Functional Characterization of Polyketide Synthase Clusters in Streptomyces anandii J6.

Streptomyces species are well-known for their antifungal properties and the production of diverse secondary metabolites, including non-ribosomal peptides and polyketides. These metabolites can be identified through various genetic techniques, allowing for the investigation of gene functions using whole-genome databases. Numerous studies have explored the genetic functions of Streptomyces using advanced techniques, such as CRISPR-Cas9 mutagenesis, to generate site-specific mutant strains. In this study, we re-identified Streptomyces sp. J6 as Streptomyces anandii J6 through whole-genome sequencing and average nucleotide identity (ANI) analysis. The type II and type III polyketide synthase clusters (PKS: clusters 9, 10, and 12) were further studied using CRISPR-Cas9 for functional analysis, revealing the role of srsA in the biosynthesis of alkylresorcinols, which are phenolic lipids with antifungal properties. These results indicate that metabolites belonging to the polyketide family produced by Streptomyces plays a significant role in the biocontrol activity of microorganisms against plant diseases. Furthermore, the findings suggest that specific PKS profiling enables the rapid and efficient screening of a large number of microbial candidates, thereby facilitating the selection of promising biocontrol agents.