Sulfur Bacteria
Sulfur bacteria are prokaryotes that use reduced or oxidized sulfur compounds in their energy transformations. Reduced sulfur compounds, such as sulfide and elemental sulfur, can be used as electron donors for photosynthetic growth by anoxygenic phototrophic sulfur bacteria, or as energy and electron sources by colorless sulfur-oxidizing bacteria. In contrast, oxidized sulfur compounds, such as sulfate, can be used by sulfate-reducing bacteria as electron acceptors for the oxidation of organic matter. Sulfur-reducing bacteria also oxidize organic matter to obtain energy and reduce power, but they use zero-valent sulfur as an electron acceptor. The availability of sulfur compounds in an adequate redox status is consequently a requirement for each group of sulfur bacteria. In inland waters, typical environments where particular types of sulfur bacteria develop are the hypolimnia of stratified lakes, sediments of aquatic habitats, sulfide-rich spring sources (sulfureta), saline and soda lakes, extremely acidic waters, or ponds rich in organic matter. Sulfur bacteria are a metabolically and phylogenetically diverse group, which include taxa belonging to diverse phylogenetic branches among the Domains Bacteria and Archaea. Sulfur bacteria are critical mediators of redox transformations occurring within the biogeochemical sulfur cycle of the biosphere.
Keywords
Anoxic hypolimnionArchaeaBiogeochemical sulfur cycleColorless sulfur bacteriaHot springsPhototrophic sulfur bacteriaSalinesoda lakesSedimentsSulfateSulfate-reducing bacteriaSulfideSulfurSulfuretum