Bacillus catenulatus sp. nov., an alkalitolerant bacterium isolated from a soda lake

Two novel (18Cᵀ and 6C) 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, strains 18Cᵀ and 6C were identified as belonging to the class Firmibacteria, and were most closely related to Bacillus cohnii KCTC 3572ᵀ (99.3 and 99.9%, respectively), Bacillus zhanjiangensis KCTC 13713ᵀ (97.4 and 98.0%, respectively), Bacillus halmapalus LMG 17950ᵀ (97.0 and 97.6%, respectively) and other members in the genus Bacillus (<97.0%). However, the DNA–DNA relatedness between 18Cᵀ and 6C and B. cohnii KCTC 3572ᵀ (49.6 ± 0.9 and 51.6 ± 0.7, respectively), B. zhanjiangensis KCTC 13713ᵀ (42.9 ± 0.8 and 47.1 ± 0.3, respectively) and B. halmapalus LMG 17950ᵀ (39.9 ± 0.8 and 40.8 ± 0.3, respectively) indicated that the novel strains were distantly related to these strains. Further, the high 16S rRNA gene sequence similarity (100%) and DNA–DNA relatedness (90 ± 5%) suggested that strains 18Cᵀ and 6C were members of a genomospecies. The strains grew optimally at a pH of 7.5 with 2–3% (w/v) NaCl and temperature of 37 °C. Strains 18Cᵀ and 6C were catalase and oxidase negative. The cell wall of strain 18Cᵀ contained meso-diaminopimelic acid as the diagnostic diamino acid, which was in contrast with its nearest neighbour B. cohnii KCTC 3572ᵀ, which contained ornithine and aspartic acid. Polar lipids include diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), an unknown phospholipid (PL) and three unknown lipids (L1-3). The predominant isoprenoid quinone was MK-7. iso-C₁₅:₀ (32.5%) was the predominant fatty acid and significant proportions of anteiso-C₁₅:₀ (19.5%), C₁₆:₀ (11.5%), iso-C₁₇:₀ (9.5%) and anteiso-C₁₇:₀ (6.3%) were also detected. The DNA G + C content of strains 18Cᵀ and 6C were 39.3 and 39.2 mol%, respectively. The results of molecular, biochemical and chemotaxonomic tests showed a clear differentiation of strains 18Cᵀ and 6C from all other members of the genus Bacillus, for which the name Bacillus catenulatus sp. nov. is proposed. The type strain is 18Cᵀ (=KCTC 33781ᵀ = CGMCC 1.15475ᵀ).