Solicola gregarius gen. nov., sp. nov., a soil actinobacterium isolated after enhanced cultivation with Micrococcus luteus culture supernatant

An actinobacterial strain, designated A5X3R13(T), was isolated from a compost soil suspension supplemented with extracellular material from a Micrococcus luteus-culture supernatant. The strain was cultured on tenfold-diluted reasoner's 2A agar. The cells were ovoid-to-rod shaped, non-motile, Gram-stain-positive, oxidase-negative, catalase-positive and had a width of 0.5 mu m and a length of 0.8-1.2 mu m. The results of both 16S rRNA-based phylogenetic and whole-genome analyses indicate that A5X3R13(T) forms a distinct lineage within the family Nocardioidaceae (order Propionibacteriales). On the basis of the 16S rRNA gene sequence, A5X3R13(T) was closely related to Aeromicrobium terrae CC-CFT486T (96.2%), Nocardioides iriomotensis IR27-S3(T) (96.2%), Nocardioides guangzhouensis 130(T) (95.6%), Marmoricola caldifontis YIM 730233T (95.5 %), Aeromicrobium alkaliterrae KSL-107(T) (95.4%), Aeromicrobium choanae 9H-4T (95.4%), Aeromicrobium panaciterrae Gsoil 161(T) (95.3 %), and Nocardioides jensenii NBRC 14755(T) (95.2 %). The genome had a length of 4915 757 bp, and its DNA G+C content was 68.5 mol %. The main fatty acids were 10-methyl C-17:0, C-16:0, C-15:0, C-18:0, C-17:0 and iso-C-16:0. The main polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and two unidentified phospholipids. MK-9(H 4) was the predominant respiratory quinone. The peptidoglycan type was A3 gamma (A41.1) and contained alanine, glycine, glutamic acid and ll-diaminopimelic acid in a molar ratio of 1.2 :0.9:1.0:0.8. On the basis of the results of the phylogenetic and phenotypic analyses and comparisons with other members of the family Nocardioidaceae, strain A5X3R13(T) is proposed to represent a novel species within a novel genus, for which the name Solicola gregarius gen. nov., sp. nov. is proposed. The type strain is A5X3R13(T) (=DSM 112953(T)=NCCB 100840T).