A bacteriocin-like substance produced from Lactobacillus pentosus 39 is a natural antagonist for the control of Aeromonas hydrophila and Listeria monocytogenes in fresh salmon fillets

Here, we studied the ability of Lactobacillus pentosus 39, a BLS (Bacteriocin-like substance)-producing strain, to control the growth of Aeromonas hydrophila ATCC 14715 and Listeria monocytogenes ATCC 19117 artificially added to fresh salmon fillets at refrigeration temperatures and under simulated cold-chain break conditions. At refrigeration temperatures, Lb.pentosus 39 protective culture and its putative bacteriocin significantly reduced the A. hydrophila counts compared with the control (2.1 and 1.4 logCFU/g reductions, respectively). Similar behaviour was observed for L.monocytogenes (3.6 and 1.3 logCFU/g reductions, respectively). Under simulated cold-chain break conditions, an increase in temperature up to 30°C for 12h produced an evident increase in the development of A.hydrophila, L.monocytogenes, but also of Lb.pentosus 39, with a consequent increase in BLS production. Thus, this condition resulted in a greater reduction of both pathogens compared with samples stored at 4°C throughout the experiment (2.8 logCFU/g reduction for A.hydrophila and 5.8 logCFU/g reduction for L.monocytogenes). In samples treated with the putative bacteriocin alone, a less marked decrease was observed. Our study demonstrates the capability of Lb.pentosus 39 to control the growth of psychrotrophic bacteria in an experimental seafood model system. A similar biopreservation technology could provide more prolonged shelf life during storage of ready-to-eat seafood, ensuring safety, even under extreme conditions.