A Moderately Boron-tolerant Candidatus Novel Soil Bacterium Lysinibacillus Pakistanensis Sp. Nov. Cand., Isolated from Soybean (glycine Max L.) Rhizosphere

A Gram-positive, motile, rod-shaped, endospore-forming and moderately boron (B) tolerant novel candidatus strain, designated as NCCP-54, was isolated from rhizospheric soil of soybean (Glycine max L.) sampled from the experimental area of Research Farm, PMAS Arid Agriculture University, Rawalpindi, Pakistan. To delineate its taxonomic position, the strain was subject to polyphasic characterization. Cells of the strain NCCP-54 can grow at 10-45C (optimum at 28C) at pH ranges of 6.5-9.0 (optimum at pH 7.0) and in 0-6% NaCl (w/v) in tryptic soya agar medium. It can also tolerate 150 mM boric acid in agar medium; however, optimum growth occurs in the absence of boric acid. Based on 16S rRNA gene sequence analysis, strain NCCP-54 showed highest similarity to Lysinibacillus xylanilyticus KCTC13423 (99.1%), Lysinibacillus fusiformis KCTC3454 (98.5%), Lysinibacillus boronitolerans KCTC13709 (98.4%), Lysinibacillus parviboronicapiens KCTC13154 (97.8%), and Lysinibacillus sphaericus KCTC3346 (97.5%) and less than 97% with other closely related taxa. The level of DNA–DNA relatedness between strain NCCP-54 and the type strains of genus Lysinibacillus was <27 %. Strain was also studied chemotaxonomically. Whole-cell peptidoglycan of strain NCCP-54 contained meso-diaminopimelic acid (meso-Dpm) as major diagnostic amino acids instead of lysine-aspartate (Lys-Asp) which is the characteristic of the genus Lysinibacillus. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. MK-7 was the predominant menaquinones. The major cellular fatty acids were iso-C15:0 (30.29%) followed by iso-C16:0 (25.59%) and C16:1w7calcohol (16.24%). The G + C contents of the strain is 37 mol%. The chemotaxonomic characteristics of the candidatus novel strain matched those described for the members of genus Lysinibacillus except diagnostic amino acids contained in peptidoglycans. Phenotypic and phylogenetic analyses thus indicate that strain NCCP-54 may represent a novel candidatus status of species in the genus Lysinibacillus, for which the name Lysinibacillus pakistanensis is proposed. The type strain is NCCP-54 (DSMZ 24784 = KCTC= 13795). The DDBJ/EMBL/GenBank accession number of the 16S rRNA gene sequence of strain NCCP-54 is AB558495.