Microbacterium wangyouchuni sp. nov. and Microbacterium zouquanmingi sp. nov., isolated from soil in Mongolian marmot (Marmota sibirica) burrows

Four Gram-stain-positive, aerobic, non-motile and rod-shaped bacterial strains, designated A82 T , A588, A196 T and A204, were isolated from soil samples collected from Marmota sibirica burrows in Hulun Buir, Nei Mongol Autonomous Region, China. All four strains grew at 4–30 °C, pH 6.0–10.0 and 0–6.5% (wt/v) NaCl, and they were positive for oxidase and catalase activities. Phylogenetic analysis of 16S rRNA gene sequences indicated that the four strains belonged to two species within the genus Microbacterium . Strains A82 T and A588 exhibited the highest sequence similarity to Microbacterium profundi Shh49 T (98.83%) and Microbacterium murale 1 Gi-001 T (98.67%). Strains A196 T and A204 were most closely related to Microbacterium aerolatum NBRC 103071 T (99.10%) and Microbacterium shaanxiense CCNWSP60 T (98.63%). Comparing the four isolates with their reference strains showed that average nucleotide identity and digital DNA–DNA hybridization values were below the accepted species-delineation benchmarks of 95–96 and 70%, respectively. For the type strains A82 T and A196 T , the DNA G+C content was 64.7 and 65.4 mol%, respectively. Chemotaxonomic analysis revealed that both type strains possessed MK-13 as the sole respiratory quinone. Additionally, diphosphatidylglycerol, phosphatidylglycerol and unidentified glycolipids were the major polar lipids. Furthermore, anteiso -C 15 : 0 was identified as the major fatty acid, and the diamino acid in the cell-wall peptidoglycan contained alanine, glutamic acid, glycine, aspartic acid and ornithine. Therefore, strains A82 T /A588 and A196 T /A204 represent two novel species within the genus Microbacterium . Microbacterium wangyouchuni sp. nov. (A82 T /A588, type strain A82 T =GDMCC 1.5865 T =JCM 38342 T ) and Microbacterium zouquanmingi sp. nov. (A196 T /A204, type strain A196 T =GDMCC 1.6024 T =JCM 38357 T ) are proposed.