ABSTRACT
Objectives: The paper aimed to isolate Streptomyces strain having the ability to produce antibacterial metabolites and optimize some environmental parameters for excellent antibiotic production.
Methods: Different soil samples were collected from extreme environments of desert regions at Karbala Province, Iraq. Actinomycetes were isolated using different media. The primary screening for antibacterial production was accomplished, and the antibacterial activities were tested against pathogenic bacteria, including Escherichia coli, Staphylococcus aureus, Streptococcus agalactiae, and Pseudomonas aeruginosa. The most potent strain was chosen for optimizing some of environmental parameters to increase the bioactive metabolite production. Different parameters were studied such as culture media, temperature, pH, and agitation rate.
Results: About eight Streptomyces strains were isolated from soil samples. All isolates appeared variable levels of antibiotic productions against Gram-positive and negative pathogenic bacteria, and the best one was Streptomyces sp. LHR 9. The antibacterial metabolite production from Streptomyces sp. LHR 9 was affected by various cultural parameters. Glucose soybean meal broth as a fermentation medium at pH 7 yielded the highest antibiotic production under the optimal fermentation conditions, including the temperature at 35°C with 200 rpm (revolution/min) agitation rate and 7 days incubation period.
Conclusion: The Streptomyces sp. LHR 9 showed antibacterial activity against both Gram-positive and negative pathogenic bacteria. It may consider as a potential source of drug production. Further study needs to purification and characterization of antibiotic and analyzes the mechanism for the antimicrobial activity of this bioactive compound.
Keywords: Streptomyces, Antibacterial metabolite, Optimization, Environmental condition.
