Micromonospora cathayae sp. nov., isolated from the rhizosphere soil of Cathaya argyrophylla

A novel actinobacterium, strain HUAS 3(T), was isolated from the rhizosphere soil of Cathaya argyrophylla collected in Hunan Province, PR China. Strain HUAS 3(T) contained meso-diaminopimelic acid in the cell-wall peptidoglycan. The dominant menaquinones were MK-9(H-4), MK-9(H-6), MK-10(H-2) and MK-9(H-4). The polar lipids consisted of diphosphatidylglycerol, phospholipids, phosphatidylethanolamine, phosphatidylglycerol, phosphotidylinositol and phosphatidylinositol mannosides. The main cellular fatty acids (>5.0 %) were C-17 : 1 omega 8c, iso-C-16 : 0, C-18 : 1 omega 9c, iso-C-15 : 0, C(16 : 0 )and summed feature 3 (C-16 : 1 omega 6c and/or C-16 : 1 omega 7c). The DNA G+C content of the novel strain's genome sequence, consisting of 7 196 442 bp, was 72.8 mol%. The full-length 16S rRNA gene sequence analysis indicated that strain HUAS 3(T) belonged to the genus Micromonospora and showed highest similarities to Micromonospora fluminis A38(T) (99.44 %), Micromonospora echinospora DSM 43816(T) (99.23 %), Micromonospora tulbaghiae DSM 45142(T) (99.23 %), Micromonospora solifontis PPF5-17(T) (99.16 %) and Micromonospora endolithica DSM 44398(T) (98.96 %). Phylogenetic trees based on 16S rRNA gene sequences showed that strain HUAS 3(T) was closely related to M. fluminis A38(T), M. tulbaghiae DSM 45142(T) and M. solifontis PPF5-17(T). The phylogenomic tree revealed that strain HUAS 3(T) was closely related to Micromonospora pallida DSM 43817(T). However, the average nucleotide identity (ANIb/ANIm) and the digital DNA-DNA hybridization values between them were 84.75 /88.16 and 30.80 %, respectively, far less than the 95-96 and 70 % cut-off points recommended for delineating species. Furthermore, strain HUAS 3(T) was distinct from the type strain of M. pallida in terms of phenotypic and chemotaxonomic characteristics. In summary, strain HUAS 3(T) represents a novel Micromonospora species, for which the name Micromonospora cathayae sp. nov. is proposed. The type strain is HUAS 3(T) (=MCCC 1K08599(T)=JCM 36275(T)).