ISOLATION FROM FOOD SOURCES, OF LACTIC-ACID BACTERIA THAT PRODUCED ANTIMICROBIALS

The potential of lactic acid bacteria, isolated from a variety of foods, to inhibit indicators representative of spoilage and pathogenic bacteria associated with food products was examined. Fruit and vegetables were a poor source of lactic acid bacteria but large numbers were readily isolated on MRS agar from cheese, milk and meat samples. Approximately 1000 isolates from each of the food samples were examined by the deferred antagonism procedure to determine their ability to inhibit Staphylococcus aureus, Listeria innocua and Pseudomonas fragi. Listeria innocua was the bacterium predominantly inhibited by isolates from the cheese, milk and meats, but antagonism was also observed to a lesser extent against the other indicators. The only inhibition observed for isolates from vegetable material was directed against Staph. aureus. The majority of inhibitor producers were effective against only one of the indicators but a small number were isolated which inhibited two or three.