Microbacterium hydrothermale sp. nov., an actinobacterium isolated from hydrothermal sediment

Abstract

A Gram-stain-positive, aerobic, non-motile, rod-shaped bacterium, strain 0704C9-2T, was isolated from hydrothermal sediment of the Indian Ocean. The organism grew with 0–5 % (w/v) NaCl and at 10–37 °C, with optimal growth occurring with 1 % NaCl and at 28–30 °C. Comparative 16S rRNA gene sequence analysis revealed that strain 0704C9-2T belonged to the genus Microbacterium . It exhibited highest 16S rRNA gene sequence similarity with Microbacterium testaceum DSM 20166T (98.4 %). Levels of similarity with the type strains of all other recognized species of the genus Microbacterium were less than 98.0 %. DNA–DNA hybridization experiments with strain 0704C9-2T and its closest relative, M. testaceum DSM 20166T, revealed a low reassociation value of 42.9 %. The DNA G+C content of strain 0704C9-2T was 73.3 mol%. The cell-wall peptidoglycan contained ornithine and the acyl type was glycolyl. The major whole-cell sugars were mannose, galactose, rhamnose and glucose. The major cellular fatty acids were anteiso-C15 : 0, anteiso-C17 : 0, iso-C16 : 0 and iso-C15 : 0. The predominant menaquinones were MK-11, MK-10 and MK-12. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, two unknown glycolipids and an unknown phospholipid. On the basis of phenotypic, phylogenetic and genotypic data, strain 0704C9-2T represents a novel species within the genus Microbacterium , for which the name Microbacterium hydrothermale sp. nov. is proposed. The type strain is 0704C9-2T ( = LMG 27542T = CGMCC 1.12512T).