Microbispora oryzae sp. nov., isolated from leaves of rice plant (Oryza sativa L.).

Abstract

An endophytic actinomycete, designated strain RL4-1ST, was isolated from surface-sterilized leaves of rice plant (Oryza sativa L.) collected from Buri Rum province, Thailand. Its taxonomic status was determined using a polyphasic approach. Phylogenetic analysis based on the 16S rRNA gene sequences showed that the strain RL4-1ST belongs to the genus Microbispora and is most closely related to Microbispora rosea subsp. rosea ATCC 12950T (98.5%). The strain forms pairs of spores on short sporophores borne on the aerial mycelium. Polar lipid profile of strain RL4-1ST is diphosphatidylglycerol, hydroxy-phosphatidylethanolamine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides, ninhydrin-positive glycophospholipid, two unidentified phospholipids, an unidentified aminolipid, and an unidentified glycolipid. MK-9(H4), MK-9(H2), and MK-9 are major menaquinones of this organism. The predominant cellular fatty acids are iso-C16:0, C17:0 and C16:0. Strain RL4-1ST contains meso-diaminopimelic acid, glucose, madurose and ribose in whole-cell hydrolysates. The draft genome of strain RL4-1ST consists of 7.46 Mbp and has a G + C content 71.2 mol%. Digital DNA-DNA hybridization and average nucleotide identity values between the genome sequence of strain RL4-1ST with Microbispora rosea subsp. rosea ATCC 12950T are 26.0% and 80.7%, respectively. Based on data of genotypic, phenotypic, phylogenetic and chemotaxonomic analysis, strain RL4-1ST represents a novel species of the genus Microbispora, for which the name Microbispora oryzae sp. nov. is proposed. The type strain is RL4-1ST (=TBRC 14817T = NBRC 115115T).