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

An endophytic actinomycete, designated strain RL4-1S(T), 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 RL4-1S(T) belongs to the genus Microbispora and is most closely related to Microbispora rosea subsp. rosea ATCC 12950(T) (98.5%). The strain forms pairs of spores on short sporophores borne on the aerial mycelium. Polar lipid profile of strain RL4-1S(T) is diphosphatidylglycerol, hydroxy-phosphatidylethanolamine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides, ninhydrin-positive glycophospholipid, two unidentified phospholipids, an unidentified aminolipid, and an unidentified glycolipid. MK-9(H-4), MK-9(H-2), and MK-9 are major menaquinones of this organism. The predominant cellular fatty acids are iso-C-16:0, C-17:0 and C-16:0. Strain RL4-1S(T) contains meso-diaminopimelic acid, glucose, madurose and ribose in whole-cell hydrolysates. The draft genome of strain RL4-1S(T) 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 RL4-1S(T) with Microbispora rosea subsp. rosea ATCC 12950(T) are 26.0% and 80.7%, respectively. Based on data of genotypic, phenotypic, phylogenetic and chemotaxonomic analysis, strain RL4-1S(T) represents a novel species of the genus Microbispora, for which the name Microbispora oryzae sp. nov. is proposed. The type strain is RL4-1S(T) (= TBRC 14817(T) = NBRC 115115(T)).

Automated summary

A novel endophytic actinomycete strain RL4-1S(T) belonging to the genus Microbispora was isolated from rice plants in Thailand, showing distinct morphological characteristics, polar lipid profiles, major menaquinones, and cellular fatty acids compared to related species. Genotypic, phenotypic, phylogenetic, and chemotaxonomic analyses support the proposal of Microbispora oryzae sp. nov. for this strain with unique features.