Biofilms - drug effects, Gentian Violet, Food Contamination - prevention & control, Sonication, Disinfectants - pharmacology, Polystyrenes, Biofilms - growth & development, Disinfection - methods, Benzalkonium Compounds - pharmacology, Listeria monocytogenes - growth & development, Microbial Viability, Listeria monocytogenes - drug effects