IMPACT OF INTERSPECIES INTERACTIONS WITH PSEUDOMONAS SPP. ON BIOFILM FORMATION OF SALMONELLA AND LISTERIA MONOCYTOGENES, AND THEIR RESPONSE TO FOOD-RELATED STRESSES

Abstract

In this thesis, the presence of P. aeruginosa in dual-species culture could protected Salmonella cells in biofilms from sanitizer treatment by providing more extracellular polymeric substances, in laboratory conditions and chicken juice to simulate the poultry processing environment. The effect of P. fluorescens on the fate of L. monocytogenes biofilm cells was dependent on the inoculation sequence, with higher resistance (disinfection and desiccation) and lower transfer efficiency to salmon products observed in dual species biofilms previously colonized by P. fluorescens. At last, the presence of cultivable indigenous microorganisms along with temperature, culture medium and biofilm age, were found to have an impact on the survival of L. monocytogenes biofilms in simulated salmon processing environment. In conclusion, survival of Salmonella and L. monocytogenes biofilm cells could be enhanced by the presence of Pseudomonas spp., highlighting the importance of mixed species biofilms for pathogen control in food processing plants.