Kitasatospora humi sp. nov., isolated from a tropical peat swamp forest soil, and proposal for the reclassification of Kitasatospora psammotica as a later heterotypic synonym of Kitasatospora aureofaciens

A polyphasic approach was used to describe strain RB6PN24(T), a novel actinobacterium isolated from peat swamp forest soil collected from Rayong province, Thailand. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain belonged to the genus Kitasatospora and showed the highest sequence similarities to Kitasatospora kifunensis IFO 15206(T) (98.7%) and Kitasatospora acidiphila MMS16-CNU292(T) (98.5%). Strain RB6PN24(T) contained major amounts of meso-diaminopimelic acid, galactose, mannose and ribose in the whole-cell hydrolysates. MK-9(H 6) and MK-9(H 8) were the predominant menaquinones of the micro-organism. The polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides, an unidentified lipid, four unidentified aminolipids and six unidentified phospholipids. Mycolic acids were not present. The major fatty acids were iso-C 15 :0, iso-C 16:0, anteiso-C 15: 0, iso-C 17:0, anteiso-C 17:0 and C 16 :0. The draft genome size of strain RB6PN24(T) was 8.09 Mbp, with 72.1 mol% G+C content and predicted to contain at least 44 biosynthetic gene clusters encoding diverse secondary metabolites. Furthermore, the strain exhibited low average nucleotide identity and digital DNA-DNA hybridization values with K. acidiphila MMS16-CNU292(T) (89.1%, 42.4 %) and K. kifunensis DSM 41654(T) (79.5%, 25.5%). The results of phenotypic, chemotaxonomic, genotypic and phylogenetic analyses revealed that strain RB6PN24(T) represents a novel species of the genus Kitasatospora, for which the name Kitasatospora humi sp. nov. is proposed. The type strain is RB6PN24(T) (=TBRC 14818(T)=NBRC 115116(T)). In addition, the comparison of the whole genome sequences and phenotypic features suggested that Kitasatospora aureofaciens and Kitasatospora psammotica belong to the same species. Therefore, it is proposed that K. psammotica is reclassified as a later heterotypic synonym of K. aureofaciens.

Automated summary

A polyphasic approach was used to describe a novel actinobacterium strain RB6PN24(T) isolated from peat swamp forest soil in Thailand, which belongs to a new species Kitasatospora humi of the genus Kitasatospora. Phenotypic, genotypic, chemotaxonomic, and phylogenetic analyses revealed distinct differences between RB6PN24(T) and other Kitasatospora species.