Abstract

Antibiotic-resistance is growing around the world and is now a serious health concern. It is thus essential to find novel, extremely potent antibiotics. The Streptomyces genus has attracted the attention of researchers worldwide because it is the most well-known producer of antibiotics. This study aimed to isolate Streptomyces strains from the Jordan Valley soil and evaluate their ability to produce bioactive substances. Twenty bacterial strains were isolated, and the antimicrobial activity was performed against five types of pathogenic bacteria (Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa) using the modified cross-streak method for primary screening and the agar diffusion assay for secondary screening. One isolate, the SR2 strain, showed the highest bioactivity in the primary and secondary screenings against two pathogenic bacteria (B. subtilis and P. aeruginosa). It caused zones of inhibition of about 17–28 mm at 500 µg disc-1. Therefore, this bacterial strain was selected for further studies. 16S rDNA sequencing was used to identify the SR2 strain. The identification findings revealed a 98% similarity to Streptomyces labedae. Overall, this study demonstrated that Streptomyces labedae SR2 isolated from Jordan Valley soil has the potential to produce effective antimicrobial compounds against both Gram-positive and Gram-negative pathogenic bacteria.