Anoxybacillus mongoliensis sp. nov., a novel thermophilic proteinase producing bacterium isolated from alkaline hot spring, central Mongolia

A Gram reaction positive, spore-forming, facultative anaerobic bacterium belonging to the Phylum Firmicutes, was isolated from alkaline hot (80 degrees C, pH 9.8 spring Tsenher, central Mongolia. The cells were rod shaped, feebly motile, peritrichously flagellated. Strain T4 was moderately thermophilic with optimum growth at 60 degrees C. Maximum temperature for growth was between 70 and 75 degrees C; minimum temperature for growth was between 35 and 30 degrees C. Alkalitolerant, optimum pH for growth was 8.0; minimum pH for growth was between 5.0 and 5.5 and maximum was between 10.5 and 10.8. The growth was observed at NaCl concentrations of 0-5% (w/v) with the optimum at 0.2-0.5%. No growth was observed at 6% NaCl (w/v). Aerobically, the strain utilized proteinaceous substrates, organic acids and a range of carbohydrates including glucose, ribose, sucrose and xylose as well. Anaerobically, only glucose and sucrose were utilized. Strain T4T produced thermostable alkaline subtilisin-like serine proteinase. The G + C content was 44.2 mol. % (td). On the basis of 16S rRNA gene sequence similarity strain T4(T) was shown to be closely related to the members of the genus Anoxybacillus (family Bacillaceae, class "Bacilli"). DNA-DNA hybridization data revealed that strain T4T had only 38% relatedness to A. flavithermus and 28% relatedness to A. pushchinoensis. Based on its morphology, physiology, phylogenetic relationship and its low DNA-DNA relatedness values with validly published species of Anoxybacillus, it is proposed that strain T4T represents a novel species Anoxybacillus mongoliensis sp. nov., with the type strain T4(T) (=DSM 19169 = VKM 2407).