Assessing an environmental Listeria strain for its ability to survive and form biofilms in the presence of background microflora isolated from the dairy production environment

Obj 1. Understand the influence of background microflora isolated from Listeria positive and negative sites within a dairy plant on growth and biofilm-formation of Listeria. Abstract: The ability of Listeria monocytogenes to adhere and form biofilms on floor surfaces is a significant concern for the dairy sector since these properties determine their persistence in the dairy processing environment. The current multistate listeriosis outbreak linked to ice cream, which has hospitalized 23 people and killed one, serves as a reminder of the significance of reducing the presence of this pathogen in the processing environment. Listeria is well-known for its resilience to extreme environmental stresses such as sanitizers and disinfectants used to clean plant floors. Widespread usage of these chemicals in processing plants has aided the development of resistance in Listeria, ultimately posing a risk for product cross-contamination. Metagenomic study of the associated background microbial community with Listeria in a dairy plant can provide genomic insights, and aid in predicting community functional potential as a factor in Listeria presence, possibly by supporting or limiting (competitive exclusion, CE) its growth and biofilm formation. CE is a natural bacterial phenomenon in which one bacterial species competes with another for resources and/or space in a habitat, successfully reducing the number of cells or excluding the competing species. CE can be the result of the production of antimicrobials such as bacteriocins, and organic acids either acting directly against the species it is competing with or acting on the environment altering the pH or alternatively physically outcompeting the other bacterial species. As biofilms protect Listeria from chemical cleaners and disinfectants, the use of metabolic by- products from microorganisms having the potential to competitively exclude Listeria may assist sanitation approaches in controlling, preventing, or eradicating Listeria.