Antimicrobial Activity of Bacteriocins against Bacterial Contaminants in Abattoir Wastewater

Abstract

Background: Abattoir wastewater is treated by physical, chemical and biological methods before release or reuse. These methods have high costs and the use of chemicals has adverse effects on the environment and human health. Aims: The research investigated the effect of bacteriocin treatment on bacteria in abattoir wastewater. Place and Duration of Study: Department of Microbiology, Michael Okpara University of Agriculture, Umudike. Methodology: Bacteria were isolated using standard microbiological methods and their identity confirmed using 16S rRNA method. Purified bacteriocins produced from lactic acid bacteria were assayed for antibacterial activity using the agar well diffusion method and used for treatment of abattoir wastewater samples. Abattoir wastewater samples were sterilized and inoculated with three isolated bacteria respectively. Plate counts were determined before treatment with bacteriocin extracts after which plate counts were read to determine if there were reductions in bacterial counts. Results: Bacteria isolated from abattoir wastewater include Escherichia coli, Enterobacter aerogenes, Staphylococcus aureus, Klebsiella oxytoca, Salmonella sp, and Bacillus cereus. Lactobacillus plantarum bacteriocin and Lactobacillus fermentum bacteriocin were assayed against Escherichia coli, Enterobacter aerogenes and Staphylococcus aureus. The bacteriocins displayed highest antagonistic effect on Staphylococcus aureus counts when used to treat abattoir wastewater. There was a decrease of 3.48 log cycles in Staphylococcus aureus counts after two hours of treatment with Lactobacillus fermentum bacteriocin in abattoir wastewater while there was a decrease of 2.97 log cycles in Staphylococcus aureus counts after two hours of treatment with Lactobacillus plantarum bacteriocin in abattoir wastewater. They exhibited least antagonistic effect on Enterobacter aerogenes with a decrease of 2.54 log cycles and 2.30 log cycles after two hours of treatment with Lactobacillus plantarum bacteriocin and Lactobacillus fermentum bacteriocin respectively. Treatment with consortium of the bacteriocins revealed higher activity with a decrease of 3.70 log cycles in Staphylococcus aureus counts after two hours of treatment. There was a decrease of 3.35 log cycles in Escherichia coli counts in the wastewater when treated with consortium of the bacteriocins. Conclusion: The results of this study indicate that bacteriocins have significant inhibitory activity against bacterial strains in abattoir wastewater and can be used as alternatives to the use of chemicals in the treatment of abattoir wastewater.