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 erythr

The genus <i>Saccharopolyspora</i> consists of Gram-positive bacteria that are found in nature. The <i>Saccharopolyspora</i> genus, belonging to the family <i>Pseudonocardiaceae</i> and order <i>Pseudonocardiales</i>, has shown considerable phylogenetic and taxonomic overlaps. Therefore, a phylogenetic, phylogenomic and comparative genomic investigation was conducted to elucidate the taxonomic position of four <i>Saccharopolyspora</i> taxa. Analysis of the 16S rRNA genes showed that the sequence similarity between the tested species ranged from 95.59 to 100%, with <i>Saccharopolyspora hirsuta</i> VKM Ac-666^T as the type species. Moreover, the analysis of digital DNA-DNA hybridization revealed that <i>Saccharopolyspora subtropica</i> CGMCC 4.7206ᵀ and <i>Saccharopolyspora thermophila</i> JCM 10664ᵀ were 97.97% and <i>Saccharopolyspora erythraea</i> DSM 40517ᵀ and <i>Saccharopolyspora spinosporotrichia</i> 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 <i>S. subtropica</i> Wu <i>et al.</i> 2016 and <i>S. thermophila</i> Liu <i>et al.</i> 2001 and <i>S. spinosporotrichia</i> Zhou <i>et al.</i> 1998 and <i>S. erythraea</i> corrig. (Waksman 1923) Labeda 1987, which support their reclassification.