Current sanitation methods in the food industry are not always sufficient for prevention or dispersal of Listeria
monocytogenesbiofilms. Here, we determined if prevention of adherence or dispersal of existing biofilms could
occur if biofilm matrix components were disrupted enzymatically. Addition of DNase during biofilm formation
reduced attachment (b50% of control) to polystyrene. Treatment of established 72 h biofilms with 100 μg/ml
of DNase for 24 h induced incomplete biofilm dispersal, withb25% biofilm remaining compared to control. In
contrast, addition of proteinase K completely inhibited biofilm formation, and 72 h biofilms—including those
grown under stimulatory conditions—were completely dispersed with 100μg/ml proteinase K. Generallyregarded-as-safe proteases bromelain and papain were less effective dispersants than proteinase K. In a time
course assay, complete dispersal ofL. monocytogenesbiofilms from both polystyrene and type 304H food-grade
stainless steel occurred within 5 min at proteinase K concentrations above 25μg/ml. These data confirm that
both DNA and proteins are required forL. monocytogenesbiofilm development and maintenance, and that
these components of the biofilm matrix can be targeted for effective prevention and removal of biofilms.