بررسي عصاره هاي حاصل از كشت سويه‌هاي استرپتوميست و خواص زيستي آن‌ها

Investigation of Non-Ribosomal Peptides from Streptomyces Strains an‎d Their Biological Properties

زيست شناسي سلولي مولكولي و ميكروبيولوژي

In light of increasing bacterial resistance to synthetic antibiotics, the production of natural antibiotics from microbial sources like Streptomyces has become a necessity. These bacteria are capable of producing antibiotic substances that can serve as effective alternatives to chemical antibiotics. Natural antibiotics not only have advantages in terms of human body compatibility an‎d fewer side effects compared to chemical drugs, but also have high potential for treating bacterial infections due to their natural origin. In this research, two previously isolated Streptomyces bacterial strains were used. The main objective of the study was to examine the antagonistic effects of these strains against pathogenic bacteria. The target bacteria included methicillin-resistant Staphylococcus aureus (MRSA), Enterococcus, an‎d Bacillus subtilis. In the continuation, to investigate growth kinetics an‎d determine the minimum inhibitory concentration, casein starch agar medium was used. The fermentation process was carried out for 10 days. During this period, bacterial growth an‎d antibiotic production were eva‎luated. This research phase helped us understan‎d how these bacteria operate under different environmental conditions an‎d how they can more effectively produce antibiotic substances. After fermentation, bacterial extracts were purified using spectrophotometric an‎d various chromatographic methods. These methods were used to isolate an‎d identify biologically active substances in the extracts. The results showed that these Streptomyces strains have an inhibitory effect against the mentioned gram-positive bacteria. However, no inhibitory effect was observed against gram-negative bacteria such as E. coli, Salmonella, Klebciella, an‎d Pseudomonas.The research results indicate that the used Streptomyces strains have high potential for antibiotic substance production. Strains IZ8 an‎d IZ6 showed the highest expression of antibacterial factors at the end an‎d middle of the first growth curveʹs decline phase, respectively. Additionally, this investigation revealed that the isolated Streptomyces strains have a different growth curve compared to other bacteria; cellular weight increases an‎d decreases irregularly in liquid medium as a sign of growth. In fact, these fluctuations are continuous growth/death stages.

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