Antibacterial Compound Productivity by Streptomyces spp. Isolated from Clinical Samples in Iraq: Optimization of Their Production

Background: Streptomyces can manufacture a variety of biologically active secondary metabolites (antibacterial compounds). Objectives: The study involved optimizing the conditions for antibacterial productivity of two selected Streptomyces isolates recovered from the clinical samples of patients. Materials and Methods: Two isolates of Streptomyces , Streptomyces isolate 04 (SI-04) and Streptomyces isolate 10 (SI-10), were selected and found to be antibiotic producers. Four different parameters were used to achieve maximum antibacterial productivity for both isolates. The parameters include the use of four different broth media for antibacterial productivity, the use of five various pH values (pH: 5, 6, 7, 8, 9), the use of a variety of incubation temperatures (26, 28, 30, 32, and 34°C), and the use of various incubation times (1, 2, 3, 4, 5, 6, and 7 days) and its relation to antibacterial productivity. The antibacterial ability of each Streptomyces isolate for productivity related to all parameters was determined by measuring the inhibition zone diameters against test bacterial isolates. Analysis of variance test was used for data analysis using SPSS V-25. Results: Results revealed that the optimization of antibacterial productivity was applied using the following parameters: soya bean broth 1 medium, pH adjusted at 7.0, and the incubation time for 4 days at 30°C for Streptomyces isolates SI-04 and soya bean broth 1 medium, pH adjusted at 7.0, and incubation for 5 days at 30°C for Streptomyces isolate SI-10. Conclusion: The optimization of antibacterial production conditions was an important and a crucial step for improving and enhancing the antibacterial productivity of Streptomyces spp.