Dual-species biofilms formation between dominant microbiota isolated from a meat processing industry with Listeria monocytogenes and Salmonella enterica: Unraveling their ecological interactions.

Alternatives to combat the persistence of pathogens need to consider the microbiota established on industrial surfaces as they can influence the protection or replacement (i.e. reduction/inhibition) of pathogens. The objective of the present study was to determine the ecological interactions established in dual-species biofilms between Listeria monocytogenes and Salmonella enterica as target pathogens, and isolates recovered from a meat processing facility (i.e.Pseudomonas fluorescens, Pseudomonas fragi, Bacillus safensis, Bacillus megaterium, and Candida zeylanoides). Results showed different ecological relations in biofilms depending on the species evaluated. Pseudomonas spp. did not influence the growth of either pathogen, although tested species tended to protect the pathogens in the structures generated. B. megaterium and C. zeylanoides affected the two pathogens differently, demonstrating a reduction of L. monocytogenes adhered cells within the formed biofilm. B. safensis reduced or presented non-influence on S. enterica depending on the incubation conditions. Contrarily, B. safensis was the microorganism that demonstrated the highest replacement capacity for L. monocytogenes, reducing its growth by up to 4 log CFU/cm. The in vitro study of bispecies biofilms is important for the food industry, helping to understand how they behave and to find an effective way to eliminate them.