Evaluation of antibacterial activity of new Streptomyces species isolated from soils of eastern Gilan province and optimization of antibacterial compounds produced by it

Abstract

Streptomyces are capable of producing secondary metabolites including antibiotics and the main environment of these microorganisms is soil. The purpose of this study was to isolate and evaluate Streptomyces producing antibacterial compounds from different parts of east of Gilan province and optimizing antibacterial compounds produced by them. In this study, after isolation and purification of Streptomyces, to investigate its antibacterial activity against tested pathogenic microorganisms including Micrococcus luteus PTCC 1408, Bacillus cereus PTCC 1154, Staphylococcus aureus PTCC 1189, Pseudomonas aeruginosa PTCC 1310, Salmonella typhi PTCC 1609 and Proteus mirabilis PTCC 1776 were investigated. Streptomyces was identified based on morpholigaical, biochemical, physiological, 16SrRNA gene sequencing and phylogenetic analysis. Optimization of various factors in the content of production of antibacterial compounds were investigated. In this study, 16SrRNA gene sequencing revealed that the isolate belonged to Streptomyces genus and with the highest similarity (95.70%) to Streptomyces malachitospinus indicating significant differences at species level and it can be introduced as a new species. This isolate showed significant activity against pathogenic microorganisms and in relation to optimizing the maximum production of optimal antibacterial compounds in culture medium, pH, temperature, carbon and nitrogen sources and incubation time were ISP2, 7, 28 0C, glycerol, yeast extract and 7 days, respectively.The results show that the soils of the eastern regions of Gilan province are a rich source of antimicrobial compounds, which due to the resistance of the pathogenic microorganisms to antimicrobial drugs, is essential for the production of antimicrobial compounds of natural origin.