Streptomyces malaysiensis subsp. samsunensis comb. nov. and reclassification of Streptomyces solisilvae Zhou et al. 2017 as a heterotypic synonym of Streptomyces malaysiensis Al-Tai et al. 1999

Taxonomic relationships were investigated among Streptomyces malaysiensis Al-Tai et al. 1999, Streptomyces samsunensis Sazak et al. 2011 and Streptomyces solisilvae Zhou et al. 2017. Phylogenetic analyses suggested that these three species are closely related. Digital DNA-DNA hybridization value and average nucleotide identity based on blast+ between S. malaysiensis JCM 10672T and S. solisilvae HNM0141T were 99.8 and 99.9%, whereas those between S. samsunensis DSM 42010T and the remaining two were 75.4-75.6 and 95.0-96.5%, respectively. Their major phenotypic characteristics resembled each other except for the utilizations of myo-inositol and d-xylose by S. samsunensis. All the type-I polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) gene clusters were conserved between type strains of S. malaysiensis and S. solisilvae, but the type strain of S. samsunensis harboured 4 specific PKS and NRPS gene clusters instead of 11 clusters present in type strains of S. malaysiensis and S. solisilvae. Therefore, S. solisilvae and S. samsunensis were reclassified as a later heterotypic synonym of S. malaysiensis and S. malaysiensis subsp. samsunensis comb. nov., respectively. Based on the reclassifications, scientific names of whole genome sequence-published non-type strains related to the species were reviewed and updated.