Effectiveness and functional mechanism of a multicomponent sanitizer against biofilms formed by Escherichia coli O157:H7 and five Salmonella serotypes prevalent in the meat industry

Authors: Wang, Rong; ZHOU, YOU - University Of Nebraska; Kalchayanand, Norasak - Nor; Harhay, Dayna; Wheeler, Tommy

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2019
Publication Date: 4/1/2020
Citation: Wang, R., Zhou, Y., Kalchayanand, N., Harhay, D.M., Wheeler, T.L. 2020. Effectiveness and functional mechanism of a multicomponent sanitizer against biofilms formed by Escherichia coli O157:H7 and five Salmonella serotypes prevalent in the meat industry. Journal of Food Protection. 83(4):568-575. https://doi.org/10.4315/0362-028X.JFP-19-393.
DOI: https://doi.org/10.4315/0362-028X.JFP-19-393

Interpretive Summary: Biofilms are surface-attached microbial communities with a tremendous impact on public health and food safety. In the meat industry, biofilms remain a serious concern because many foodborne pathogens including E. coli O157:H7 and Salmonella enterica can form biofilms in many different areas that are very tolerant to sanitization. Thus, the meat industry is in need of not only the effective sanitizer products but also an easy-to-implement protocol that can be applied to the processing environment and the various equipment. We evaluated the effectiveness of the sanitizer product Decon-7 that can be deployed as foam or liquid solution to cover the different areas as needed in the plants. Our study found that this product was effective, even at 10% of its recommended concentration, in reducing E. coli O157:H7 and Salmonella biofilms on contact surfaces to the non-detectable level, and it also prevented pathogen recovery growth after the treatment. Results also indicated this product was able to dissolve the connection between bacterial cells and the contact surface, thus, destroyed the biofilm structure, killed bacterial cells and removed the colonized biofilm mass. Therefore, this product with an easy-to-implement protocol covering all areas in the processing environment provides an option that the meat industry may consider for their biofilm prevention and control program.

Technical Abstract: Biofilm formation by Escherichia coli O157:H7 and Salmonella enterica at meat processing plants poses a potential risk of meat product contamination. Many common sanitizers are unable to completely eradicate biofilms formed by these foodborne pathogens because of the three-dimensional biofilm structure and the presence of bacterial extracellular polymeric substances (EPSs). A novel multifaceted approach combining multiple chemical reagents with various functional mechanisms was used to enhance the effectiveness of biofilm control. We tested a multicomponent sanitizer consisting of a quaternary ammonium compound (QAC), hydrogen peroxide, and the accelerator diacetin for its effectiveness in inactivating and removing Escherichia coli O157:H7 and Salmonella enterica bio'lms under meat processing conditions. E. coli O157:H7 and Salmonella biofilms on common contact surfaces were treated with 10, 20, or 100% concentrations of the multicomponent sanitizer solution for 10 min, 1 h, or 6 h, and log reductions in biofilm mass were measured. Scanning electron microscopy (SEM) was used to directly observe the effect of sanitizer treatment on biofilm removal and bacterial morphology. After treatment with the multicomponent sanitizer, viable E. coli O157:H7 and Salmonella biofilm cells were below the limit of detection, and the prevalence of both pathogens was low. After treatment with a QAC-based control sanitizer, surviving bacterial cells were countable, and pathogen prevalence was higher. SEM analysis of water-treated control samples revealed the three-dimensional biofilm structure with a strong EPS matrix connecting bacteria and the contact surface. Treatment with 20% multicomponent sanitizer for 10 min significantly reduced biofilm mass and weakened the EPS connection. The majority of the bacterial cells had altered morphology and compromised membrane integrity. Treatment with 100% multicomponent sanitizer for 10 min dissolved the EPS matrix, and no intact biofilm structure was observed; instead, scattered clusters of bacterial aggregates were detected, indicating the loss of cell viability and biofilm removal. These results indicate that the multicomponent sanitizer is effective, even after short exposure with dilute concentrations, against E. coli O157:H7 and S. enterica biofilms.