Neobacillus endophyticus sp. nov., an endophytic bacterium isolated from Selaginella involvens roots.

ABSTRACT

A Gram-stain-positive, facultatively anaerobic, rod-shaped, endospore-forming, oxidase-positive, and catalase-negative strain designated as BRMEA1T was isolated from the surface-sterilized Selaginella involvens roots. Growth of strain BRMEA1T was found to occur at pH 6.0-8.0 (optimum, pH 7.0), 15-50 °C (optimum, 25-30 °C) and in the absence of NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain BRMEA1T formed a lineage within the genus Neobacillus (family Bacillaceae) and showed the highest sequence similarity to Neobacillus drentensis DSM 15600T (98.3 %) and Neobacillus fumarioli KCTC 13885T (98.2 %), and less than 98.2 % 16S rRNA gene sequence similarity to the other members of the genus Neobacillus. Whole-genome analysis of strain BRMEA1T comprised a circular chromosome (5 632 809 bp in size) with 38.5 mol% G+C content. Digital DNA-DNA hybridization analyses revealed that strain BRMEA1T showed 20.5 and 22.0% genomic DNA relatedness with the closest species, N. drentensis DSM 15600T and N. fumarioli KCTC 13885T, respectively. The whole-genome sequence of strain BRMEA1T showed the presence of 11 specific conserved signature indels for the genus Neobacillus. The major cellular fatty acids (>10 %) of strain BRMEA1T were found to be iso-C15  0 and anteiso-C15  0, while the major polar lipids were found to be diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. Polyphasic analysis results revealed that BRMEA1T represents a novel species of the genus Neobacillus, with the proposed name Neobacillus endophyticus sp. nov. The type strain is BRMEA1T (=KCTC 43208T=CCTCC AB 2020071T).