Proposal of Lysinibacillus boronitolerans gen. nov. sp. nov., and transfer of Bacillus fusiformis to Lysinibacillus fusiformis comb. nov. and Bacillus sphaericus to Lysinibacillus sphaericus comb. nov.

Abstract

Three strains of a spore-forming, Gram-positive, motile, rod-shaped and boron-tolerant bacterium were isolated from soil. The strains, designated 10aT, 11c and 12B, can tolerate 5 % (w/v) NaCl and up to 150 mM boron, but optimal growth was observed without addition of boron or NaCl in Luria–Bertani agar medium. The optimum temperature for growth was 37 °C (range 16–45 °C) and the optimum pH was 7.0–8.0 (range pH 5.5–9.5). A comparative analysis of the 16S rRNA gene sequence demonstrated that the isolated strains were closely related toBacillus fusiformisDSM 2898T(97.2 % similarity) andBacillus sphaericusDSM 28T(96.9 %). DNA–DNA relatedness was greater than 97 % among the isolated strains and 61.1 % withB. fusiformisDSM 2898Tand 43.2 % withB. sphaericusIAM 13420T. The phylogenetic and phenotypic analyses and DNA–DNA relatedness indicated that the three strains belong to the same species, that was characterized by a DNA G+C content of 36.5–37.9 mol%, MK-7 as the predominant menaquinone system and iso-C15 : 0(32 % of the total) as a major cellular fatty acid. In contrast to the type species of the genusBacillus, the strains contained peptidoglycan with lysine, aspartic acid, alanine and glutamic acid. Based on the distinctive peptidoglycan composition, phylogenetic analyses and physiology, the strains are assigned to a novel species within a new genus, for which the nameLysinibacillus boronitoleransgen. nov., sp. nov. is proposed. The type strain ofLysinibacillus boronitoleransis strain 10aT(=DSM 17140T=IAM 15262T=ATCC BAA-1146T). It is also proposed thatBacillus fusiformisandBacillus sphaericusbe transferred to this genus asLysinibacillus fusiformiscomb. nov. andLysinibacillus sphaericuscomb. nov., respectively.