Spirosoma humi sp. nov., Isolated from Soil in South Korea

A Gram-stain-negative, non-motile, rod-shaped, aerobic bacterial strain, designated S7-4-1T, was isolated from soil in Gyeongsangnam-do, South Korea and characterized using a polyphasic approach to determine its taxonomic position. Phylogenic analysis based on the 16S rRNA gene sequence showed that strain S7-4-1T belonged to the family Cytophagaceae and was most closely related to Spirosoma fluviale MSd3T (96.2%), ‘Spirosoma radiotolerans’ DG5A (96.0%), Spirosoma pulveris JSH5-14T (95.9%), and Spirosoma linguale DSM 74T (95.8%). The G+C content of the genomic DNA of the isolate was 49.0 mol%. The strain contained summed feature 3 (C16:1ω7c/C16:1ω6c; 41.0%), C16:1ω5c (24.9%), and C15:0 iso (9.3%) as the major fatty acids, menaquinone MK-7 as the predominant respiratory quinone, and phosphatidylethanolamine and an unidentified aminophospholipid as the main polar lipids, which supported its affiliation with the genus Spirosoma. The results of physiological and biochemical tests allowed the genotypic and phenotypic differentiation of the isolate from recognized Spirosoma species. On the basis of its phenotypic properties, genotypic distinctiveness, and chemotaxonomic features, strain S7-4-1T represents a novel species of the genus Spirosoma, for which the name Spirosoma humi sp. nov. is proposed. The type strain is S7-4-1T (= KCTC 52729T = JCM 32132T).