Fitness of Listeria monocytogenes and Other Listeria Species Isolated from Two Nova Scotia Watersheds

Abstract

Listeria monocytogenes is a foodborne pathogen known to colonize surfaces, form antimicrobial-resistant biofilms, and resist environmental stresses such as desiccation, helping it persist in food processing environments. Over 670 presumptive Listeria isolates collected from an urban and a rural Nova Scotia watershed were identified through sequencing of the 16S rRNA and/or sigB genes. L. monocytogenes, L. innocua, and L. seeligeri were isolated from both watersheds. L. welshimeri and L. fleischmannii were only isolated from the rural watershed. The fitness of each species was evaluated through motility, biofilm, desiccation and benzalkonium chloride (BAC) assays. L. fleischmannii and L. innocua formed significantly less biofilm. L. monocytogenes strains from the urban and rural watersheds were the most and least desiccation-resistant, respectively. Generally, L. fleischmannii was the most susceptible to BAC. This research provides greater insight into natural reservoirs of pathogenic Listeria and the factors that help Listeria persist in food processing plants.