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Metabolism of methylated sulfur compounds in anoxic salt marsh sediments

Thesis/Dissertation ·
OSTI ID:5964111

Methionine and dimethylsulfoniopropionate (DMSP) were identified as potential precursors of volatile organic sulfur compounds. Microbial hydrolysis of sulfur-carbon linkages resulted in the liberation of methane thiol (MSH) and dimethyl sulfide (DMS) from methionine and DMSP respectively. Sulfate reducing bacteria were responsible for some of the demethiolation of methionine. The hydrolysis of DMSP could not be assigned to any particular group of microorganisms, but this reaction occurred readily in biologically active sediments. An additional precursor for DMS was found to be Dimethyl sulfoxide (DMSO), which was reduced by sediment microbes to form DMS. Volatile methylated sulfur compounds such as DMS, MSH and dimethyl disulfide (DMDS) were observed to be transformed during their microbial metabolism to MSH, DMS, and MSH, respectively. Ultimately, methylated sulfur compounds were consumed by biological processes and converted to CO/sub 2/, CH/sub 4/ and H/sub 2/S. Both sulfate reducing and methane producing bacteria were involved in the observed transformations. Sediment methanogenesis was greatly stimulated by high levels of methylated sulfur compounds, and a methanogenic bacterium which is capable of growth on DMS was isolated and characterized. Results from experiments with endogenous levels (5 ..mu..M) of DMS in salt marsh sediment slurries, showed that sulfate reduction accounted for >80% of DMS metabolism, while methanogenesis accounted for <20%. However, DMS appears to contribute a significant (up to 30%) fraction to the total CH/sub 4/ produced in slurry assays.

Research Organization:
State Univ. of New York, Stony Brook (USA)
OSTI ID:
5964111
Country of Publication:
United States
Language:
English