Spirosoma oryzae sp. nov., isolated from rice soil and emended description of the genus Spirosoma

A bacterial strain, designated RHs22(T), was isolated from a soil sample cultivated with rice in the Suwon region of South Korea. The cells were aerobic, Gram-stain-negative, non-spore-forming, non-flagellated rods or occasionally filaments. The strain grew at 10-37 °C (optimum, 28-30 °C), at pH 5.0-10.0 (optimum, 7.0) and in the presence of 0-1 % (w/v) NaCl (optimum, 0 %). Phylogenetically, the strain was closely related to members of the genus Spirosoma, as its 16S rRNA gene sequence had similarity of 90.3-92.1 % with respect to those of members of the genus Spirosoma, showing the highest sequence similarity with Spirosoma panaciterrae DSM 21099(T). Strain RHs22(T) revealed relatively low sequence similarities of less than 90 % with all the other species with validly published names. It contained MK-7 as the predominant menaquinone and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), C16 : 1ω5c, iso-C15 : 0 and iso-C17 : 0 3-OH as the main fatty acids. The polar lipids of strain RHs22(T) were phosphatidylethanolamine, one unknown aminolipid, two unknown aminophospholipids, one unknown phospholipid and five unknown lipids. The DNA G+C content was 57.0 mol%. Phylogenetic, phenotypic and chemotaxonomic data obtained in this study indicate that strain RHs22(T) represents a novel species of the genus Spirosoma, for which the name Spirosoma oryzae sp. nov. is proposed. The type strain is RHs22(T) ( = KACC 17324(T) = DSM 28354(T)). An emended description of the genus Spirosoma is also proposed.