Main Article Content
Abstract
This study investigated the isolation and characterization of antibiotic-producing microorganisms from selected agricultural soils in Oko Community, Anambra State. Ten agricultural soil samples were collected and processed using standard microbiological techniques. The isolates were characterized on cultural and biochemical properties, and their antimicrobial activities were evaluated at 12.5, 25, 50, 75 and 100 mg/mL by the agar well diffusion method. Thirty bacterial isolates were recovered and presumptively identified as Bacillus sp. (36.7%), Pseudomonas spp. (26.7%), Streptomyces sp. (23.3%) and Staphylococcus sp. (13.3%). Antimicrobial screening showed concentration-dependent inhibition. Streptomyces sp. exhibited the highest activity, with an inhibition zone of 28.9 ± 0.5 mm at 100 mg/mL, followed by Bacillus sp. (26.8 ± 0.4 mm), Staphylococcus sp. (25.6 ± 0.3 mm) and Pseudomonas spp. (22.7 ± 0.4 mm). No inhibition was observed with the DMSO negative control. Agricultural soils in Oko Community therefore harbour cultivable microorganisms with promising antimicrobial activity, particularly Streptomyces and Bacillus. Further molecular identification and chemical characterization of the active metabolites are recommended.