Phylogenetic Characterization and Detection of Polyketide Synthase Type I and Non-ribosomal Peptide Synthases Genes in Micromonospora Strains Isolated from Chilean Marine Sediments

Abstract

There has been an increasing emphasis on the need to exploit un- and underexplored environments especially the marine environments for microbial and chemical diversity. Previous in-depth exploration of Chilean marine sediments have led to the isolation of members of the Micromonosporaceae, which require de-replication and characterization to establish taxonomic status along with screening of the isolates for the ability to produce bioactive compounds. This study was, therefore, embarked on with the aim of assessing phylogenetic relationship of the isolates and screening for novel polyketide synthases type I (PKS-I), non-ribosomal peptide synthases (NRPS) biosynthetic genes (BGC).  This involved culture, de-replication by the traditional colour grouping to select representative strains, amplification of 16S rRNA, PKS-I and NRPS genes, sequencing and phylogenetic analysis. Thirty-four representative strains were selected from 66 Micromonospora species. Following the 16S rRNA gene sequence analysis, 11 belonged to the genus Micromonospora, 7 strains residing in the genera Exiguobacterium and Bacillus. The phylogenetic analysis of the 16S rRNA gene sequences of the strains inferred that these strains are novel members of this sub-order.  The partial sequences of PKS-I and NRPS genes amplified from eight Micromonospora strains, produced matches with a variety of BGCs including Streptomyces noursei, S. neyagawaensis concanamycin A and Streptomyces sp. heptaene macrolide complex synthesis gene cluster. There exists an untapped microbial diversity in the Chilean marine sediments with great potential of been exploited for novel bioactive compounds as the search for newer and more potent natural products deepens.