Carbon Monoxide as an Electron Donor for the Biological Reduction of Sulphate

Parshina, Sofiya N.; Sipma, Jan; Henstra, Anne M.; Stams, A.J.M.

doi:10.1155/2010/319527

Cited by 48 publications

(32 citation statements)

References 79 publications

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“…The inhibition may be because of adverse effects of CO on metalloenzymes, such as hydrogenases, with which CO can competitively form stable complexes that block the interactions of substrate and enzymes (35). Compared with the reported CO concentrations [1-2%, 7.5%, and 50-100% (vol/vol)] that cause severe inhibition to other anaerobes with hydrogenases, the severe CO toxicity level of strain 195 [6 μmol per bottle, (∼0.1%) (vol/vol)] is orders-of-magnitudes lower (36,37). This extreme CO toxicity is likely one reason that growth of axenic D. mccartyi cultures is observably unreliable (20)(21)(22)(23).…”

Section: Discussionmentioning

confidence: 92%

Incomplete Wood–Ljungdahl pathway facilitates one-carbon metabolism in organohalide-respiring Dehalococcoides mccartyi

Zhuang

Bill

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

100

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The acetyl-CoA "Wood-Ljungdahl" pathway couples the folatemediated one-carbon (C1) metabolism to either CO 2 reduction or acetate oxidation via acetyl-CoA. This pathway is distributed in diverse anaerobes and is used for both energy conservation and assimilation of C1 compounds. Genome annotations for all sequenced strains of Dehalococcoides mccartyi, an important bacterium involved in the bioremediation of chlorinated solvents, reveal homologous genes encoding an incomplete Wood-Ljungdahl pathway. Because this pathway lacks key enzymes for both C1 metabolism and CO 2 reduction, its cellular functions remain elusive. Here we used D. mccartyi strain 195 as a model organism to investigate the metabolic function of this pathway and its impacts on the growth of strain 195. Surprisingly, this pathway cleaves acetyl-CoA to donate a methyl group for production of methyltetrahydrofolate (CH 3 -THF) for methionine biosynthesis, representing an unconventional strategy for generating CH 3 -THF in organisms without methylene-tetrahydrofolate reductase. Carbon monoxide (CO) was found to accumulate as an obligate by-product from the acetyl-CoA cleavage because of the lack of a CO dehydrogenase in strain 195. CO accumulation inhibits the sustainable growth and dechlorination of strain 195 maintained in pure cultures, but can be prevented by CO-metabolizing anaerobes that coexist with D. mccartyi, resulting in an unusual syntrophic association. We also found that this pathway incorporates exogenous formate to support serine biosynthesis. This study of the incomplete Wood-Ljungdahl pathway in D. mccartyi indicates a unique bacterial C1 metabolism that is critical for D. mccartyi growth and interactions in dechlorinating communities and may play a role in other anaerobic communities.reductive dechlorination | 13 C isotope analysis | acetyl-CoA synthase

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Section: Discussionmentioning

confidence: 92%

Incomplete Wood–Ljungdahl pathway facilitates one-carbon metabolism in organohalide-respiring Dehalococcoides mccartyi

Zhuang

Bill

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

100

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“…For instance, sulfate reducing, Fe(II)- and sulfide-oxidizing, and phototrophic bacterial activities may be exploited for removal of SO 2 (Dasu et al, 1993; Huber and Stetter, 1998; Pandy et al, 2005; Parshina et al, 2005, 2010), though these activities have not been considered in the context of existing FGD systems. Given the high operating temperatures associated with FGD units, thermophilic microorganisms would be best suited for biotechnological approaches to FGD and SO 2 removal (Huber and Stetter, 1998).…”

Section: Introductionmentioning

confidence: 99%

Microbial communities associated with wet flue gas desulfurization systems

Brown¹,

Brown²,

Senko³

2012

Front. Microbio.

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Flue gas desulfurization (FGD) systems are employed to remove SOx gasses that are produced by the combustion of coal for electric power generation, and consequently limit acid rain associated with these activities. Wet FGDs represent a physicochemically extreme environment due to the high operating temperatures and total dissolved solids (TDS) of fluids in the interior of the FGD units. Despite the potential importance of microbial activities in the performance and operation of FGD systems, the microbial communities associated with them have not been evaluated. Microbial communities associated with distinct process points of FGD systems at several coal-fired electricity generation facilities were evaluated using culture-dependent and -independent approaches. Due to the high solute concentrations and temperatures in the FGD absorber units, culturable halothermophilic/tolerant bacteria were more abundant in samples collected from within the absorber units than in samples collected from the makeup waters that are used to replenish fluids inside the absorber units. Evaluation of bacterial 16S rRNA genes recovered from scale deposits on the walls of absorber units revealed that the microbial communities associated with these deposits are primarily composed of thermophilic bacterial lineages. These findings suggest that unique microbial communities develop in FGD systems in response to physicochemical characteristics of the different process points within the systems. The activities of the thermophilic microbial communities that develop within scale deposits could play a role in the corrosion of steel structures in FGD systems.

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“…With the exception of some Desulfotomaculum species that can grow in Ͼ50% CO, CO is toxic at concentrations of Ͻ20% to most sulfate-reducing bacteria (21). CO toxicity is likely to be a result of inhibition of hydrogenases or other metalloenzymes (21).…”

mentioning

confidence: 99%

“…CO toxicity is likely to be a result of inhibition of hydrogenases or other metalloenzymes (21). CO has been demonstrated to be both produced and consumed by Desulfovibrio spp.…”

mentioning

confidence: 99%

Deletion of the Desulfovibrio vulgaris Carbon Monoxide Sensor Invokes Global Changes in Transcription

et al. 2012

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The carbon monoxide-sensing transcriptional factor CooA has been studied only in hydrogenogenic organisms that can grow using CO as the sole source of energy. Homologs for the canonical CO oxidation system, including CooA, CO dehydrogenase (CODH), and a CO-dependent Coo hydrogenase, are present in the sulfate-reducing bacterium Desulfovibrio vulgaris, although it grows only poorly on CO. We show that D. vulgaris Hildenborough has an active CO dehydrogenase capable of consuming exogenous CO and that the expression of the CO dehydrogenase, but not that of a gene annotated as encoding a Coo hydrogenase, is dependent on both CO and CooA. Carbon monoxide did not act as a general metabolic inhibitor, since growth of a strain deleted for cooA was inhibited by CO on lactate-sulfate but not pyruvate-sulfate. While the deletion strain did not accumulate CO in excess, as would have been expected if CooA were important in the cycling of CO as a metabolic intermediate, global transcriptional analyses suggested that CooA and CODH are used during normal metabolism. Desulfovibrio organisms are sulfate-reducing bacteria that use organic acids, alcohols, or molecular hydrogen as electron donors to reduce sulfate (22). When these bacteria grow on organic acids or alcohols, energy generation is hypothesized to be derived in part through hydrogen cycling (20). Hydrogen cycling posits that reducing equivalents formed during oxidation of the electron donor in the cytoplasm are shuttled to form hydrogen, which is then oxidized in the periplasm to generate electrons for sulfate reduction and to generate a proton motive force. This mechanism for energy recovery offers an explanation for the hydrogen burst observed during the early growth phase in batch culture (15,19,20,28). Desulfovibrio vulgaris Hildenborough appears well equipped to carry out this hydrogen cycling, possessing an array of six predicted hydrogenases-four localized periplasmically (Hyd, Hyn1, Hyn2, and Hys) and two membrane-bound enzymes facing the cytoplasm (Coo and Ech) (12). There is also some evidence suggesting that, in addition to hydrogen, carbon monoxide functions as either a growth substrate or an intermediate in energy metabolism (16,29).With the exception of some Desulfotomaculum species that can grow in Ͼ50% CO, CO is toxic at concentrations of Ͻ20% to most sulfate-reducing bacteria (21). CO toxicity is likely to be a result of inhibition of hydrogenases or other metalloenzymes (21). CO has been demonstrated to be both produced and consumed by Desulfovibrio spp. CO production has been documented during growth of both D. vulgaris Hildenborough (29) and D. vulgaris Madison (16) on lactate-sulfate or pyruvate-sulfate, with greater accumulation in a D. vulgaris Hildenborough hyd mutant lacking the periplasmic Fe hydrogenase (29). Consumption was demonstrated in D. vulgaris strain Madison. This organism grew on a headspace of 4% CO as the sole energy source and tolerated a headspace of 4.5% CO while growing on organic acids, consistent with the presence of an acti...

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Carbon Monoxide as an Electron Donor for the Biological Reduction of Sulphate

Cited by 48 publications

References 79 publications

Incomplete Wood–Ljungdahl pathway facilitates one-carbon metabolism in organohalide-respiring Dehalococcoides mccartyi

Incomplete Wood–Ljungdahl pathway facilitates one-carbon metabolism in organohalide-respiring Dehalococcoides mccartyi

Microbial communities associated with wet flue gas desulfurization systems

Deletion of the Desulfovibrio vulgaris Carbon Monoxide Sensor Invokes Global Changes in Transcription

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