009 were carried out to provide a biomolecular overview of the changes that occur when the metabolism shifts to H2 production. The growth, H2-production, and glucose-fermentation profiles were monitored in 20 L batch bioreactors under unregulated-pH and fixed-pH conditions (pH 7.3 and 5.2). Conspicuous differences were observed in the bioreactor performances and cellular metabolisms for all the tested metabolites, and they were pH dependent. During unregulated-pH glucose fermentation increased H2 production was associated with concurrent strong up-regulation of the nitrogenase coding genes. However, no such concurrent up-regulation of the [FeFe] hydrogenase genes was observed. During the fixed pH 5.2 fermentation, by contrast, the expression levels for the [FeFe] hydrogenase coding genes were higher than during the unregulated-pH fermentation, while the nitrogenase transcripts were less abundant. The overall results suggest, for the first time, that environmental factors may determine whether H2 production in C. butyricum CWBI 1009 is mediated by the hydrogenases and/or the nitrogenase.ConclusionsThis work, contributing to the field of dark fermentative hydrogen production, provides a multidisciplinary approach for the investigation of the processes involved in the molecular H2 metabolism of clostridia. In addition, it lays the groundwork for further optimisation of biohydrogen production pathways based on genetic engineering techniques.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0203-5) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

“…Oh et al . [ 36 ] reported a 60% increase in H 2 production in the presence of ethanol in the ammonium-containing medium. Moreover, the authors showed that the increased nitrogenase activity was regulated at the level of nifHDK transcription and that ethanol was not used as a carbon source by the bacterium.…”

Section: Resultsmentioning

confidence: 99%

Genome-wide transcriptional analysis suggests hydrogenase- and nitrogenase-mediated hydrogen production in Clostridium butyricum CWBI 1009

Całusińska

Hamilton

Monsieurs

et al. 2015

Biotechnol Biofuels

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“…Accordingly, the ratios of both NADH/NAD + and NADPH/NADP + were lowered to 40% to 70% of the control values that were determined in the absence of ethanol (Figure 6 c). Since the nitrogenase activity of R. sphaeroides is elevated in the presence of ethanol [ 19 ], the consumption of reducing power appears to be accelerated by ethanol. Previously, an increase in the cellular NAD + level was also observed following the deletion of nonessential metabolic pathways in R. sphaeroides [ 27 ].…”

Section: Resultsmentioning

confidence: 99%

“…Electron balances were established to evaluate electron partitioning of lactate into H 2 , cell biomass, and SMPs. As a gradual drop in H 2 production was observed during continuous operation, 0.2% (v/v) ethanol was externally added to the medium, since it has recently been shown that the presence of ethanol can enhance H 2 production by R. sphaeroides [ 19 ]. In addition, size exclusion chromatography (SEC) and excitation-emission matrix (EEM) analysis were carried out to characterize the SMPs produced during photo-fermentation.…”

Section: Introductionmentioning

confidence: 99%

Enhanced photo-fermentative H2 production using Rhodobacter sphaeroides by ethanol addition and analysis of soluble microbial products

Kim

Lee

Kang

et al. 2014

Biotechnol Biofuels

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BackgroundBiological fermentation routes can provide an environmentally friendly way of producing H2 since they use renewable biomass as feedstock and proceed under ambient temperature and pressure. In particular, photo-fermentation has superior properties in terms of achieving high H2 yield through complete degradation of substrates. However, long-term H2 production data with stable performance is limited, and this data is essential for practical applications. In the present work, continuous photo-fermentative H2 production from lactate was attempted using the purple non-sulfur bacterium, Rhodobacter sphaeroides KD131. As a gradual drop in H2 production was observed, we attempted to add ethanol (0.2% v/v) to the medium.ResultsAs continuous operation went on, H2 production was not sustained and showed a negligible H2 yield (< 0.5 mol H2/mol lactateadded) within two weeks. Electron balance analysis showed that the reason for the gradual drop in H2 production was ascribed to the increase in production of soluble microbial products (SMPs). To see the possible effect of ethanol addition, a batch test was first conducted. The presence of ethanol significantly increased the H2 yield from 1.15 to 2.20 mol H2/mol lactateadded, by suppressing the production of SMPs. The analysis of SMPs by size exclusion chromatography showed that, in the later period of fermentation, more than half of the low molecular weight SMPs (< 1 kDa) were consumed and used for H2 production when ethanol had been added, while the concentration of SMPs continuously increased in the absence of ethanol. It was found that the addition of ethanol facilitated the utilization of reducing power, resulting in an increase in the cellular levels of NAD+ and NADP+. In continuous operation, ethanol addition was effective, such that stable H2 production was attained with an H2 yield of 2.5 mol H2/mol lactateadded. Less than 15% of substrate electrons were used for SMP production, whereas 35% were used in the control.ConclusionsWe have found that SMPs are the key factor in photo-fermentative H2 production, and their production can be suppressed by ethanol addition. However, since external addition of ethanol to the medium represents an extra economic burden, ethanol should be prepared in a cost-effective way.

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Polyhydroxybutyrate production in one-stage by purple phototrophic bacteria: Influence of alkaline pH, ethanol, and C/N ratios

Montiel-Corona

Buitrón

2022

Biochemical Engineering Journal

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The photoheterotrophic H2 evolution of Rhodobacter sphaeroides is enhanced in the presence of ethanol

Cited by 9 publications

References 36 publications

Genome-wide transcriptional analysis suggests hydrogenase- and nitrogenase-mediated hydrogen production in Clostridium butyricum CWBI 1009

Genome-wide transcriptional analysis suggests hydrogenase- and nitrogenase-mediated hydrogen production in Clostridium butyricum CWBI 1009

Enhanced photo-fermentative H2 production using Rhodobacter sphaeroides by ethanol addition and analysis of soluble microbial products

Polyhydroxybutyrate production in one-stage by purple phototrophic bacteria: Influence of alkaline pH, ethanol, and C/N ratios

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