Sulfate-reducing bacteria
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Sulfate-reducing bacteria comprise several groups of bacteria that use sulfate as an oxidizing agent, reducing it to sulfide. Most can also use oxidized sulfur compounds such as sulfite and thiosulfate, or elemental sulfur. This is called dissimilatory sulfur metabolism, since it is not assimilated into any organic compounds. Sulfate-reducing bacteria have been considered as a possible way to deal with acid mine waters other bacteria produce.
[edit] Phylogeny
The sulfate-reducing bacteria have been treated as phenotypic group, together with the other sulfur-reducing bacteria, for identification purposes. They are found in several different phylogenetic lines. Three lines are included among the Proteobacteria, all in the delta subgroup:
A fourth group including thermophiles is given its own phylum, the Thermodesulfobacteria. The remaining sulfate-reducers are included with other bacteria among the Nitrospirae and the gram-positive Peptococcaceae - for instance Thermodesulfovibrio and Desulfotomaculum, respectively. There is also a single genus of Archaea capable of sulfate reduction, Archaeoglobus.
[edit] Environmental markers
The rotten egg odor of hydrogen sulfide is often a marker for the presence of sulfate-reducing bacteria in nature, according to Betsey Dexter Dyer's Field Guide to Bacteria. Sulfate-reducing bacteria are responsible for the sulfur odor of salt marshes and mud flats, and also for some of the trace amounts of sulfur in intestinal gas that causes the bad smell.
Sulfate-reducing bacteria slowly ferment tough-to-digest materials rich in cellulose in anaerobic environments, Dyer writes. Rather than breathing oxygen, they "breathe" sulfate that comes from seawater, sediment or water rich in decaying organic material.
[edit] References
Dexter Dyer, Betsey (2003). A Field Guide to Bacteria. Ithaca and London: Comstock Publishing Associates/Cornell University Press.
