Diversity of nonribosomal peptide synthetase and polyketide synthase gene clusters among taxonomically close Streptomyces strains

To identify the species of butyrolactol-producingStreptomycesstrain TP-A0882, whole genome-sequencing of three type strains in a close taxonomic relationship was performed.In silicoDNA-DNA hybridization using the genome sequences suggested thatStreptomycessp. TP-A0882 is classified asStreptomyces diastaticussubsp.ardesiacus. Strain TP-A0882,S. diastaticussubsp.ardesiacusNBRC 15402T,Streptomyces coelicoflavusNBRC 15399T, andStreptomyces rubrogriseusNBRC 15455Tharbor at least 14, 14, 10, and 12 biosynthetic gene clusters (BGCs), respectively, coding for nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs). All 14 gene clusters were shared byS. diastaticussubsp.ardesiacusstrains TP-A0882 and NBRC 15402T, while only four gene clusters were shared by the three distinct species. Although BGCs for bacteriocin, ectoine, indole, melanine, siderophores such as deferrioxamine, terpenes such as albaflavenone, hopene, carotenoid and geosmin are shared by the three species, many BGCs for secondary metabolites such as butyrolactone, lantipeptides, oligosaccharide, some terpenes are species-specific. These results indicate the possibility that strains belonging to the same species possess the same set of secondary metabolite-biosynthetic pathways, whereas strains belonging to distinct species have species-specific pathways, in addition to some common pathways, even if the strains are taxonomically close.