Reclassification of streptomyces diastaticus subsp. Ardesiacus, streptomyces gougerotii and streptomyces rutgersensis

Abstract

We investigated the taxonomic relationships among Streptomyces diastaticus subsp. ardesiacus, Streptomyces diastaticus subsp. diastaticus, Streptomyces gougerotii and Streptomyces rutgersensis. The 16S rRNA gene sequence similarity between S. diastaticus subsp. ardesiacus and S. diastaticus subsp. diastaticus was 97.7%, whereas S. diastaticus subsp. diastaticus, S. gougerotii and S. rutgersensis showed 100% nucleotide sequence identity. In addition, S. diastaticus subsp. diastaticus, S. gougerotii and S. rutgersensis formed a single clade in the phylogenetic tree. Digital DNA–DNA relatedness between S. diastaticus subsp. diastaticus and S. diastaticus subsp. ardesiacus was only 22.8%, indicative of different species. In comparison, DNA–DNA relatedness values for S. diastaticus subsp. diastaticus, S. gougerotii and S. rutgersensis ranged from 95.8 to 97.2%, suggesting the three taxa belong to the same genomospecies. Previously reported phenotypic data also supported synonymy. Therefore, we propose that S. diastaticus subsp. ardesiacus should be classified as an independent species, Streptomyces ardesiacus sp. nov. The type strain is NBRC 13412T (=ATCC 3315T=CBS 713.72T=DSM 40496T=ISP 5496T=JCM 4745T=NBRC 3714T=NRRL B-1241T=RIA 1373T). Our data also suggests that S. rutgersensis and S. gougerotii should be reclassified as later heterotypic synonyms of S. diastaticus.