Resistance of Multispecies Biofilms to Sanitization with Chlorine, Peroxyacetic Acid, and Ozone Nano-bubble−Activated Water

Microbial communities that permanently persist in food processing facilities challenge food safety and food quality. Sanitization resistance is enhanced by the formation of biofilms, but sanitization resistance in multispecies biofilms remains poorly documented. It was therefore the objective of this study to determine the resistance of biofilms formed by 12 microbial communities to 200 ppm chlorine, 40 ppm peracetic acid, and nano-bubbles with 7 ppm ozone. The composition of the microbial communities was analyzed by culture and by 16S rRNA gene amplicon sequencing. The microbial communities, previously isolated from a pork processing facility, consisted of 6-19 bacterial strains each and together comprised 130 strains representing 19 genera. All 12 communities formed dense biofilms at 4 °C and, to a lesser extent (P < 0.05), during growth at 25 °C. The resistance of the microbial communities to chlorine, peracetic acid, and ozone nano-bubbles was specific for the microbial community and the incubation temperature (P < 0.05). One or more of the microbial communities resisted chlorine, peracetic acid, or ozone nano-bubbles, but none of the microbial communities was resistant to all three sanitizers. Sanitization altered the composition of microbial communities in a strain-specific manner. Results imply that incorporating a rotation of several different sanitizers as part of routine sanitization protocols may be a practical and effective strategy to improve sanitization outcomes and reduce the persistence of biofilms in meat processing facilities.