Gordonia oryzae sp. nov., isolated from rice plant stems (Oryza sativa L.).

A novel endophytic actinomycete, designated strain RS15-1S, was isolated from surface-sterilized stems of Oryza sativa L. collected from Sisaket province, Thailand. The colony of strain was strong orange, catalase-positive and oxidase-negative. Growth occurred at a temperature range of 17-37 °C, at pH 4.0-9.0 and in the presence of 0-13 % (w/v) NaCl. Phylogenetic analyses based on the 16S rRNA sequences showed that strain RS15-1S belonged to the genus Gordonia and was closely related to Gordonia polyisoprenivorans DSM 44302 (98.8 %) and Gordonia rhizosphera DSM 44383 (98.4 %). The major cellular fatty acids were C16 : 0, C18 : 0 10-methyl (tbsa), C16 : 1ω7c/C16 : 1ω6c and C18 : 1ω9c. The menaquinones were MK-9(H2) and MK-8(H2). Strain RS15-1S contained meso-diaminopimelic acid, arabinose, galactose, mannose and ribose in whole-cell hydrolysates. The polar lipids of the strain were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol mannosides, an unidentified polar lipid and two unidentified phospholipids. The DNA G+C content was 66.3 mol%. In silico DNA-DNA hybridization of strain RS15-1S showed 48.3 and 20.5 % relatedness to its closest neighbours, Gordonia polyisoprenivorans DSM 44302 and Gordonia rhizosphera DSM 44383, respectively. Based on data of genotypic, phenotypic, phylogenetic and chemotaxonomic analysis, strain RS15-1S represents a novel species of the genus Gordonia, for which the name Gordonia oryzae sp. nov. is proposed. The type strain is RS15-1S (=TBRC 8485=NBRC 113446).