Microbacterium populi sp. nov., isolated from Populus×euramericana bark

Five non-spore-forming, aerobic and Gram-stain-positive bacterial strains, 10-107-8(T), 1C-4, NHI3_6, 4107_1_2, and 3D-3, were isolated from Populus × euramericana bark collected in Puyang City, Henan Province, PR China. The isolates grew at 15-40 °C and pH 5-10. The optimum temperature and pH for growth were 30 °C and pH 8.0, respectively. Chemotaxonomic features included MK-10 and MK-11 as major menaquinones (type strain); predominating iso- and anteiso-branched cellular fatty acids; diphosphatidylglycerol and phosphatidylglycerol as major polar lipids (type strain); ornithine as the principal diamino acid of the cell-wall peptidoglycan (type strain); glycolyl type as cell-wall acyl type; and DNA G+C content of 66.8-67.6 mol%. These features were consistent with classification in the genus Microbacterium . Analysis of 16S rRNA gene sequence data indicated that the five isolates belonged to the genus Microbacterium and were closely related to Microbacterium halotolerans . A high 16S rRNA gene sequence similarity of 96.97% to M. halotolerans YIM 70130(T) was observed. The five isolates showed less than 96.20% 16S rRNA gene sequence similarity to the other species of the genus Microbacterium with validly published names. DNA-DNA relatedness of the five isolates with M. halotolerans JCM 13013(T) ranged from 35.62% to 44.36%. Considering the results of 16S rRNA gene sequence analysis and the physiological and biochemical characteristics, we propose that the five strains should be assigned to a novel species of the genus Microbacterium . The name proposed for the five strains is Microbacterium populi sp. nov., and the type strain is 10-107-8(T) ( =CFCC 11275(T) =KCTC 29152(T)).