Many foodborne pathogens including E. coli O157:H7 and Salmonella enterica can develop biofilms on contact surfaces at meat processing plants. Due to the high tolerance of the biofilm cells associated with the 3-dimensional biofilm structure and the well-expressed bacterial polymeric extracellular substances (EPS), it is a real challenge to completely inactivate and remove mature biofilms as well as further prevent biofilm reoccurrence and pathogen survival. We evaluated the effectiveness of consecutive treatments by repeatedly applying a multicomponent sanitizer, based on the functional mechanism by synergistic combination of hydrogen peroxide and quaternary ammonia compounds, against biofilms by E. coli O157:H7 and Salmonella strains. Biofilms were treated with 2.5%, 5%, or 10% of the sanitizer applied as foam or liquid solution. The sanitizer at all concentrations significantly reduced the amount of viable biofilm cells as enumerable bacteria were only detected after low concentration treatments (2.5% or 5%) with short exposure periods. Treatments with high concentrations (5% or 10%) of the sanitizer, multiple consecutive treatments and sufficient exposure time effectively controlled pathogen post-sanitization survival. Examination with a scanning electron microscope showed that treatment with the sanitizer at 5% strength significantly dissolved the connecting EPS matrix and removed most of the biofilm matrix. No intact biofilm structure was detected after the 10% sanitizer treatment, instead, scattered individual bacteria with visibly altered cell morphology were observed. The treated bacteria exhibited indented and distorted shapes with shortened cell length and increased surface roughness, indicating severe cell injury and death. Our observations indicated that consecutive treatments with the multicomponent sanitizer was effective in inactivating E. coli O157:H7 and Salmonella enterica biofilms and preventing pathogen reoccurrence.
KSWFoodWorld
FoodWorld 