Abstract

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A dramatic increase in bacterial resistance towards currently available antibiotics has raised worldwide concerns for public health. Therefore, bacteriocins which are antimicrobial peptides (AMPs) have emerged as a promisingly new group of therapeutic agents for managing infectious diseases and possibly in food preservation. The present study focusses on the isolation of novel bacteriocins from an indigenous sample of cow milk and testing of its antimicrobial activity. Two bacteria isolates (Pediococcus acidilactici and Lactobacillus plantarum) isolated from raw cow milk gotten from Yenegoa, Bayelsa state, Nigeria produced potent bacteriocins on De-Mann Rogosa and Sharpe agar and these were shown to have inhibitory activity against the pathogenic bacteria Escherichia coli. The bacteriocins were heat stable, remaining active at temperatures up to 100°C and functioned well over a wide pH range of 0-10. There was a reduction in activity of the bacteriocins after treatment with proteinase K and peptidase, thus confirming the proteinaceous nature of the compounds. These bacteriocins displayed bacteriostatic and bactericidal activity against E. coli, with a minimum inhibitory concentration of 12.5 μg/ml and minimum bactericidal concentration of 25μg/ml which is lower than that of the conventional antibiotics chloramphenicol (50μg/ml) used as positive control. The bacteriocins produced by lactic acid bacteria isolated from cow milk in this work is effective in inhibiting the growth of E. coli and thus may be of use as a food preservative in the storage of food or as therapeutic agent for the treatment of infections caused by multi-drug resistant E. coli.

Keywords: Bacteriocin, Antimicrobial peptide, drug resistance