Bacillus alcaliphilum sp. nov., a bacterium isolated from a soda lake

Abstract

Two novel (14B^T and 7B) Gram-stain-positive, rod-shaped, motile and endospore-forming bacterial strains were isolated from Lonar soda lake, India. Based on 16S rRNA gene sequence analysis, the strains 14B^T and 7B were identified as belonging to the class Firmibacteria and were most closely related to Bacillus halodurans LMG 7121^T (99.7 and 99.8%, respectively), Bacillus okuhidensis LMG 22468^T (99.1 and 99.2%, respectively) and other members in the genus Bacillus (<97.0%). However, the DNA–DNA relatedness studies indicated that the strains 14B^T and 7B were distantly related to B. halodurans LMG 7121^T (49.1 ± 0.6 and 45.7 ± 0.6, respectively) and B. okuhidensis LMG 22468^T (40.9 ± 0.9 and 42.1 ± 0.5, respectively). The high 16S rRNA gene sequence similarity (99.9%) and DNA–DNA relatedness (88 ± 9) indicated that strains 14B^T and 7B were members of a single species. The strains grew optimally at a pH of 9.0–9.5 with 2–5% (w/v) NaCl and temperature of 37 °C. Strains 14B^T and 7B were catalase positive and oxydase negative. The cell wall of strain 14B^T contained meso-diaminopimelic acid as the diagnostic diamino acid. Polar lipids include diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), an unknown aminophospholipid (APL1) and three unknown lipids (L1–3). The predominant isoprenoid quinone is MK-7. anteiso-C_15:0 (30.8%) was the predominant fatty acid, and significant proportions of iso-C_15:0 (24.9%), iso-C_16:0 (17.9%) and anteiso-C_17:0 (12.3%) were also detected in strains 14B^T and 7B. The DNA G+C content of strains 14B^T and 7B was 41.6 and 41.3 mol%, respectively. The results of molecular, physiological and biochemical tests allowed a clear differentiation of strains 14B^T and 7B from all other members of the genus Bacillus, for which the name Bacillus alcaliphilum sp. nov. is proposed. The type strain is 14B^T (=KCTC 33777^T = CGMCC 1.15474^T).

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