Sulfur-reducing bacteria are microorganisms able to reduce elemental sulfur (S0) to hydrogen sulfide (H2S). These microbes use inorganic sulfur compounds as electron acceptors to sustain several activities such as respiration, conserving energy and growth, in absence of oxygen. The final product of these processes, sulfide, has a considerable influence on the chemistry of the environment and, in addition, is used as electron donor for a large variety of microbial metabolisms. Several types of bacteria and many non-methanogenic archaea can reduce sulfur. Microbial sulfur reduction was already shown in early studies, which highlighted the first proof of S0 reduction in a vibrioid bacterium from mud, with sulfur as electron acceptor and H
2 as electron donor. The first pure cultured species of sulfur-reducing bacteria, Desulfuromonas acetoxidans, was discovered in 1976 and described by Pfennig Norbert and Biebel Hanno as an anaerobic sulfur-reducing and acetate-oxidizing bacterium, not able to reduce sulfate. Only few taxa are true sulfur-reducing bacteria, using sulfur reduction as the only or main catabolic reaction. Normally, they couple this reaction with the oxidation of acetate, succinate or other organic compounds. In general, sulfate-reducing bacteria are able to use both sulfate and elemental sulfur as electron acceptors. Thanks to its abundancy and thermodynamic stability, sulfate is the most studied electron acceptor for anaerobic respiration that involves sulfur compounds. Elemental sulfur, however, is very abundant and important, especially in deep-sea hydrothermal vents, hot springs and other extreme environments, making its isolation more difficult. Some bacteria – such as Proteus, Campylobacter, Pseudomonas and Salmonella – have the ability to reduce sulfur, but can also use oxygen and other terminal electron acceptors.
Acetivibrio clariflavus is an anaerobic bacterium from the genus Acetivibrio which has been isolated from sludge from a cellulose-degrading bioreactor in Japan.
Carboxydothermus is a genus of thermophilic, anaerobic bacteria from the family of Thermoanaerobacteraceae.
Carboxydothermus pertinax is a thermophilic and anaerobic bacterium from the genus of Carboxydothermus which has been isolated from a hot spring on the Kyushu Island in Japan.
Caldimicrobium is a genus of bacteria from the family of Thermodesulfobacteriaceae.
Caldimicrobium thiodismutans is a Gram-negative, thermophilic, rod-shaped, autotrophic and motile bacterium from the genus of Caldimicrobium which has been isolated from a hot spring in Nakabusa in Japan.
Caloranaerobacter is a Gram-negative, thermophilic, anaerobic and chemoorganotrophic bacterial genus from the family of Clostridiaceae.
Garciella is a Gram-positive, halotolerant, obligately anaerobic and moderately thermophilic bacterial genus from the family of Eubacteriaceae with one known species.
Microaerobacter is a thermophilic, microaerophilic and anaerobic genus of bacteria from the family of Bacillaceae with one known species. Microaerobacter geothermali has been isolated from a hot spring from Hammam Sidi, Nabeul, Tunisia.
Hippea maritima is a bacterium from the genus of Hippea which has been isolated from sediments from a hydrothermal vent from Matupi Harbour in Papua New Guinea.
Vulcanibacillus is a genus of bacteria from the family of Bacillaceae with one known species. Vulcanibacillus modesticaldus has been isolated from a hydrothermal vent from the Rainbow Vent Field.
Thermodesulfobium is a Gram-negative, strictly anaerobic, moderately thermophilic, non-spore-forming and non-motile genus of bacteria from the family of Thermodesulfobiaceae.
Thermodesulfobium narugense is a sulfate-reducing, strictly anaerobic and moderate thermophilic bacterium from the genus of Thermodesulfobium which has been isolated from a hot spring from Miyagi Prefecture in Japan. This microorganism is nonmotile, rod-shaped, Gram-negative and non-spore-forming.
Caldicoprobacter is a genus of bacteria from the family of Caldicoprobacteraceae.
Caldilinea is a genus of bacteria from the family of Caldilineaceae.
Thermanaerothrix is a bacteria genus from the family of Anaerolineaceae with one known species. Thermanaerothrix daxensis has been isolated from water from the Saint-Christophe spring in France.
Fontimonas is a Gram-negative genus of bacteria from the family of Nevskiaceae with one known species. Fontimonas thermophila has been isolated from a hot spring from the Hot Springs National Park in the United States.
Lebetimonas is a genus of bacteria from the family Nautiliaceae.
Ferrimonas kyonanensis is a facultatively anaerobic and mesophilic bacterium from the genus of Ferrimonas which has been isolated from the alimentary tract of a littleneck clam from the Tokyo Bay in Japan.
The Ignavibacteriales are an order of obligately anaerobic, non-photosynthetic bacteria that are closely related to the green sulfur bacteria.
