Micrococcus endophyticus sp. nov., isolated from surface-sterilized Aquilaria sinensis roots

Abstract

A Gram-positive bacterial strain, designated YIM 56238T, was isolated from plant roots (Aquilaria sinensis), and characterized by using a polyphasic approach. Strain YIM 56238T grew optimally at pH 7.0-8.0 and at 28 °C. Analysis of the 16S rRNA gene sequence of strain YIM 56238T indicated that it belongs to the genus Micrococcus. Chemotaxonomic data strongly supported the classification of this strain within the genus Micrococcus: the cell-wall peptidoglycan contained lysine, glutamic acid, alanine and glycine; the predominant menaquinones were MK-8(H2) (63.6 %) and MK-7(H2) (21.1 %); the phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and an unknown ninhydrin-negative phospholipid; and the major cellular fatty acids were iso-C15:0 (30.95 %) and anteiso-C15:0 (53.75 %). The G+C content of the genomic DNA was 72.9 mol%. A number of physiological features were found that clearly distinguished strain YIM 56238T from recognized species of the genus Micrococcus. DNA-DNA hybridization studies suggested that the novel strain represents a separate genomic species. On the basis of the data, therefore, strain YIM 56238T represents a novel species of the genus Micrococcus, for which the name Micrococcus endophyticus sp. nov. is proposed. The type strain is YIM 56238T (=DSM 17945T=KCTC 19156T).