An increasing antimicrobial resistance among phytopathogenic bacteria has shown significant problems in the soil ecosystem, since these pathogens can cause variety of plant diseases as well as economic damage to various plant crops. In 2019, losses from phytopathogen-caused illnesses in five major crops, wheat, rice, maize, potato, and soybean, were 10.2%, 10.8%, 8.5%, and 8.9%, respectively [1]. Current methods used to control these plant pathogens are chemicals, which could be harmful for the environment and threatening to human health [2]. Therefore, bacteriocins, a heterogeneous group of ribosomally synthesized antimicrobial peptides with the ability to kill closely related or a diverse range of bacteria species, could be used to overcome this problem [3]. Bacteriocins are much safer to use than some of the chemicals, moreover, due to their specificity towards purposive targets it comes off with no side effects.
The aim of this study was to identify bacteriocins that are secreted by microorganisms that have been isolated from the soil and may have an impact on phytopathogenic bacteria. 63 isolates were isolated from the soil and screened in order to evaluate their antibacterial activity against 9 phytopathogenic bacteria strains, such as Pectobacterium carotovorum, Xanthomonas vesicatoria, etc. We successfully identified two bacteria strains: Streptomyces sp. AB3 and Bacillus sp. DM1.10 that produce antibacterial substances. Genome analysis of AB3 and DM1.10 strains revealed gene clusters associated with bacteriocin biosynthesis. One of the AB3 gene clusters is presumably responsible for biosynthesis of a lasso peptide type bacteriocin. In this study, we describe heterologous expression of genes responsible for the lasso peptide bacteriocin biosynthesis in Escherichia coli cells.