Desulfurellaceae
The Desulfurellaceae form a family within the Deltaproteobacteria and are the some member of the order Desulfurellales. Like all Proteobacteria, the gram- negative species. The cells are rod-shaped and usually movable by a single polar flagellum. It is anaerobic, chemoorganotrophic or chemolithoautotrophically bacteria. The types of Desulfurellaceae are Schwefelreduzierer, in the metabolism convert elemental sulfur to hydrogen sulfide. Another feature is the absence of cytochromes, although a respiratory metabolism is performed.
Ecology
All species are thermophilic, the best growth occurs at temperatures between 50 and 60 ° C. Habitats are seawater and geothermal heated, sulfur-containing freshwater. By the reduction of sulfur, or thiosulfate polysulfides to hydrogen sulfide, they are important for the sulfur cycle.
Metabolism
The types of Desulfurellaceae among the sulfur-reducing bacteria, which are also referred to as Schwefelatmer. It is in an anaerobic respiratory metabolism. Instead of oxygen in aerobic respiration are elemental sulfur or polysulfides as an electron acceptor. Electron donors are simple organic compounds, they are completely oxidized to carbon dioxide by the citric acid cycle. The sulfur compounds are reduced to sulphide and hydrogen sulphide. Desulfurella propionica also reduces thiosulfate.
This pathway is largely the Desulfurikation, except that only elemental sulfur ( thiosulfate and polysulfides also ) is used. In Desulfurikation, also referred to as dissimilatory sulfate - reducing primarily serves sulfate, in various types and sulfite, thiosulfite and elemental sulfur as the acceptor. The final product is also hydrogen sulfide. In contrast to the sulfate -reducing bacteria ( engl.: Sulfate -Reducing Prokaryotes ) one thus speaks at the Desulfurellaceae of sulfur-reducing bacteria (English: Sulfur -Reducing Prokaryotes ). The prefix desulfur refers to the elemental sulfur (sulfur ). Desulfurella multipotens is chemolithoautotrophically, it needs to grow only CO2, H2 and elemental sulfur. If available, it uses but also organic compounds such as acetate, pyruvate, butyrate, and saturated fatty acids. The organic compounds used as electron donors are usually completely oxidized to CO2.
Hippea maritima is chemolithotroph, it uses H2 and sulfur, but needs organic compounds as electron donors and carbon source. Utilized organic compounds are, for example, Acetate, pyruvate and saturated fatty acids.
Some types also have the ability to ferment as Energiestoffwechselweg.
System
The family consists of the following genera and species:
- Desulfurella Bonch - Osmolovskaya et al. 1993 Desulfurella acetivorans Bonch - Osmolovskaya et al. 1993
- Desulfurella kamchatkensis Miroshnichenko et al. 1998
- Desulfurella multipotens Miroshnichenko et al. 1996
- Desulfurella propionica Miroshnichenko et al. 1998
- Hippea maritima Miroshnichenko et al. 1999