Carbon Catabolite Control is Important for Listeria monocytogenes Biofilm Formation in Response to Nutrient Availability

The foodborne pathogen Listeria monocytogenes has the ability to develop biofilm in food-processing environment, which becomes a major concern for the food safety. The biofilm formation is strongly influenced by the availability of nutrients and environmental conditions, and particularly enhanced in poor minimal essential medium (MEM) containing glucose rather than in rich brain heart infusion (BHI) broth. To gain better insight into the conserved protein expression profile in these biofilms, the proteomes from biofilm- and planktonic-grown cells from MEM with 50 mM glucose or BHI were compared using two-dimensional polyacrylamide gel electrophoresis followed by MALDI-TOF/TOF analysis. 47 proteins were successfully identified to be either up (19 proteins) or down (28 proteins) regulated in the biofilm states. Most (30 proteins) of them were assigned to the metabolism functional category in cluster of orthologous groups of proteins. Among them, up-regulated proteins were mainly associated with the pentose phosphate pathway and glycolysis, whereas a key enzyme CitC involved in tricarboxylic acid cycle was down-regulated in biofilms compared to the planktonic states. These data implicate the importance of carbon catabolite control for L. monocytogenes biofilm formation in response to nutrient availability.