Syntrophobacterales
| Syntrophobacterales | ||||||||
|---|---|---|---|---|---|---|---|---|
| Systematics | ||||||||
|
||||||||
| Scientific name | ||||||||
| Syntrophobacterales | ||||||||
| Kuever et al. 2006 |
The Syntrophobacterales form an order of mostly sulphate-reducing bacteria within the Deltaproteobacteria . One speaks of desulfurication or sulfate reduction. The syllable Desulfo- preceding the species name stands for this metabolic pathway. However, many species of this order also use fermentation as an energy-producing metabolic pathway if there are not enough sulfur compounds available . Some genera or species are not capable of desulfurization; fermentation is then the only metabolic pathway for energy production. This is e.g. B. the case with Syntrophus . The order consists of three families: Syntrophobacteraceae , Syntrophorhabdaceae and Syntrophaceae .
Ecology and characteristics
Some members live syntrophically : growth is made possible by the exchange of certain metabolic products with other bacteria. Syntrophobacter oxidizes propionate , producing acetate, CO 2 and H 2 . An organism that consumes hydrogen and formate , e.g. B. Desulfovibrio required because Syntrophobacter needs a low hydrogen and formate content in the environment in order to use the oxidation to generate energy. Bacteria which metabolize acetate as the only organic end product are called acetogenic bacteria. A syntrophic association with methagon archaea ( methane producers ) can also exist.
All types of Syntrophobacterales are strictly anaerobic. Some species are motile by flagella , mostly a polar flagella is present. Some species have flagella only in the early growth stage of cultures, e.g. B. Syntrophus buswellii and Syntrophobacter pfennigii . The cells are usually rod-shaped. Thermodesulforhabdus norvegica and Desulfacinum infernum (family Syntrophobacteraceae) are thermophilic , their growth rates are highest at temperatures around 60 ° C. All other genus are mesophilic. Habitats of all species of this order are anoxic (no oxygen-containing) fresh or marine water.
Desulfurication
In sulphate respiration as a form of energy metabolism , sulphate , thiosulphate or sulphite serve as electron acceptors , not oxygen as in aerobic respiration. The corresponding sulfur compounds are reduced to hydrogen sulfide. Simple organic compounds such as B. pyruvate , butyrate , ethanol and lactate serve as electron donors and carbon source, they are oxidized or assimilated. Syntrophobacter (family Syntrophaceae ), Syntrophus and Smithella (family Syntrophobacteraceae ) do not completely oxidize the organic matter, the product is acetate . All other types completely oxidize the organic matter to carbon dioxide .
Sulphate-reducing bacteria are also known as desulphuricants or sulphate breathers. In English one finds the terms sulfate reducing bacteria (SRB), when including sulfate reducing archaea, sulfate reducing prokaryotes (SRP).
Further Desulfurikanten are represented in the orders Desulfobacterales and Desulfovibrionales within the Deltaproteobacteria. Representatives of the Desulfuromonadales and Desulfurellaceae , also classified under the Deltaproteobacteria, are referred to as sulfur-reducing bacteria; they do not use sulfate, but mainly elemental sulfur (or thiosulfate) as an electron acceptor. Furthermore, the desulfurication occurs in the Phylum Thermodesulfobacteria and in the order Clostridiales of the Firmicutes department (genus Desulfotomaculum ). Also in the domain Archaea there Desulfurizierer such. B. the genus Archaeglobus .
Systematics
This regulation consists of the following families and genera (as of November 30, 2019):
-
Syntrophobacteraceae Kuever et al. 2006
- Desulfacinum Rees et al. 1995 emend. Sievert and Kuever 2000
- Desulfoglaeba Davidova et al. 2006
- Desulforhabdus Oude Elferink et al. 1997
- Desulfosoma Baena et al. 2011
- Desulfovirga Tanaka et al. 2000
- Syntrophobacter Boone & Bryant 1984
- Thermodesulforhabdus Beeder et al. 1996
-
Syntrophaceae Kuever et al. 2006
- Desulfobacca Oude Elferink et al. 1999
- Desulfomonile DeWeerd et al. 1991
- Smithella Liu et al. 1999
- Syntrophus Mountfort et al. 1984
swell
literature
- Michael T. Madigan, John M. Martinko, Jack Parker: Brock - Microbiology . 11th edition. Pearson Studium, Munich 2006, ISBN 3-8274-0566-1
- George M. Garrity: Bergey's manual of systematic bacteriology . 2nd Edition. Springer, New York, 2005, Vol. 2: The Proteobacteria Part C: The Alpha-, Beta-, Delta-, and Epsilonproteabacteria ISBN 0-387-24145-0