The taxonomic position of two novel Actinoallomurus strains isolated from rhizosphere soil of wild rice (Oryza rufipogon Griff.) was established using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strains WRP6H-15T and WRP9H-5T were closely related to Actinoallomurus spadix JCM 3146T and Actinoallomurus purpureus TTN02-30T. Chemotaxonomic and morphological characteristics of both strains were consistent with members of the genus Actinoallomurus, while phenotypic properties, genome-based comparisons and phylogenomic analyses distinguished strains WRP6H-15T and WRP9H-5T from their closest phylogenetic relatives. The two strains showed nearly identical 16S rRNA gene sequences (99.9 %). Strain WRP6H-15T showed 68.7 % digital DNA-DNA hybridization, 95.9 % average nucleotide identity (ANI) based on blast and 96.4 % ANI based on MUMmer to strain WRP9H-5T. A phylogenomic tree based on draft genome sequences of the strains and representative of the genus Actinoallomurus confirmed the phylogenetic relationships. The genomes sizes of strains WRP6H-15T and WRP9H-5T were 9.42 Mb and 9.68 Mb, with DNA G+C contents of 71.5 and 71.3 mol%, respectively. In silico analysis predicted that the strains contain biosynthetic gene clusters encoding for specialized metabolites. Characterization based on chemotaxonomic, phylogenetic, phenotypic and genomic evidence demonstrated that strains WRP6H-15T and WRP9H-5T represent two novel species of the genus Actinoallomurus, for which the names Actinoallomurus soli sp. nov. (type strain WRP6H-15T=TBRC 15726T=NBRC 115556T) and Actinoallomurus rhizosphaericola sp. nov. (type strain WRP9H-5T=TBRC 15727T=NBRC 115557T) are proposed.
Keywords: Actinoallomurus; actinomycete; polyphasic taxonomy; wild rice.