The presence and phylogenetic position of polyketide synthase types I and II and nonribosomal peptide synthetase gene groups in Streptomyces strains Iz8, F9 and F6

The screening of polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) gene groups is a quick way to show the potential for antibacterial agent production and novel drugs discovery. With regard to this matter, the presence and the phylogenetic relationship of these gene clusters were studied in three Streptomyces strains.

 Materials & Methods:

PCR amplification of PKS types I, PKS type II, and NRPS genes was performed using three degenerate primer sets in Streptomyces strains Iz8, F9 and F6, respectively. To separate the same-sized DNA fragments with different sequences, PCR products cloned to pTG19-T vector and then transformed to Escherichia coli TOP10. Polyacrylamide gel was used for the sequences variation. The purified plasmids were sequenced and phylogenetic trees were constructed using Bayesian inference, implemented in the MrBayes.

PKS I clone 3 and 8, PKS II clone 4 and NRPS clone 5 were deposited in the NCBI GenBank database. Phylogenetic tree from aligned nucletotide or amino acide sequences of PKS I and II contained several differential clades. PKS I clone 8 and PKS II clone 4 were one of these clades. This could raise the production possibility of new antimicrobial agents.

Construction of phylogenetic tree and determination of evolutionary relationships confirmed possibility of the presence of gene clusters with new compositions and therefore new products in strains Iz8 and F9.