Fermented sausages as specific rich source for bacteriocinogenic strains

FONTANA CECILIA; BASSI DANIELA; SAAVEDRA LUCILA; VIGNOLO GRACIELA; COCCONCELLI PIER S.

Munich

Simposio; 1st International Symposium on Fermented Meats; 2011

technischen Universitat Munchen

Fermented sausages are known to be shelf-stable products, in which an inhibitory sequence of hurdles (NaCL, NO2/NO3, low EH and aw) are present. Food-poisoning Staphylococcus aureus, Salmonella and Clostridium perfringes have been traditionally implicated in fermented sausage contamination while Listeria monocytogenes and shiga toxin-producing Escherichia coli have recently emerged as major public health concern. However, hurdles during the manufacturing process may not be sufficient to prevent the survival of pathogens; an additional hurdle to reduce contamination risk would be the use of competitive bacteriocin-producing starter cultures referred to as bioprotective cultures. In this study, lactic acid bacteria (LAB) isolated from traditional Argentinean fermented sausages were analyzed for their ability to produce bacteriocins with activity against food-poisoning microorganisms. Strains of L. sakei (18), L. curvatus (5) L. plantarum (10), P. acidilactici (7) and E. faecium (10) were preliminary screening by an agar spot test and the well diffusion assays. All strains were also tested by PCR to search the presence of bacteriocin encoding genes. L. sakei, L. curvatus, and E. faecium showed a great potential for bacteriocin production, being mainly active against L. monocytogenes. The antimicrobial substances of these strains revealed high thermostability, most of the activity was maintained at temperatures up to 100 ºC, but the inhibitory effect decreased if the crude extract was autoclaved. The sensibility to the treatment with trypsin, proteinase K and papain was different and strain dependent. The presence of Sakacin P, Sakain Q, Curvacin A, genes were detected in bacteriocin producing lactobacilli. While not all enterococci results positive for enterocins A and enterocins B genes. Because bacteriocinogenic LAB are more competitive than non-producing variants, the application of such strains as functional starter culture may improve their competitiveness leading to a more controlled and standardized fermentation process.