Sulfate-reducing prokaryotes (SRPs)
16S rRNA-based phylogenetic consensus tree showing the affiliation of all named SRPs within the class "Deltaproteobacteria". SRPs are shown in bold face type. The bar indicates 10% estimated sequence divergence. |
SRPs are ubiquitous, inhabiting mainly anoxic zones but also the oxic/anoxic interface of various environments, and constitute an essential biotic component of the global sulfur cycle. From the viewpoint of modern rRNA-based taxonomy SRPs form a rather heterogenous group. However, their general geobiological importance legitimates grouping in a functional microbial guild. The unifying physiological trait of these microorganisms is their ability to use sulfate dissimilatively as terminal electron acceptor coupled with the generation of energy. This unique geobiological process is called dissimilatory sulfate reduction or anaerobic sulfate respiration and is exclusively restricted to the prokaryotic domains of life. |
Dissimilatory sulfate reduction is a very ancient process. Earliest geological records of microbial sulfate reduction date back in the early Archaean era, more than ~3.47 billion years ago (Shen et al. 2001, Nature).
All sulfate-reducing species that could be cultivated so far belong either to one of the four bacterial phyla Proteobacteria, Firmicutes, Nitrospirae, or Thermodesulfobacteria or to the archaeal phylum Euryarchaeota (see the latest  taxonomic outline of Bergey`s Manual of Systematic Bacteriology).
Taxonomy of SRPs from the domain down to the family level
Domain Bacteria
Phylum Proteobacteria
Class "Deltaproteobacteria"
Order "Desulfovibrionales"
Family "Desulfovibrionaceae"
Family "Desulfomicrobiaceae"
Family "Desulfohalobiaceae"
Family "Desulfonatronumaceae"
Order "Desulfobacterales"
Family "Desulfobacteraceae"
Family "Desulfobulbaceae"
Order "Syntrophobacterales"
Family "Syntrophobacteraceae"
Phylum Firmicutes
Class "Clostridia"
Order Clostridiales
Family "Peptococcaceae"
Phylum Nitrospirae
Class "Nitrospira"
Order "Nitrospirales"
Family "Nitrospiraceae"
Phylum Thermodesulfobacteria
Class Thermodesulfobacteria
Order Thermodesulfobacteriales
Family Thermodesulfobacteriaceae
Domain Archaea
Phylum Euryarchaeota
Class Archaeoglobi
Order Archaeoglobales
Family Archaeoglobaceae
Links
PhyloChips
Dissimilatory sulfite reductase as a marker for phylogenetic and ecological studies of sulfate-reducing prokaryotes [PDF]
Investigated by: Alexander Loy, Ingo Starke
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