Thiopseudomonas denitrificans gen. nov., sp. nov., isolated from anaerobic activated sludge.

A Gram-staining-negative, rod-shaped, motile and facultatively anaerobic bacterial strain, designated X2(T), was isolated from the sludge of an anaerobic, denitrifying, sulfide-removal bioreactor, and found to oxidize sulfide anaerobically with nitrate as electron acceptor. The strain grew at salinities of 0-3% (w/v) NaCl (optimum, 0-1%). Growth occurred at pH 6.0-10.0 (optimum, pH 8.0) and 10-37 °C (optimum, 30 °C). The genomic DNA G+C content was 59 mol%. Q-8 and Q-9 were detected as the respiratory quinones. The major fatty acids (>10 %) were C16:1ω7c and/or C16: 1ω6c, C18: 1ω7c and C16:0. The polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and one unidentified phospholipid. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain X2(T) formed a novel clade within the family Pseudomonadaceae, with the highest sequence similarity to Pseudomonas caeni KCTC 22292(T) (93.5%). On the basis of phenotypic, chemotaxonomic and phylogenetic characteristics, it is proposed that this strain represents novel genus and species within the family Pseudomonadaceae, for which the name Thiopseudomonas denitrificans gen. nov., sp. nov. is proposed. The type strain is X2(T) ( =CCTCC M 2013362(T) =DSM 28679(T) = KCTC 42076(T)).