A whole-genome study suggests a taxonomic rearrangement of Saccharopolyspora subtropica as a later heterotypic synonym of Saccharopolyspora thermophila and Saccharopolyspora spinosporotrichia as a later heterotypic synonym of Saccharopolyspora erythraea.

Abstract

The genus Saccharopolyspora consists of Gram-positive bacteria that are found in nature. The Saccharopolyspora genus, belonging to the family Pseudonocardiaceae and order Pseudonocardiales, has shown considerable phylogenetic and taxonomic overlaps. Therefore, a phylogenetic, phylogenomic and comparative genomic investigation was conducted to elucidate the taxonomic position of four Saccharopolyspora taxa. Analysis of the 16S rRNA genes showed that the sequence similarity between the tested species ranged from 95.59 to 100%, with Saccharopolyspora hirsuta VKM Ac-666^T as the type species. Moreover, the analysis of digital DNA-DNA hybridization revealed that Saccharopolyspora subtropica CGMCC 4.7206ᵀ and Saccharopolyspora thermophila JCM 10664ᵀ were 97.97% and Saccharopolyspora erythraea DSM 40517ᵀ and Saccharopolyspora spinosporotrichia JCM 10303ᵀ reached 99.9%. In addition, the average nucleotide identity values for all the combinations exceed 99%, indicating little genomic variation for these strains. Our genomic data strongly indicate the close genetic affinity between S. subtropica Wu et al. 2016 and S. thermophila Liu et al. 2001 and S. spinosporotrichia Zhou et al. 1998 and S. erythraea corrig. (Waksman 1923) Labeda 1987, which support their reclassification.