Spirosoma oryzicola sp. nov., isolated from dried rice husk

Strain RHs26(T) is an aerobic, Gram- stain- negative, non- flagellated and rod- or filamentous- shaped (1.0-1.1x2.3-50 mu m) bacterium that was isolated from dried rice husk. It was positive for oxidase and catalase, hydrolysed starch and Tween 80, and weakly hydrolysed CM- cellulose. The strain grew at temperatures between 10 and 37 degrees C (optimum, 28 degrees C), in 0-1 % NaCl (optimum, 0 %) and at pH 6.0-9.0 (optimum, pH 7.0-8.0). The predominant membrane fatty acids were summed feature 3 (C-16:1 omega 7c and/or C-16: 1 omega 6c), C-16: 1 omega 5c, iso-C-15: 0 and iso- C-17: 0 3- OH. The major polar lipids were phosphatidylethanolamine, an unidentified aminolipid, two unidentified aminophospholipids and two unidentified lipids. The predominant quinone was menaquinone MK- 7. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain RHs26(T) belongs to the genus Spirosoma, presenting the highest sequence similarity to Spirosoma agri S7-3-3(T) (95.8 %). The genomic DNA G+C content of strain RHs26(T) was 49.5 %. Strain RHs26(T) showed the highest orthologous average nucleotide identity (OrthoANI) and digital DNA-DNA hybridization (dDDH) values of 76.4 % and 20.0 % with S. agri KCTC 52727(T) while sharing OrthoANI and dDDH values of 74.6 % and 19.2 % with Spirosoma terrae KCTC 52035(T), the closest relative in the phylogenomic tree. Based on the results of a polyphasic taxonomic study, strain RHs26(T) represents a novel species in the genus Spirosoma, for which the name Spirosoma oryzicola sp. nov. is proposed. The type strain is RHs26(T) (=JCM 35224(T)=KACC 17318(T)).