Production of antimicrobial agents by Bacillus spp. isolated from Al-Khor coast soils, Qatar

Bacilli are Gram-positive, sporulating bacteria that can be found in diverse habitats, but mostly in soil. Many recent studies showed the importance of their antimicrobial agents that mainly target other Gram-positive bacteria. This study was conducted to assess the antibacterial activity of Al-Khor coastal soil Bacillus strains against four bacterial strains (Staphylococcus aureus, Staphylococcus epidermis, Escherichia coli, and Pseudomonas aeruginosa) by agar diffusion method as well as investigating best strain antibiotic production in liquid medium. The 25 isolated strains were identified using physical and biochemical tests. Results show that most strains possess significant antibacterial potential against S.  aureus and S. epidermis, but however less toward E. coli. Strain 2B-1B optimum activity was achieved using Luria Bertani broth and at 35°C, with pH 9. Therefore, antimicrobial compounds from these strains can be good candidates for future antibiotics production. Further screening for antimicrobial agents should be carried out in search of novel therapeutic compounds.   Key words: Al-Khor, zone of inhibition, Bacillus, coastal soil, antimicrobial agent.