Research Article
Adeyemo SM, Agun TF and Ogunlu
Abstract
Lactic acid bacteria (LAB) have been found to produce antimicrobial agents that contribute to inhibition of pathogens and spoilage microorganism in food. This research aims at assessing and determining the antimicrobial substances produced by LAB isolated from ‘pupuru’ against food borne pathogens. Samples of ‘pupuru’ were collected from Ondo State, Nigeria and different species of LAB were isolated from them. LAB were identified using standard morphological and biochemical tests. They were tested against pathogenic organisms using the Agar well diffusion method. Antibacterial substances produced were also monitored for five days. A total of 18 LAB were isolated and identified as L. casei, L. delbrueckii, L. brevis, L. plantarum, L.pentosus, L. fermentum and L. acidophilus. Production of antimicrobial substances; Lactic acid, Diacetyl and Hydrogen peroxide ranges from (0.010–0.0196 g/L). The highest yield was obtained from L. plantarum and L. acidophilus; the least being L. pentosus. Reduction in pH was observed in the fermenting cassava from 5.8–3.5 on day five. LAB species from ‘pupuru’ had a considerable inhibitory effect on food borne pathogens Four species were tested for antagonistic activity and L. plantarum showed the highest zone of inhibition on Staphylococcus aureus (24 mm) and Pseudomonas aeruginosa (20 mm) respectively while the antimicrobial activity decreases with time. The antimicrobial activities of LAB were shown to significantly (p<0.05) compare with standard antibiotics used as control. LAB demonstrated high antimicrobial properties against food borne pathogens. This potential can be employed as starters in food industry to inhibit food spoilage microbes and contaminants.