A multi-scale analysis of the effect of complex viscoelastic models on Listeria dynamics and adaptation in co-culture systems

Abstract

Natural antimicrobials are of interest to replace traditional food decontamination methods: they are milder and maintain desirable sensory characteristics. However, efficacy can be affected by food structure/composition, thus structural effects in a co-culture pathogen/microflora system are investigated. Listeria was grown planktonically (liquid broth) or on a biphasic viscoelastic system, in monoculture with/without artificial nisin, or in co-culture with Lactococcus lactis (nisin/non-nisin producing). Microbial growth kinetics were monitored and advanced microscopy techniques were utilized to quantify cellular interactions and spatial organization. Microstructural effects are observed on the kinetics, with differences in monoculture/co-culture. Significant microscopic differences are observed in spatial organization and colony size. We are the first to observe changing growth location for all species in monoculture/co-culture, with differences in colony size/organization through stationary phase. This study provides insight into the environmental stress response/adaptation of Listeria grown on structured systems in response to L. lactis and natural antimicrobials.