Microbacterium songi sp. nov., Microbacterium hanjuni sp. nov. and Microbacterium shimangi sp. nov., three novel salt-tolerant bacteria isolated from plateau voles (Neodon fuscus)

Six novel bacterial strains, designated P01ᵀ, P02, P04ᵀ, P05, P06ᵀ and P07, were isolated from the intestinal contents of the Neodon fuscus collected from the Qinghai-Tibet Plateau, PR China. Cells were aerobic, non-motile, Gram-stain-positive, catalase-positive, oxidase-positive and rod-shaped. Strains P01ᵀ, P04ᵀ and P06ᵀ can grow at 4–37°C and tolerate 10.0% (w/v) NaCl. Phylogenetic and phylogenomic analyses based on the 16S rRNA gene sequences and core genes indicated that the three strain pairs (P01 T /P02, P04 T /P05 and P06 T /P07) were closely related to members of the genus Microbacterium , forming separate clades adjacent to Microbacterium hatanonis JCM 14558 T , Microbacterium rhizomatis JCM 30598 T and other Microbacterium strains. The digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) values between each strain (P01ᵀ, P04ᵀ and P06ᵀ) and the type strains of their closest relatives were all below the established species delineation thresholds (70% for dDDH and 95–96% for ANI). The major cellular fatty acids of all six strains were anteiso-C 15:0 and anteiso-C 17:0 . All novel type strains shared diphosphatidylglycerol, phosphatidylglycerol and one or two unidentified GLs as their predominant polar lipids. The peptidoglycan amino acids consisted of alanine, glutamic acid, glycine and ornithine. Menaquinones identified in these strains were MK-9, MK-11 and MK-13. In terms of cell-wall sugars, as determined by TLC, rhamnose, ribose, glucose and galactose were common to all three strains; additionally, mannose was detected in P04ᵀ, and both mannose and xylose were present in P06ᵀ. All these analyses concluded that these six strains represent three novel members of the genus Microbacterium , for which the names Microbacterium songi sp. nov., Microbacterium hanjuni sp. nov. and Microbacterium shimangi sp. nov. are proposed. The type strains are P01ᵀ (GDMCC 1.4682 T =JCM 37688 T ), P04ᵀ (=GDMCC 1.4683 T =JCM 37689 T ) and P06ᵀ (=GDMCC 1.4684 T =JCM 37690 T ), respectively.