Plantaricin 35d, a biopreservative for the control of Listeria monocytogenes in smoked salmon samples

The antibacterial activity of plantaricin 35d - a bacteriocin produced by t he lactobacillus strain Lactobacillus plantarum 35d, isolated from seasoned sausages - has been evaluated against eight strains of Listeria monocytoge nes. The active substance has been characterized and the results showed: th e optimal temperature for production, the kinetics of growth, the mode of a ction, the heat-resistance, the stability to time and to different pH value s. Subsequently the crude extract substance or the producer micro:organism was added, as biopreservative, in smoked salmon samples artificially contam inated with L, monocytogenes of different source and the bacterial counts d uring the shelf-life period were evaluated. The study confirmed the active growth of L. monocytogenes in salmon samples at refrigerated temperature wh ereas the treated samples presented a trend growth lower about 1-3 log duri ng the same period of time. In both tests the difference between the bacter ial count remained notable until and over the sixteenth week.