Potential of selected bacteriocinogenic lactic acid bacteria to control Listeria monocytogenes in nitrite-reduced fermented sausages

The antilisterial activity of four strains of bacteriocinogenic lactic acid bacteria has been tested in vitro and in a meat model, as an alternative to reduce nitrite added to fermented sausages. Cell-free supernatants were obtained after bacterial growth under monoculture and coculture conditions, both at 32 degrees C/16 h and 22 degrees C/72 h. After being adjusted to different pH, supernatants were assayed for inhibition of Listeria monocytogenes inoculated on tryptone soya broth added with 0.8% bacteriological agar. The highest inhibition was observed for Pediococcus acidilactici MP14 and the commercial starter P. acidilactici B-LC-20, especially when they were grown in coculture with Staphylococcus spp. meat starters. Lactococcus lactis MP11 showed lower antilisterial activity, and it was dependant on pH. In a fermented sausage model prepared without and with 50% of the maximum level of sodium nitrite allowed by the European Union (i.e. 75 mg/kg) both pediococci confirmed the activity observed in vitro, and reduced Listeria numbers by 1.3-1.4 log cfu/g in the absence of nitrite and 0.8 log cfu/g in its presence. Therefore P. acidilactici MP14, which had been isolated from an artisanal fermented sausage, has shown potential interest for biopreservation applications that must be confirmed in studies under real sausage manufacture conditions.