CENTRAL OF LISTERIA-MONOCYTOGENES IN-GROUND BEEF BY LACTOCIN-705, A BACTERIOCIN PRODUCED BY LACTOBACILLUS-CASEI CRL-705

The effectiveness of Lactobacillus casei CRL 705 as well as that of La ctocin 705, the associated bacteriocin produced, in reducing populatio n levels and growth of Listeria monocytogenes in sterile and non-steri le ground beef was studied. Predetermined numbers of L. monocytogenes and concentrations of Lactocin 705 were added to the meat slurries. Li steria in the bacteriocin-treated and control samples during incubatio n at 20 degrees C were enumerated as CFU on Bacto blood agar base. Res ults indicated that reduction in numbers of Listeria was largest with high levels of Lactocin 705 and few initial cell numbers of the pathog en present in the meat slurry. However, when the producer strain was a dded to the slurry, no significant inhibition was detected, Furthermor e, inhibition by listeria was shown to be greater when meat slurries w ere heat-treated.