Catechol-type siderophore producer Streptomyces spp. with quorum-quenching activity isolated from wild medicinal plants rhizosphere

Abstract

Traditional medicinal plants represent a unique source for the isolation of Streptomycetes and antimicrobial compounds. Antimicrobial activity of Streptomyces isolates collected from the rhizosphere of different native medicinal plants in Iran, was investigated against Gram-positive and Gram-negative bacteria. Multi-omics analysis was performed to identify active compounds corresponding to the observed bioactivities. Since cell-to-cell communication mediated by N-acyl homoserine lactones (AHLs) is important for the virulence of Gram-negative pathogenic bacteria, quorum quenching activity of the isolates and their ability to degrade C6-HSL and C8-HSL were tested. Two highly related Streptomyces isolates derived from the Helichrysum rubicundum and Rumex acetosa rhizosphere, respectively, exhibited bioactivity against pathogenic indicator bacteria. Metabolite analysis of extracts obtained from liquid cultures of both isolates revealed the production of the catechol-peptide siderophores streptobactin and tribenarthin. Proteomic analysis confirmed the presence of proteins encoded by the streptobactin and lidamycin biosynthetic gene clusters. Quorum quenching activity of the strains and AHL-degrading enzyme production was confirmed using a GFP producing biosensor and LC-MS analysis. This study demonstrates catecholate siderophore production and QQ potential of two Streptomyces isolates from medicinal plants rhizosphere from Mishan Plain, Hamedan Province, Iran using metabolomics and proteomics analysis. Production of streptobactin by terrestrial Streptomyces sp. strains was confirmed for the first time.