Antibacterial Potentials of Lactic Acid Bacteria (LAB) Isolated from Cow Milk against Some Selected Food Spoilage Bacteria

Abstract

Lactic acid bacteria (LAB) are Gram positive, acid tolerant, generally non-spore forming, catalase negative, indole negative and rod or cocci in structure. LAB produce lactic acid as a major product of fermentative metabolism. This study was designed to determine the antibacterial activity of Lactic acid bacteria (LAB) against some selected food putrefaction bacteria. LAB were obtained from cow milk sold in Eke, Oye and Ogbete markets in Enugu, Enugu State and were transported to the Laboratory for isolation, characterization and identification using standard microbiological methods. The selected food spoilage bacteria were isolated from spoilt rice and cabbage and were identified in line with Clinical and Laboratory Standards Institute (CLSI) techniques. The organisms isolated include Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The antibacterial potential was done using agar well diffusion method in line with the CLSI protocol. The antibacterial assay carried out showed variant zones of inhibition ranging from 1 mm to 30 mm. LAB isolates from cow milk had highest zones of inhibition of 25 mm against E.coli, 30 mm against Staphylococcus aureusand 27 mm against Pseudomonas aeruginosa. From our study results, LAB isolated from cow milk possess antibacterial activity which could be harnessed for new drug development. Thus, the use of lactic acid bacteria in food preservation will be of immense benefits and also as a starter cultures in the production of so many fermented dairy products. They are as well known to possess Generally Regarded as Safe (GRAS) status with World Health Organization (WHO) and Joint Food and Agriculture Organization (FAO) approval. Lactic acid bacteria may therefore be considered as an alternative to the commonly used preservatives in response to consumers' demand for natural and less-processed products.