BEHAVIOR OF LISTERIA-MONOCYTOGENES IN MEAT AND ITS CONTROL BY A BACTERIOCIN-PRODUCING STRAIN OF LACTOBACILLUS SAKE

Lactobacillus sake Lb 706 can release a bacteriocin inhibitory to Listeria monocytogenes. In MRS broth, viable counts decreased rapidly when Lact. sake Lb 706 was added, whereas growth of the listerias was not affected by a bacteriocin-negative variant of the same Lactobacillus strain. Inhibition of L. monocytogenes was also observed in pasteurized minced meat inoculated with Lact. sake Lb 706. The bacteriocin produced is apparently effective in meat. However, the effect of the bacteriocin producer was less evident in minced meat than in broth. In comminuted cured raw pork filled into casings (German-type 'fresh Mettwurst'), L. monocytogenes was able to grow at a pH of 6.3, but addition of Lact. sake Lb 706 prevented the growth of listerias during the first few days after manufacture. At normal pH (5.7) L. monocytogenes did not multiply and addition of Lact. sake Lb 706 reduced viable counts of listerias by about one log cycle. Lactobacillus sake Lb 706 therefore may have some potential as a protective culture in meat products.