Identification of Bioactive Compounds of Streptomyces spp. Isolated from Qom Lake Sediments and Evaluation of its Antimicrobial Activity against Pseudomonas aeruginosa

Abstract

Background: Marine sediments are rich sources for isolating active secondary metabolites from microorganisms. Among the microorganisms, Actinomycetes are highly important due to the production of various chemical compounds in a wide range of biological activities, such as antibacterial activity. Streptomyces is the most important genera in the family of Actinomycetes. As a member of this group, it has great potential in the production of secondary metabolites such as antibiotics, enzymes, herbicides, anti-carcinogenic, and other useful compounds. Objective: This study aims to identify bioactive compounds of Streptomyces isolated from sediments of the Salt Lake of Qom and to study their antimicrobial properties against standard strains of Pseudomonas aeruginosa. Methods: In this study, 20 samples were collected from a depth of 5 to 15-20 cm of sediment in the Salt Lake of Qom. Pure cultivations were then provided from these samples. This study used starch casein agar (SCA) to isolate streptomyces, and 35 Streptomyces were isolated. The disc diffusion method was used to explore the antimicrobial properties of Streptomyces against clinical strains of Pseudomonas aeruginosa and strains standard of Pseudomonas aeruginosa PTCC 1310. Results: Seven strains, including SCA3 SCB1, SCB4, SCB8, SCC15, SCC18, and SCC28 strains, had antimicrobial properties. In this study, the results show that SCC15 with the halo diameter of 17, 17, 15, and 19 contains the best antibacterial properties against clinical strains 1, 2 and 3 of Pseudomonas aeruginosa and Pseudomonas aeruginosa PTCC 1310. among the 16 peaks observed by GC/MS to identify bioactive compounds of Streptomyces, it was found that Bis (2-ethyl hexyl) phthalate, with 69.06 percent, had the highest peak production, which reflects the importance of phthalates in microbial activities. Conclusion: According to the results, the Salt Lake of Qom was one of the sources of Streptomyces. In addition, the isolated Streptomyces had antimicrobial properties against Pseudomonas aeruginosa isolates. It was also found that phthalate was the most bioactive substance of Streptomyces isolated.