Screening for type I polyketide synthases genes of endophytic Streptomycetes isolated from Parthenium hysterophorus L.

Abstract

Polyketides are a vital group of secondary metabolites comprising of antifungal, antibacterial as well as anticancer agents. The multifunctional enzymes responsible for the biosynthesis of these secondary metabolites are polyketide synthases (PKS) in which polyketide synthases type I (PKS-I) is mainly responsible for highly assorted group of metabolites with substantial medical importance. In this study molecular screening was done using six sets of degenerate primers to determine the presence of PKS-I gene cluster in endophytic Streptomyces isolated from the weed Parthenium hysterophorus L. A total of 40 endophytes were isolated and identified by morphological, biochemical and physiological characterization as belonging to the genus Streptomyces. The 16S rRNAgene sequencing of the selected isolates exhibited maximum similarity with different species of Streptomyces such as Streptomyces rochei (99%), Streptomyces litmocidini (99%), Streptomyces enissocaesili (99%), Streptomyces djakartensis (99%), Streptomyces olivaceus (99%), Streptomyces spp. (99%), Streptomyces plicatus (99%), Streptomyces geysiriensis (99%) and Streptomyces vinaceusdrappus (99%). The molecular screening revealed the presence of PKS-I gene with a PCR amplification products of size ∼300 bps, ∼320 bps and ∼700 bps in the isolates RT-13, RT-43, RT-47, RT-49, RT-54, RT-56, RT-57, RT-58, RT-59, RT-61 and RT-65 through all the six sets of primers used. To the best of our understanding no previous study has been carried out reporting the molecular screening of PKS-I genes in endophytic Streptomyces from Parthenium hysterophorus L. The results provide an insight into an unexplored environment containing endophytic Streptomyces harboring the polyketide synthases gene which if further investigated may lead to a new source of antimicrobial agents.