Pyruvate fermentation in Rhodospirillum rubrum and after transfer from aerobic to anaerobic conditions in the dark

Schön, G.; Voelskow, H.

doi:10.1007/bf00427872

Cited by 38 publications

(14 citation statements)

References 18 publications

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“…The reductant is disposed of by the reduction of protons to H2. (24), and, under conditions of nitrogen starvation, nitrogenase (20). We think that the hydrogenase activity reported here is distinct from each of these.…”

Section: Discussionmentioning

confidence: 51%

Regulation of carbon monoxide dehydrogenase and hydrogenase in Rhodospirillum rubrum: effects of CO and oxygen on synthesis and activity

et al. 1989

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Exposure of the photosynthetic bacterium Rhodospirillum rubrum to carbon monoxide led to increased carbon monoxide dehydrogenase and hydrogenase activities due to de novo protein synthesis of both enzymes. Two-dimensional gels of [35S]methionine-pulse-labeled cells showed that induction of CO dehydrogenase synthesis was rapidly initiated (<5 min upon exposure to CO) and was inhibited by oxygen. Both CO dehydrogenase and the CO-induced hydrogenase were inactivated by oxygen in vivo and in vitro. In contrast to CO dehydrogenase, the CO-induced hydrogenase was 95% inactivated by heating at 70°C for 5 min. Unlike other hydrogenases, this CO-induced hydrogenase was inhibited only 60% by a 100% CO gas phase.A diverse set of bacteria possess the ability to oxidize CO to CO2 (for reviews, see references 10 through 12, 14, 15, 18, 26, and 30). In acetogenic and methanogenic bacteria, CO is oxidized by multisubunit nickel-containing CO dehydrogenase complexes (8,9,21). The expression of these enzymes is not affected by the presence or absence of CO, and these enzymes appear to be involved in acetate metabolism, with CO oxidation being a secondary reaction (15,29,30).Aerobic carboxydotrophic bacteria oxidize CO by using carbon monoxide oxidase, an oxygen-stable iron-sulfur enzyme containing flavin and molybdopterin (16)(17)(18). In these bacteria CO oxidase is induced by the presence of CO, and hydrogenase is induced in cells grown with CO or with CO2 and H2 (18).Some photosynthetic bacteria tolerate CO (13), and Rhodocyclus (formerly Rhodopseudomonas) gelatinosus has been shown by Uffen and co-workers to utilize CO as its sole carbon and energy source during anaerobic growth in the dark (25). The membrane-bound CO-oxidizing system of R. gelatinosus is inducible by CO and produces CO2 and H2 as products of the oxidation of CO (27,28). CO-dependent evolution of H2 from extracts of Rhodospirillum rubrum S1 has been noted (26). We have previously reported COdependent formation of H2 and CO2 by R. rubrum cells grown in the light on ammonium-malate medium (6) and that exposure of light-grown R. rubrum cultures to CO led to significantly increased levels of CO dehydrogenase (4).In this paper these initial observations are extended to demonstrate that CO induces two enzymatic activities, CO dehydrogenase and a CO-insensitive hydrogenase, which appear to function together to accomplish the oxidation of CO to CO2 and H2. These activities are inactivated by 02 both in vivo and in vitro, and the synthesis of CO dehydrogenase is shown to be inhibited by oxygen. Chromatophore suspensions. Membrane preparations (chromatophores) were derived from cells which had been treated with CO for 24 h before harvest. Cells were broken and the chromatophores were collected by centrifugation as previously described (4) and stored in liquid nitrogen.Enzyme assays. CO dehydrogenase activity was assayed by using a CO-dependent methyl viologen reduction assay as previously described (6). Cells were lysed by grinding before the assay for CO dehydrogenas...

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Section: Discussionmentioning

confidence: 51%

Regulation of carbon monoxide dehydrogenase and hydrogenase in Rhodospirillum rubrum: effects of CO and oxygen on synthesis and activity

et al. 1989

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“…Biological hydrogen production from formate is catalyzed by the formate hydrogen lyase (FHL) complex. The complex exists in various microbial genera, including Enterobacter, Methanogenes, and photosynthetic bacteria (7,12,24). Among these, the FHL complex of E. coli has been the most extensively characterized at both the physiological and genetic levels.…”

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confidence: 99%

Enhanced Hydrogen Production from Formic Acid by Formate Hydrogen Lyase-Overexpressing Escherichia coli Strains

Yoshida

Nishimura

Kawaguchi

et al. 2005

Appl Environ Microbiol

206

113

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Genetic recombination of Escherichia coli in conjunction with process manipulation was employed to elevate the efficiency of hydrogen production in the resultant strain SR13 2 orders of magnitude above that of conventional methods. The formate hydrogen lyase (FHL)-overexpressing strain SR13 was constructed by combining FHL repressor (hycA) inactivation with FHL activator (fhlA) overexpression. Transcription of large-subunit formate dehydrogenase, fdhF, and large-subunit hydrogenase, hycE, in strain SR13 increased 6.5-and 7.0-fold, respectively, compared to the wild-type strain. On its own, this genetic modification effectively resulted in a 2.8-fold increase in hydrogen productivity of SR13 compared to the wild-type strain. Further enhancement of productivity was attained by using a novel method involving the induction of the FHL complex with high-cell-density filling of a reactor under anaerobic conditions. Continuous hydrogen production was achieved by maintaining the reactor concentration of the substrate (free formic acid) under 25 mM. An initial productivity of 23.6 g hydrogen h ؊1 liter ؊1 (300 liters h ؊1 liter ؊1 at 37°C) was achieved using strain SR13 at a cell density of 93 g (dry weight) cells/liter. The hydrogen productivity reported in this work has great potential for practical application.In recent years, much attention has been paid to hydrogen as a renewable energy source as a result of the projected decrease in fossil fuel reserves on the one hand and improvements in hydrogen fuel cell technology on the other (3). A wide range of applications of hydrogen, from cars to small devices, is anticipated. The well-established method for hydrogen production in which oil or natural gas is chemically refined occurs at high temperatures and pressures. In contrast, the less well-established biological methods have the merit of obviating the production of carbon monoxide, which is extremely harmful to the electrodes of hydrogen fuel cells. In addition, biological reactions occur at ambient temperatures and pressures, thus lowering the energy requirements of the production process.Microorganisms produce hydrogen via two main pathways: photosynthesis and fermentation. Oxygenic photosynthetic microorganisms include Chlamydomonas reinhardtii, while anoxygenic photosynthetic microorganisms include Rhodobacter sphaeroides. On the other hand, fermentation is the pathway used by facultative anaerobes, such as Escherichia coli and Enterobacter species, and by strict anaerobes, such as Clostridium species (6,13,18,19,25). In general, the fermentative hydrogen productivity per cell is higher than the productivity achieved by photosynthetic organisms. Biohydrogen productivities of 151.2 mg hydrogen h Ϫ1 liter Ϫ1 by Enterobacter cloacae IIT-BT 08 and 605 mg hydrogen h Ϫ1 liter Ϫ1 (7.4 liters h Ϫ1

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“…Several studies have focused on increasing the efficiency of H 2 production by optimization of growth conditions [5–9], co-culture cultivations [10–12], genetic engineering on H 2 -producing or uptake enzymes [13–16] and the alteration of other regulatory mechanisms [17]. Rhodospirillum rubrum is one of the best model strains for the study of H 2 production, since it has several pathways to produce H 2 , including nitrogenase [18], CO-induced Ni-Fe hydrogenase [19–21], pyruvate-formate hydrogenase [22–24] and other hydrogenases [25]. In R. rubrum , nitrogenase is the main route for H 2 production under photosynthetic and nitrogen-limiting conditions and it can efficiently produce nearly pure H 2 gas (>85% H 2 content) without O 2 as a byproduct [26].…”

Section: Introductionmentioning

confidence: 99%

Elimination of Rubisco alters the regulation of nitrogenase activity and increases hydrogen production in Rhodospirillum rubrum

Wang

Zhang

Welch

et al. 2010

International Journal of Hydrogen Energy

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Nitrogenase not only reduces atmospheric nitrogen to ammonia, but also reduces protons to hydrogen (H 2 ). The nitrogenase system is the primary means of H 2 production under photosynthetic and nitrogen-limiting conditions in many photosynthetic bacteria, including Rhodospirillum rubrum. The efficiency of this biological H 2 production largely depends on the nitrogenase enzyme and the availability of ATP and electrons in the cell. Previous studies showed that blockage of the CO 2 fixation pathway in R. rubrum induced nitrogenase activity even in the presence of ammonium, presumably to remove excess reductant in the cell. We report here the recharacterization of cbbM mutants in R. rubrum to study the effect of Rubisco on H 2 production. Our newly constructed cbbM mutants grew poorly in malate medium under anaerobic conditions. However, the introduction of constitutively active NifA (NifA*), the transcriptional activator of the nitrogen fixation (nif) genes, allows cbbM mutants to dissipate the excess reductant through the nitrogenase system and improves their growth. Interestingly, we found that the deletion of cbbM alters the posttranslational regulation of nitrogenase activity, resulting in partially active nitrogenase in the presence of ammonium. The combination of mutations in nifA, draT and cbbM greatly increased H 2 production of R. rubrum, especially in the presence of excess of ammonium. Furthermore, these mutants are able to produce H 2 over a much longer time frame than the wild type, increasing the potential of these recombinant strains for the biological production of H 2 .

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Pyruvate fermentation in Rhodospirillum rubrum and after transfer from aerobic to anaerobic conditions in the dark

Cited by 38 publications

References 18 publications

Regulation of carbon monoxide dehydrogenase and hydrogenase in Rhodospirillum rubrum: effects of CO and oxygen on synthesis and activity

Regulation of carbon monoxide dehydrogenase and hydrogenase in Rhodospirillum rubrum: effects of CO and oxygen on synthesis and activity

Enhanced Hydrogen Production from Formic Acid by Formate Hydrogen Lyase-Overexpressing Escherichia coli Strains

Elimination of Rubisco alters the regulation of nitrogenase activity and increases hydrogen production in Rhodospirillum rubrum

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