A novel Gram-stain positive, aerobic, non-motile, non-spore-forming and rod-shaped strain designated 1204T was isolated from surface-sterilised stem tissue of maize planted in Fangshan District of Beijing, People's Republic of China. A polyphasic taxonomic study was performed on the new isolate. On the basis of 16S rRNA gene sequence similarity studies, this isolate belongs to the genus Microbacterium. High levels of 16S rRNA gene sequence similarity were found between strain 1204T and Microbacterium enclense NIO-1002T (98.8%) and Microbacterium proteolyticum RZ36T (98.4%) respectively. However, the DNA-DNA hybridization values between strain 1204T and its closely related species M. proteolyticum DSM 27100T and M. enclense DSM 25125T were 53.9 ± 1.6 and 20.9 ± 1.5% respectively. The DNA G+C content of strain 1204T was determined to be 68.0 mol%. The major fatty acids were found to consist of anteiso-C15:0 (37.6%), iso-C16:0 (28.6%) and anteiso-C17:0 (16.6%). The predominant menaquinone was MK-11 and the polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, an unidentified glycolipid and an unidentified lipid. The results of physiological and biochemical tests and minor differences in the fatty acid profiles allowed a clear phenotypic differentiation of strain 1204T from the closely related species in the genus Microbacterium. Thus, it was concluded that strain 1204T represents a novel species within the genus Microbacterium, for which the name Microbacterium zeae sp. nov. is proposed, with the type strain 1204T (= CGMCC 1.15289 = DSM 100750).
Keywords: Endophytes; Maize; Microbacterium.