DESULFONATRONOVIBRIO HYDYOGENOVORANS GEN-NOV, SP-NOV, AN ALKALIPHILIC, SULFATE-REDUCING BACTERIUM

A new alkaliphilic, sulfate-reducing bacterium, strain Z-7935(T) (T = type strain), was isolated from a soda-depositing lake, Lake Magadi in Kenya. This organism is a motile vibrio, which utilizes only hydrogen and formate as electron donors and sulfate, sulfite, and thiosulfate, but not sulfur, as electron accepters. Thiosulfate is dismutated. Str ain Z-7935(T) is an obligately sodium-dependent alkaliphile which grow s in sodium carbonate medium and does not grow at pH 7; the maximum pH for growth is more than pH 10, and the optimum pH is 9.5 to 9.7. The optimum NaCl concentration for growth is 3% (wt/vol). The optimum temp erature for growth is 37 degrees C. The G+C content of the DNA is 48.6 mol%. 16S ribosomal DNA sequence analysis revealed that strain Z-7935 (T) represents a new lineage with genus status in the delta subclass o f the Proteobacteria. The name Desulfonatronovibrio hydrogenovorans ge n. nov., sp. nov. is proposed for this organism; the type strain of D. hydrogenovorans is strain Z-7935 (= DSM 9292).