The Biodiversity and Antimicrobial Activity of Bacteria Isolated from the Bottom Sediments of the Chukchi Sea

Abstract

Two hundred and forty eight strains of heterotrophic microorganisms were isolated from bottom sediments of the Chukchi Sea. A 16S rRNA gene sequence analysis was used to classify representatives of 33 genera that belong to the phyla Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. Phylogenetic analysis showed that at least eight bacterial groups displayed 97−98% similarity of 16S rRNA gene sequence and may be new taxa. Screening of the antimicrobial activity revealed 40 strains that are capable of inhibiting the growth of two or more indicator microorganisms. Active strains were represented by bacteria of the genera Bacillus, Paenibacillus, Terribacillus, Virgibacillus (phylum Firmicutes), Streptomyces, Pseudonocardia, Nocardiopsis (Actinobacteria) and, to a lesser degree, by gram-negative bacteria Shewanella, Psychrobacter (class Gammaproteobacteria), Massilia (class Betaproteobacteria), and Arenibacter (phylum Bacteroidetes). Detection of gene fragments of polyketide synthase (PKS-1) and nonribosomal peptide synthetase (NRPS) by the PCR method using degenerate primers in 23 strains suggests that the studied bacteria can serve as a source of biologically active metabolites relating to polyketides and/or nonribosomal peptides.