Sphaerisporangium rufum sp. nov., an endophytic actinomycete from roots of Oryza sativa L

Abstract

An endophytic actinomycete, strain R10-82T, isolated from surface-sterilized roots of rice (Oryza sativa L.) was studied using a polyphasic approach. Strain R10-82T produced branching substrate mycelia and developed spherical spore vesicles on aerial hyphae containing non-motile spores. The major cellular fatty acids were iso-C16 : 0, iso-C14 : 0 and 10-methyl C17 : 0. The predominant menaquinones were MK-9, MK-9(H2), MK-9(H4) and MK-9(H6). Rhamnose, ribose, madurose, mannose and glucose were detected in whole-cell hydrolysates. The diagnostic phospholipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol mannosides, hydroxylphosphatidylethanolamine and ninhydrin-positive phosphoglycolipids. These morphological and chemotaxonomic data were similar to those of the genus Sphaerisporangium . Analysis of the 16S rRNA gene sequence revealed that strain R10-82T was related most closely to Sphaerisporangium cinnabarinum JCM 3291T (98.3 % similarity). The DNA G+C content of strain R10-82T was 74 mol%. DNA–DNA relatedness data in combination with differences in the biochemical and physiological properties suggested that strain R10-82T should be classified as representing a novel species of the genus Sphaerisporangium , for which the name Sphaerisporangium rufum is proposed. The type strain is R10-82T ( = BCC 51287T = NBRC 109079T). An emended description of the genus Sphaerisporangium is also provided.