MITIGATING BIOFILM FORMATION BY DAIRY-ASSOCIATED BACTERIA USING SUPERHYDROPHOBIC WAX COATINGS

Introduction. Microbial contamination of dairy products, caused by biofilm-forming bacteria, is of great concern to the dairy industry, making it one of the leading sectors impacted by food loss. It was previously emphasized that preventing biofilm formation on work surfaces of the dairy industry would be a more desirable option than treating it. However, currently there is no technology that can completely prevent biofilm formation without causing undesirable side effects.

Our results indicate the possibility of developing novel approach towards prevention of biofilm formation by exploiting superhydrophobic wax surfaces. We, therefore, evaluated the effect of the generated surfaces on the ability of Bacillus species, isolated from the dairy environment, to form surface-associated biofilm.

Methods. The coatings were prepared by thermal deposition of waxes on glass, polystyrene steel and polytetrafluoroethylene substrates. Biofilm formation on the wax-coated and control surfaces was examined in batch and continuous culture (using constant depth film fermenter, CDFF). Biofilms were analyzed with confocal laser scanning microscopy (CLSM). Quantification of live bacteria on the coated substrates was performed using the plating method.

Results. CLSM images show that the developed coatings demonstrate strong inhibition of biofilm formation on all tested substrates during short- and long-term incubation with bacteria, in batch and continuous culture. Quantification of live bacteria, attached to the wax-coated surfaces, indicates significant reduction in bacterial adhesion compared to uncoated control, providing effective inhibition of biofilm formation. Furthermore, the coatings retain their structure/functionality during incubation in milk and other food-related media.

Conclusions. The exceptional ability of the studied coatings to inhibit biofilm formation by dairy isolates indicates about potential feasibility of their application for resisting biofilms in the dairy industry.