Diversity of members of the Streptomyces violaceusniger 16S rRNA gene clade in the legumes rhizosphere in Turkey

Large numbers of putatively novel streptomycetes were isolated from rhizosphere soils of Albizia distachya, Colutea arborescens, Gleditsia triancanthos, Medicago arborea, Robinia pseudoacacia, Sophora japonica, Spartium junceum, Tipuana tipu and Wisteria sinensis. Representative isolates were determined to 6 multi-membered and 11 single-membered colour groups based on their ability to form pigments on oatmeal and peptone yeast extract iron agars. The largest colour groups, which encompassed 40 isolates with morphological properties typical of members of the Streptomyces violaceusniger 16S rRNA gene clade, were tested for a characteristic PCR amplification product with taxon-specific primers. In spite of highest 16S rRNA gene nucleotide similarity among the isolated strains belonging to the S. violaceusniger 16S rRNA gene clade, it is evident from the phenotypic, molecular and chemical results obtained that many new species will emerge.