Microbacterium helvum sp. nov., a novel actinobacterium isolated from cow dung

A Gram-positive, aerobic, non-motile, non-spore-forming, short rod-shaped strain, NEAU-LLC^T, was isolated from cow dung in Shangzhi City, Heilongjiang Province, Northeast China and identified by a polyphasic taxonomic study. Colonies was light yellow, round, with entire margin. Strain NEAU-LLC^T was grown at 15-45 ℃ and pH 6.0-10.0. NaCl concentration ranged from 0 to 5% (W/V). The 16S rRNA gene sequence of NEAU-LLC^T showed the high similarities with Microbacterium kyungheense JCM 18735^T (98.5%), Microbacterium trichothecenolyticum JCM 1358^T (98.3%) and Microbacterium jejuense JCM 18734^T (98.2%). The whole-cell sugars were glucose, rhamnose and ribose. The menaquinones contained MK-12 and MK-13. Ornithine, glutamic acid, lysine and a small amount of alanine and glycine were the amino acids in the hydrolyzed products of the cell wall. The major fatty acids were iso-C_16:0, iso-C_18:0, anteiso-C_15:0 and anteiso-C_17:0. The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and an unidentified glycolipid. The genome of NEAU-LLC^T was 4,369,375 bp and G + C content is 70.28 mol%. A combination of DNA-DNA hybridization result and some phenotypic characteristics demonstrated that strain NEAU-LLC^T could be distinguished from its closely related strains. Therefore, the strain NEAU-LLC^T was considered to represent a novel species, which was named Microbacterium helvum sp. (Type strain NEAU-LLC^T = CCTCC AA 2018026^T = JCM 32661^T).