Impact of Nutrient Restriction on the Structure of Listeria monocytogenes Biofilm Grown in a Microfluidic System
Biofilm formation by the pathogen Listeria monocytogenes is a major concern in       food industries. The aim of this work was to elucidate the effect of nutrient       limitation on both biofilm architecture and on the viability of the bacteria in       microfluidic growth conditions. Biofilm formation by two L. monocytogenes strains       was performed in a rich medium (BHI) and in a 10-fold diluted BHI (BHI/10) at 30        degrees C for 24 h by using both static conditions and the microfluidic system       Bioflux. In dynamic conditions, biofilms grown in rich and poor medium showed       significant differences as well in structure and in the resulting biovolume. In       BHI/10, biofilm was organized in a knitted network where cells formed long       chains, whereas in the rich medium, the observed structure was homogeneous       cellular multilayers. Biofilm biovolume production in BHI/10 was significantly       higher than in BHI in these dynamic conditions. Interestingly, biovolume of dead        cells in biofilms formed under limited nutrient conditions (BHI/10) was       significantly higher than in biofilms formed in the BHI medium. In the other       hand, in static conditions, biofilm is organized in a multilayer cells and       dispersed cells in a rich medium BHI and poor medium BHI/10 respectively. There       was significantly more biomass in the rich medium compared to BHI/10 but no       difference was noted in the dead/damaged subpopulation showing how L.       monocytogenes biofilm could be affected by the growth conditions. This work       demonstrated that nutrient concentration affects biofilm structure and the       proportion of dead cells in biofilms under microfluidic condition. Our study also       showed that limited nutrients play an important role in the structural stability        of L. monocytogenes biofilm by enhancing cell death and liberating extracellular        DNA.
Limited nutrients Extracellular DNA Listeria monocytogenes Biofilm structure Microfluidic system