Application of lysostaphin-producing lactobacilli to control staphylococcal food poisoning in meat products

The potential of lysostaphin-producing strains of Lactobacillus curvatus (Lys(+)) to prevent food-borne illness by Staphylococcus aureus was investigated under practical conditions. A response surface model was developed to estimate the effect of pH, temperature, and salt concentration on the lysostaphin activity. The model was applied to fermenting sausages, and a 90% reduction of lysostaphin activity at ripening was predicted. The residual activity was sufficiently high to reduce staphylococcal counts by 10(4) to 10(5) CFU/g within 2 to 3 days to below the level of detection. These results were obtained in pilot scale experiments with L. curvatus (Lys(+)) as a starter culture and S. aureus as well as Staphylococcus carnosus as model contaminants. The applicability of L. curvatus (Lys(+)) as a protective culture was studied in a mayonnaise-based meat salad. Upon incubation at 25 degrees C the staphylococci were rapidly killed within 24 h, whereas in the presence of the isogenic Lys(-) strain the staphylococci grew up to numbers of 10(7) CFU/g.