Lysinibacillus varians sp. nov., an endospore-forming bacterium with a filament-to-rod cell cycle.

Abstract

Six Gram-stain-positive, motile, filamentous and/or rod-shaped, spherical spore-forming bacteria (strains GY32(T), L31, F01, F03, F06 and F07) showing polybrominated diphenyl ether transformation were investigated to determine their taxonomic status. After spore germination, these organisms could grow more than one hundred microns long as intact single cells and then divide into rod cells and form endospores in 33 h. The cell-wall peptidoglycan of these strains was type A4α, the predominant menaquinone was MK-7 and the major fatty acids were iso-C(16:0), iso-C(15:0) and C(16:1)ω7C. Diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine were detected in the polar lipid profile. Analysis of the 16S rRNA gene sequences indicated that these strains should be placed in the genus Lysinibacillus and they were most closely related to Lysinibacillus sphaericus DSM 28(T) (99% 16S rRNA gene sequence similarity). The gyrB sequence similarity and DNA-DNA relatedness between strain GY32(T) and L. sphaericus JCM 2502(T) were 81% and 52%, respectively. The G+C content of the genomic DNA of strain GY32(T) was 43.2 mol%. In addition, strain GY32(T) showed differences in nitrate reduction, starch and gelatin hydrolysis, carbon resource utilization and cell morphology. The phylogenetic distance from its closest relative measured by DNA-DNA relatedness and DNA G+C content, and its phenotypic properties demonstrated that strain GY32(T) represents a novel species of the genus Lysinibacillus, for which the name Lysinibacillus varians sp. nov. is proposed. The type strain is GY32(T) ( = NBRC 109424(T) = CGMCC 1.12212(T) = CCTCC M 2011307(T)).