DESULFOHALOBIUM-RETBAENSE GEN-NOV, SP-NOV, A HALOPHILIC SULFATE-REDUCING BACTERIUM FROM SEDIMENTS OF A HYPERSALINE LAKE IN SENEGAL

Sulfate-reducing bacterial strain HR100 was isolated from sediments of Retba Lake, a pink hypersaline lake in Senegal. The cells were motile, nonsporulating, and rod shaped with polar flagella and incompletely oxidized a limited range of substrates to acetate and CO2. Acetate and vitamins were required for growth and could be replaced by Biotrypcase or yeast extract. Sulfate, sulfite, thiosulfate, and elemental sulfur were used as electron acceptors and were reduced to H2S. Growth occurred at pH values ranging from 5.5 to 8.0. The optimum temperature for growth was 37 to 40-degrees-C. NaCl and MgCl2 were required for growth; the optimum NaCl concentration was near 10%. The guanine-plus-cytosine content of the DNA was 57.1 +/- 0.2 mol%. On the basis of the morphological and physiological properties of this strain, we propose that it should be classified in a new genus, Desulfohalobium, which includes a single species, Desulfohalobium retbaense. The type strain is strain DSM 5692.