Phototrophic bacteria produce volatile, methylated sulfur and selenium compounds

McCarthy, Steven J; CHASTEEN, T. G.; Marshall, M; Fall, Ray; Bachofen, Reinhard

doi:10.1111/j.1574-6968.1993.tb06429.x

Cited by 35 publications

(28 citation statements)

References 10 publications

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“…Dimethyl sulfoxide, an oxidation product of DMSP, is reduced to DMS by several marine sulfate-reducing bacteria (25). Phototrophic nonsulfur bacteria produce DMS during photosynthesis (38).Given the variety of reactions generating different methylated thiols from abundant environmental precursors, it is not surprising that methanogenic bacteria have been found to produce methane from these compounds. DMS and MSH are active methane precursors in freshwater sediments and sewage sludge (61), as well as in estuarine and alkaline or hypersaline sediments (27).…”

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confidence: 99%

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Methylthiol:coenzyme M methyltransferase from Methanosarcina barkeri, an enzyme of methanogenesis from dimethylsulfide and methylmercaptopropionate

Tallant

Krzycki

1997

J Bacteriol

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Dimethylsulfide (DMS) and related methylated thiols play significant roles in the ecosystem. DMS generated in the open ocean has been implicated as the major source of cloud condensation nuclei present in the marine atmosphere, with subsequent global effects on climate (9). A major source of DMS and other methylated thiols is dimethylsulfoniopropionate (DMSP), a compatible solute found in a diverse array of organisms including algae (29), reef corals, diatoms (21), and some plants (44). Concentrations of DMSP (56) and DMS (57) can be in the micromolar range in cyanobacterial mats and salt marsh sediments. DMSP can be directly metabolized by two major routes in the environment (56). It can be directly cleaved to DMS and acrylic acid by bacteria and algae, using DMSP lyase (11,12,35). DMSP can also be sequentially demethylated under aerobic or anaerobic conditions to yield 3-methylmercaptopropionate (MMPA) and 3-mercaptopropionic acid (MPA) (52, 56). Aerobic bacteria producing methanethiol (MSH) from either DMSP or MMPA have been described (52).DMS is also formed from several other processes. Methionine added to anaerobic sediments produces MSH and lesser amounts of DMS (28). DMS and MSH are also made from methoxylated aromatics and sulfide by some homoacetogens (1, 30). Dimethyl sulfoxide, an oxidation product of DMSP, is reduced to DMS by several marine sulfate-reducing bacteria (25). Phototrophic nonsulfur bacteria produce DMS during photosynthesis (38).Given the variety of reactions generating different methylated thiols from abundant environmental precursors, it is not surprising that methanogenic bacteria have been found to produce methane from these compounds. DMS and MSH are active methane precursors in freshwater sediments and sewage sludge (61), as well as in estuarine and alkaline or hypersaline sediments (27). Pure cultures of methanogens that grow on DMS and/or MSH include Methanolobus taylorii 42,43), Methanolobus bombayensis (26), Methanosarcina siciliae (40, 41), Methanosarcina sp. strain MTP4 (19), Methanosarcina acetivorans (41, 49), Methanohalophilus oregonense (36), and Methanohalophilus zhilinae (37). Recently, the three Methanosarcina spp. in this list were found to also grow on MMPA as well as DMS (53,54).Methanogens which can produce methane from methylated thiols typically consume other methylotrophic methanogenic substrates such as methylamines and methanol. Coenzyme M (CoM) is methylated by methylotrophic substrates as an intermediate step to both methane and carbon dioxide formation (17). Proteins mediating the methylation of CoM with trimethylamine (TMA) (15, 16), monomethylamine (MMA) (4, 6), and methanol (47, 55) have been isolated. In each pathway, a distinct corrinoid protein is methylated with the methylotrophic substrate by a substrate-specific polypeptide. The methylated corrinoid protein then serves as the substrate for one of two isoforms of methylcobamide:CoM methyltransferase (MT2) termed MT2-M and MT2-A. MT2-A is used for methylamine metabolism, while MT2-M is used for meth...

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confidence: 99%

Methylthiol:coenzyme M methyltransferase from Methanosarcina barkeri, an enzyme of methanogenesis from dimethylsulfide and methylmercaptopropionate

Tallant

Krzycki

1997

J Bacteriol

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“…Selenate (SeO 4 2Ϫ ) and selenite (SeO 3 2Ϫ ) seem to be the most abundant forms of bioavailable selenium in the environment, and both can serve as electron acceptors for many microorganisms, including some phototrophic bacteria. These organisms are widespread and exhibit enormous metabolic and ecological diversity, and some are known to be able to use selenium oxyanions in their anaerobic metabolism (12,13,14,24). Rhodobacter sphaeroides is a purple nonsulfur bacterium that often serves as a model species for the group.…”

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Fate of Selenate and Selenite Metabolized by Rhodobacter sphaeroides

Fleet-Stalder

Chasteen

Pickering

et al. 2000

Appl Environ Microbiol

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Cultures of a purple nonsulfur bacterium, Rhodobacter sphaeroides, amended with ϳ1 or ϳ100 ppm selenate or selenite, were grown phototrophically to stationary phase. Analyses of culture headspace, separated cells, and filtered culture supernatant were carried out using gas chromatography, X-ray absorption spectroscopy, and inductively coupled plasma spectroscopy-mass spectrometry, respectively. While selenium-amended cultures showed much higher amounts of SeO 3 2؊ bioconversion than did analogous selenate experiments (94% uptake for SeO 3 2؊ as compared to 9.6% for SeO 4 2؊ -amended cultures from 100-ppm solutions), the chemical forms of selenium in the microbial cells were not very different except at exposure to high concentrations of selenite. Volatilization accounted for only a very small portion of the accumulated selenium; most was present in organic forms and the red elemental form.The roles of selenium in the biosphere, both beneficial and deleterious, are gradually being determined (2,5,7,15), and it is becoming apparent that bacteria play a major role in the global selenium cycle. Selenate (SeO 4 2Ϫ ) and selenite (SeO 3 2Ϫ ) seem to be the most abundant forms of bioavailable selenium in the environment, and both can serve as electron acceptors for many microorganisms, including some phototrophic bacteria. These organisms are widespread and exhibit enormous metabolic and ecological diversity, and some are known to be able to use selenium oxyanions in their anaerobic metabolism (12,13,14,24). Rhodobacter sphaeroides is a purple nonsulfur bacterium that often serves as a model species for the group. It can tolerate high concentrations of selenite and selenate (13,14) and can reduce and/or methylate these compounds (24).Recent work with phototrophic bacteria has shown that some can grow in the presence of 0.1, 1.0, even 10 mM selenate or selenite. Though growth rates were somewhat decreased, five phototrophic species grown on Sistrom minimal medium were shown to exhibit overall stationary-phase biomass production similar to that of controls. Methylated organosulfur, organoselenium, and dimethyl selenenyl sulfide have been detected in anaerobic culture headspace, and elemental Se was produced in some cultures (13,21,23). This reduction to the elemental form may be an important process in the biosphere, since soils from an evaporation pond in the Kesterson Reservoir show that, nearest the surface, Se 0 is the most prominent selenium species (16).Although it is relatively clear that phototrophic bacteria can grow in the presence of selenium oxyanions and that small amounts are reduced and/or methylated, little is known of the extent and path of this process. Here we report the results of quantifying and speciating selenium in the culture medium, the bacteria, and the gaseous headspace above the culture after R. sphaeroides was grown phototrophically in the presence of different concentrations of selenite and selenate to stationary phase. Cell supernatants were analyzed for total selenium using inductively co...

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“…These compounds arise in nature from processes such as the breakdown of methionine (8), reduction of dimethyl sulfoxide (9), anaerobic degradation of methoxylated aromatics (10,11), photosynthesis by some anoxygenic phototrophs (12), and demethylation of the osmolyte dimethylsulfoniopropionate (13,14). Since emission of DMS over the open ocean is thought to influence cloud formation, the metabolism of these compounds has wide-ranging implications (15).…”

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The MtsA Subunit of the Methylthiol:Coenzyme M Methyltransferase of Methanosarcina barkeri Catalyses Both Half-reactions of Corrinoid-dependent Dimethylsulfide: Coenzyme M Methyl Transfer

Tallant

Paul²,

Krzycki

2001

Journal of Biological Chemistry

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Phototrophic bacteria produce volatile, methylated sulfur and selenium compounds

Cited by 35 publications

References 10 publications

Methylthiol:coenzyme M methyltransferase from Methanosarcina barkeri, an enzyme of methanogenesis from dimethylsulfide and methylmercaptopropionate

Methylthiol:coenzyme M methyltransferase from Methanosarcina barkeri, an enzyme of methanogenesis from dimethylsulfide and methylmercaptopropionate

Fate of Selenate and Selenite Metabolized by Rhodobacter sphaeroides

The MtsA Subunit of the Methylthiol:Coenzyme M Methyltransferase of Methanosarcina barkeri Catalyses Both Half-reactions of Corrinoid-dependent Dimethylsulfide: Coenzyme M Methyl Transfer

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