ANTIBACTERIAL PROPERTIES AND CHEMICAL COMPOSITION OF CELL FREE EXTRACTS OF BACILLUS SPECIES ISOLATED FROM A WASTE DUMP SITE IN ILOKUN ADO-EKITI.
Abstract
ABSTRACT Waste dumpsites serve as reservoirs for diverse microbial populations, including pathogenic and beneficial bacteria. The presence of antibiotic-producing bacteria in such environments presents an opportunity for exploring novel antimicrobial compounds. This study investigates the antibacterial properties and chemical composition of cell-free extracts of Bacillus spp isolated from a waste dumpsite in Ilokun, Ado-Ekiti, Nigeria. Microbiological analysis was conducted to determine total bacterial count. Bacillus spp were isolated from soil sample collected from waste dump site for antibacterial efficacy against bacterial isolates. Samples were collected from the dumpsite, and standard microbiological techniques, including sterilization, Gram staining, and biochemical characterization, were employed for bacterial identification. The total bacterial count in the waste dump samples ranged from 5.4×104 to 9.7×104CFU/ml, exceeding the standard atmospheric concentration for bioaerosols (3.0 log 10 CFU/ml). The pH of soil sample obtained from the dump site ranged from acidity 2.9 to 8.7 alkaline. The mineral/metal composition of the soil sample, high Iron (8.93 ± 0.04ppm) was observed, followed by nickel (6.07 ± 0.04ppm) while the least composition was observed in mercury (1.40 ± 0.00ppm). Morphological and biochemical analyses confirmed the presence of bacteria in significant proportions, accounting for Staphylococcus aureus (3.3%), Streptococcus spp (10%), Klebsiella pneumoniae (16.6%), Bacillus spp (16.6%), Clostridium spp (3.3%), Pseudomonas spp (20%) and E. coli (30%). Further analysis confirmed the presence of Bacillus spp, known for their ability to produce antimicrobial compounds. Cell-free extracts of Bacillus spp. grown in de Man, Rogosa, and Sharpe (MRS) medium exhibited growth Inhibition (mm) against S. aureus: 3.51, E. coli: 5.83, Streptococcus spp: 4.75. The inhibition was more pronounced against E. coli compared to Staphylococcus aureus and Streptococcus spp, suggesting a species-dependent susceptibility. Comparative analysis with previous studies revealed that these extracts exhibited growth inhibition similar to those of Lactobacillus spp. and lactic acid bacteria, known for their production of antimicrobial proteins and organic acids. These findings underscore the significance of waste dumpsites as potential sources of beneficial microorganisms with antibacterial properties. The presence of enteric bacteria and the high microbial load at the dumpsite further emphasize the public health implications of improper waste disposal. Given the growing concern over antibiotic resistance, the exploration of Bacillus spp. for antimicrobial agents presents an alternative strategy for developing bio-based therapeutics. Future research should focus on the chemical characterization of the bioactive compounds present in the cell-free extracts and their potential applications in clinical and industrial settings.
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