Study on the Removal Effect of Salmonella typhimurium Biofilm

Objective: This research focused on the effects of different disinfectants, preservatives and natural ingredients commonly used in the food industry on the biofilm of Salmonella typhimurium. Methods: By adding different kinds and concentrations of scavengers during the culture process, the influence on the formation of biofilm was determined. The mature biofilm was soaked with various selected scavengers to evaluate the clearance effect under different concentrations of each substance. The metabolic activity of bacteria cells in the biofilm was determined by methylthiazolyldiphenyl-tetrazolium bromide(MTT) assay. And the number of viable bacteria was calculated by dilution plate coating method. Results: The disinfectant ethanol(50%), hydrogen peroxide(1%), benzalkonium chloride(0.6%), benzalkonium bromide(0.6%), and natural components carvol, cinnamaldehyde and thyme essential oil(1.0 μL/mL) could effectively inhibit the formation of S. typhimurium CDC3 and S. typhimurium ST34. Disinfectants detergent, hydrogen peroxide, natural ingredients(carvol, cinnamaldehyde and thyme essential oil) showed certain advantages in the removal of mature biofilm. Among them, the most ideal removal efficiency was hydrogen peroxide, which could reach about 90%, the maximum removal rate of detergent could reach 80%, and the essential oils of carvacrol, cinnamaldehyde and thyme could reach about 70%. The disinfectant ethanol, benzalkonium chloride and benzalkonium bromide, as well as the natural components carvol, cinnamaldehyde and thyme essential oil could significantly reduce the cell metabolic activity and the number of viable bacteria in biofilm, the number of viable bacteria in the biofilm could be reduced by 2 to 3 lg values. Conclusions: In contrast with the removal of mature biofilm, the addition of scavenging agent or natural ingredients at the early stage of cultivation made up for a more efficient control of the biofilm.