Microbacterium mangrovi sp. nov., an amylolytic actinobacterium isolated from mangrove forest soil
Strain MUSC 115T was isolated from mangrove soil of the Tanjung Lumpur river in the state of Pahang, Peninsular Malaysia. Cells of this strain stained Gram-positive and were non-spore-forming, short rods that formed yellowish-white colonies on different agar media. The taxonomy of strain MUSC 115T was studied by a polyphasic approach, and the organism showed a range of phylogenetic and chemotaxonomic properties consistent with those of the genus Microbacterium . The cell-wall peptidoglycan was of type B2β, containing the amino acids ornithine, alanine, glycine, glutamic acid and homoserine. The muramic acid was of the N-glycolyl form. The predominant menaquinones detected were MK-12, MK-13 and MK-11. The polar lipids consisted of phosphatidylglycerol, phosphoglycolipid, diphosphatidylglycerol, two unidentified lipids, three unidentified phospholipids and four unidentified glycolipids. The major fatty acids of the cell membrane were anteiso-C15 : 0 and anteiso-C17 : 0. The whole-cell sugars detected were ribose, glucose, mannose and galactose. Based on the 16S rRNA gene sequence, strain MUSC 115T showed the highest sequence similarity to Microbacterium immunditiarum SK 18T (98.1 %), M. ulmi XIL02T (97.8 %) and M. arborescens DSM 20754T (97.5 %) and lower sequence similarity to strains of other species of the genus Microbacterium . DNA–DNA hybridization experiments revealed a low level of DNA–DNA relatedness (less than 24 %) between strain MUSC 115T and the type strains of closely related species. Furthermore, BOX-PCR fingerprint comparison also indicated that strain MUSC 115T represented a unique DNA profile. The DNA G+C content determined was 70.9±0.7 mol%, which is lower than that of M. immunditiarum SK 18T. Based on the combination of genotypic and phenotypic data, it is proposed that strain MUSC 115T represents a novel species of the genus Microbacterium , for which the name Microbacterium mangrovi sp. nov. is proposed. The type strain is MUSC 115T ( = MCCC 1K00251T = DSM 28240T = NBRC 110089T).