Microbacterium phosphatis sp. nov., an actinomycete isolated from a phosphate mine

Two Gram-staining-positive, non-motile and non-spore-forming bacterial strains, designated as 9H2^T and YDN13, were isolated from a phosphate mine in Yunnan Province, China. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strains 9H2^T and YDN13 belong to the genus Microbacterium. Results show that strains 9H2^T and YDN13 occupied a distinct position within the genus Microbacterium and showed the highest 16S rRNA gene sequence similarity of 97.6% with the type strains of Microbacterium thalassium CCTCC AB 2020140^T, followed by 97.5% with Microbacterium hydrocarboxydans DSM 16089^T and 97.3% with Microbacterium stercoris CCTCC AA 2018028^T. In the phylogenetic trees based on 16S rRNA gene sequences, strains 9H2^T and YDN13 were closely related to M. stercoris CCTCC AA 2018028^T and Microbacterium sediminicola YM 10-847^T. Strains 9H2^T and YDN13 showed the highest values of an orthologous average nucleotide identity (84%) and a digital DNA-DNA hybridization (49%) with M. stercoris CCTCC AA 2018028^T, followed by an orthologous average nucleotide identity of 76.0% and a digital DNA-DNA hybridization value of 17.9% with M. thalassium CCTCC AB 2020140^T. The respiratory menaquinones were MK-11, MK-12, MK-10 and MK-13. The major fatty acid profile contained anteiso-C_15 : 0, iso-C_16 : 0 and anteiso-C_17 : 0. The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, three unidentified phospholipids and one unidentified glycolipid. The whole-cell sugars included galactose and glucose. The peptidoglycan hydrolysate contained glutamate, glycine, ornithine and alanine. The DNA G+C contents were 71.1 mol%. Phenotypic, phylogenetic, chemotaxonomic and genomic analyses revealed that strains 9H2^T and YDN13 represent a novel species of Microbacterium, for which the name Microbacterium phosphatis sp. nov. was proposed. The type strain is 9H2^T (MCCC 1K08680^T=KCTC 59053^T=CGMCC 1.60061^T).