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-LLCT, 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-LLCT was grown at 15-45 celcius and pH 6.0-10.0. NaCl concentration ranged from 0 to 5% (W/V). The 16S rRNA gene sequence of NEAU-LLCT 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-LLCT 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-LLCT could be distinguished from its closely related strains. Therefore, the strain NEAU-LLCT was considered to represent a novel species, which was named Microbacterium helvum sp. (Type strain NEAU-LLCT = CCTCC AA 2018026(T) = JCM 32661(T)).

Automated summary

NEAU-LLCT strain, isolated from cow dung in Northeast China, represents a novel species named Microbacterium helvum sp. The strain shows distinct characteristics from closely related strains in terms of growth conditions, gene sequences, and biochemical properties. This conclusion was supported by DNA-DNA hybridization and phenotypic analysis.