Epilithic Biofilms of Lake Baikal: Screening of and Diversity of NRPS/PKS Genes in Genomes of Heterotrophic Microorganisms. NRPS/PKS Genes in Microorganism

Many secondary metabolites in bacteria are synthesized by enzyme complexes of polyketide synthase (PKS) and non-ribosomal peptide synthase (NRPS). A positive PCR signal was marked in 30 from 125 heterotrophic strains using screening for presence of polyketide synthase genes. The occurrence of PKS genes was as follows: 40% in the phylum Firmicutes (Bacillus, Paenibacillus), 20% in Proteobacteria, and 12% in Actinobacteria. PKS genes were identified in six strains of the genera Bacillus and Paenibacillus. We obtained 43 sequences in cloning and sequencing of the amplification products. Homology of amino acid sequences with those represented in GenBank was 96-100%. We detected genes involved in biosynthesis of antibiotics (bacillaen, difficidin, erythromycin, sorangicin, batumin, and plipastatin) and antitumor agents (epothilone, kalikulina and bryostatin) among the homologues. The strains of Bacillus, Paenibacillus are potential producers of antimicrobial compounds and may be of practical interest to biotechnological purposes.