Antimicrobial Activity of Secondary Metabolites from a Soil Bacillus sp. 7B1 Isolated from South Al-Karak, Jordan

Soil is considered as a promising environment for discovering and isolating bacterial strains that are able to produce novel natural products. Therefore, a Gram positive Bacillus sp. 7B1 was isolated from a soil sample collected from south Al- Karak, Jordan. The bacterial isolate was cultivated, identified and its culture medium was extracted. The crude extract was purified using silica gel column chromatography. The antibacterial activity of the crude extract and the purified fractions was evaluated by agar diffusion test as well as by measuring the minimum inhibitory concentration in microbroth dilution assay. The produced crude extract was active only against the tested Gram positive bacteria, namely Bacillus subtilis, Micrococcus luteus and Staphylococcus aureus. Bioactivity-guided fractionations of the resulted crude extract led to the purification of compound (C_2). In the present work, Micrococcus luteus was the most susceptible bacterial test strain to compound (C_2) with a minimum inhibitory concentration of 25 μg/ml. Our findings highlighted the importance of soil bacterial isolates for production of compounds with interesting bioactivities that may contribute to the drug research field.