Syntrophobacterales
The Syntrophobacterales form an order of mostly sulfate-reducing bacteria within the Deltaproteobacteria. One speaks of the Desulfurikation or sulfate reduction. The species name the preceding syllable desulfo - stands for this pathway. However, many species of this order additionally use when there is insufficient sulfur compounds are present, the fermentation as an energy -producing pathway. Some genera or species are not capable of Desulfurikation, then the fermentation is the only pathway for energy production. This is the case for example with Syntrophus. The order consists of three families: Syntrophobacteraceae, Syntrophorhabdaceae and Syntrophaceae.
Ecology and features
Some members live syntroph: The growth is made possible by the exchange of certain metabolic products with other bacteria. So Syntrophobacter oxidized propionate, there arises acetate, CO2 and H2. For the growth of a formate and hydrogen consuming organisms, such as Desulfovibrio is required because a small Syntrophobacter hydrogen and formate in the area required to insert the oxidizing energiegewinnend. Bacteria which produce by metabolism acetate as the only organic end product are referred to as acetogenic bacteria. A syntrophic association with methagonen archaea ( methanogens ) may also exist.
All kinds of Syntrophobacterales are strictly anaerobic. Some species are movable by flagella, usually a polar flagellum is present. Some species possess flagella only in the early growth stage of the crops, such as Syntrophus buswellii and Syntrophobacter pfennigii. The cells are mostly rod -shaped. Thermodesulforhabdus norvegica and Desulfacinum infernum (Family Syntrophobacteraceae ) are thermophilic, their growth rates are highest at temperatures around 60 ° C. All other species are mesophilic. Habitats of all species of this order are anoxic (no oxygen-containing ) fresh or sea water.
Desulfurikation
In the sulfate form of the breathing as energy metabolism, sulfate, thiosulfate or sulfite are used as electron acceptors, oxygen is not as in the aerobic respiration. The corresponding sulfur compounds are reduced here to hydrogen sulfide. Simple organic compounds, such as pyruvate, butyrate, ethanol, lactate, and serve as electron donors and carbon source, they are oxidized and assimilated. Syntrophobacter (Family Syntrophaceae ) Syntrophus and Ella Smith (Family Syntrophobacteraceae ) oxidize the organic matter is not complete, the product is acetate. All other species oxidize the organic matter completely to carbon dioxide.
Sulfate-reducing bacteria are also called Sulfate or Sulfatatmer. In English we find the names sulfate reducing bacteria (SRB ), sulfates at inclusion and sulfate-reducing archaea reducing prokaryotes (SRP ).
Other Sulfate- represented in the orders Desulfobacterales and Desulfovibrionales within the delta Proteobacteria. Representatives of Desulfuromonadales and Desulfurellaceae, also classified in the delta proteobacteria are called sulfur-reducing bacteria, they do not use sulfate, but mainly elemental sulfur ( or thiosulfate ) as electron acceptor. Furthermore, the Desulfurikation ( genus Desulfotomaculum ) occurs in the phylum Thermodesulfobacteria and in the order Clostridiales the Department Firmicutes. Also in the Archaea domain, there are Desulfurizierer, such as the genus Archaeglobus.
System
This order consists of the following families and genera:
- Syntrophobacteraceae Küver et al. 2006 Desulfacinum Rees et al. 1995 emend. Sievert and Küver 2000
- Desulfatimicrobium Azabou S et al
- Desulfoglaeba Davidova et al. 2006
- Oude Elferink Desulforhabdus et al. 1997
- Desulfosoma Baena et al. 2011
- Desulfovirga Tanaka et al. 2000
- Syntrophobacter Boone & Bryant 1984
- Thermodesulforhabdus Beeder et al. 1996
- Syntrophaceae Küver et al. 2006 Oude Elferink Desulfobacca et al. 1999
- Desulfomonile DeWeerd et al. 1991
- Smith Ella Liu et al. 1999
- Syntrophus Mountfort et al. 1984
- Syntrophorhabdaceae Qiu et al. 2008 Syntrophorhabdus Qiu et al. 2008