Bacillus rhizosphaerae sp. nov., an novel diazotrophic bacterium isolated from sugarcane rhizosphere soil

Abstract

A Gram-positive, non-pigmented, rod-shaped, diazotrophic bacterial strain, designated SC-N012 T, was isolated from rhizosphere soil of sugarcane and was subjected to a polyphasic taxonomic study. The strain exhibited phenotypic properties that included chemotaxonomic characteristics consistent with its classification in the genus Bacillus. Sequence analysis of the 16S rRNA gene of SC-N012 T revealed the closest match (98.9% pair wise similarity) with Bacillus clausii DSM 8716 T. However, DNA-DNA hybridization experiments indicated low levels of genomic relatedness (32%) with this strain. The major components of the fatty acid profile are iso-C 15:0, anteiso-C 15:0, iso-C 17:0 and anteiso-C 17:0. The diagnostic cell-wall diamino acid was meso-diaminopimelic acid. The G+C content of the genomic DNA is 43.0 mol%. The lipids present in strain SC-N012 T are diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol and two unknown phospholipids. Their predominant respiratory quinone was MK-7. Studies of DNA-DNA relatedness, morphological, physiological and chemotaxonomic analyses and phylogenetic data based on 16S rRNA gene sequencing allowed strain SC-N012 T to be described as members of novel species of the genus Bacillus, for which the name Bacillus rhizosphaerae sp. nov. is proposed. The type strain is SC-N012 T (=DSM 21911 T = NCCB 100267 T).