Desulfuribacillus stibiiarsenatis sp nov., an obligately anaerobic, dissimilatory antimonate- and arsenate-reducing bacterium isolated from anoxic sediments, and emended description of the genus Desulfuribacillus

A novel anaerobic, Gram-stain-negative, endospore-forming bacterium, designated strain MLFW-2(T),was isolated from anoxic sediments collected from the drainage area of a geothermal spring near Mono Lake, CA, USA. Optimal growth was achieved at 34 degrees C and pH 8.25-8.50 in medium containing 0.75% (w/v) NaCl. Catalase, but not oxidase, was produced. Strain MLFW-2(T) was an obligate anaerobe capable of respiring with nitrate, nitrite, DMSO, arsenate, antimonate, selenate and selenite as terminal electron acceptors. Lactate, pyruvate, formate and H-2 could serve as electron donors to support growth. The isolate was incapable of fermentation. The predominant fatty acids were C-16:0, C-16:1 omega 9c, C-16:1 omega 7c, C-18:1 omega 9c and C-18:1 omega 7c. The major polar lipids were phosphatidylglycerol and phosphatidylethanolamine. The only isoprenoid quinone detected was menaquinone 7 (MK-7). The DNA G+C content was 38.2 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence demonstrated that strain MLFW-2(T) was a member of the order Bacillales and was most closely related to Desulfuribacillus alkaliarsenatis AHT28(T) (93.9% similarity). On the basis of phenotypic and phylogenomic evidence, strain MLFW-2(T) represents a novel species of the genus Desulfuribacillus, for which the name Desulfuribacillus stibiiarsenatis sp. nov. is proposed. The type strain is MLFW-2(T) (= DSM 28709(T) = JCM 30866(T)). An emended description of the genus Desulfuribacillus is also provided.