Purpose: This study applied meat (chicken and pork) juice as a minimal processed food model to investigate its effect on Campylobacter and Salmonella biofilm formation for a better understanding of biofilm formation in the real meat processing environment.
Methods: Meat juice was collected during raw meat freeze-thaw process and then sterilized by filtration. Bacterial biofilm formation level was determined using a live cell staining method, which is based upon the metabolic activity of bacterial cells. Confocal laser scanning microscope (CLSM) coupled with fluorescence cell stain was used to characterize the biofilm 3-D structure.
Results: In polystyrene 96-well plates, over 25% of chicken juice supplemented in Mueller Hinton broth (v/v) could significantly enhance the survival of Campylobacter in its biofilm (P<0.05). For Salmonella, Luria Bertani broth supplemented with 10% chicken juice (v/v) could lead to a significant increase compared to the control group (P<0.05). Similarly, meat juice could also support biofilm formation of Campylobacter and Salmonella in a microfluidic “lab-on-a-chip” platform, which was under a well-controlled flow condition. During the initial attachment stage of biofilm formation, more bacterial cells were present on the substrate conditioned with meat juice residues, compared to clean substrate materials. In CLSM images, the biofilms demonstrated different distribution patterns between laboratory media and meat juice.
Significance: These results validated the variation in Campylobacter and Salmonella biofilm formation between different conditions. In application, thorough cleaning of meat residues during meat production and handling are considered to be critical in reducing the load of Campylobacter and Salmonella in the environment and agri-food products.