Abstract
A novel actinobacterial strain, designated HUAS TT1(T), was isolated from the rhizosphere soil of Camellia oleifera collected from Changde City, Hunan Province, China. Sequence analysis of the full-length 16S rRNA gene revealed that strain HUAS TT1(T) belonged to the genus Saccharothrix and shared the highest sequence similarities with Saccharothrix yanglingensis Hhs.015(T) (99.30%), Saccharothrix carnea NEAU-yn17(T) (98.89%), Saccharothrix hoggarensis SA181(T) (98.89%), Saccharothrix saharensis SA152(T) (98.82%), and Saccharothrix longispora NRRL B-16116(T) (98.75%). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain HUAS TT1(T) was related to Saccharothrix yanglingensis Hhs.015(T) and Saccharothrix longispora NRRL B-16116(T). Phylogenetic analysis based on whole-genome sequences and 120 core gene sequences showed that the evolutionary neighbors of strain HUAS TT1(T) were Saccharothrix hoggarensis SA181(T) and Saccharothrix saharensis SA152(T). However, the ANIb/m and dDDH values between the whole-genome sequences of strain HUAS TT1(T) and Saccharothrix hoggarensis SA181(T)/Saccharothrix saharensis SA152(T) were 85.82%/88.80 and 32.90%, 86.42%/89.43, and 34.40%, respectively, well below the 95-96 and 70% cut-off points recommended for delineating species, suggesting that strain HUAS TT1(T) is a novel Saccharothrix species. This result was further verified by the phenotypic and chemotaxonomic differences between them. Therefore, according to the above data, strain HUAS TT1(T) represents a novel species of the genus Saccharothrix, for which the name Saccharothrix camelliae sp. nov. is proposed. The type strain used was HUAS TT1(T) (=MCCC 1K09364(T) = JCM 37292(T)). In addition, the phenotypic, chemotaxonomic, and genotypic characteristics, as well as the phylogenetic information, indicated that S. yanglingensis CGMCC 4.5627(T) and S. longispora CGMCC 4.1357(T) belong to the same species. Therefore, on the basis of these results and Rule 42 of the Bacteriological Code, we propose that Saccharothrix yanglingensis is a later heterotypic synonym of Saccharothrix longispora, for which an emended description is given.