title: Reduction of Listeria monocytogenes biofilms on stainless steel and polystyrene surfaces by essential oils.
abstract: Plant-derived essential oils were tested for their ability to eliminate biofilms of Listeria monocytogenes on polystyrene and stainless steel surfaces. Various concentrations of essential oils were tested with different contact times on biofilms of various ages. Preliminarily  screening of nine essential oils and related phenolic compounds in a disk diffusion assay revealed that thyme oil, oregano oil, and carvacrol had the highest antimicrobial activity. Further screening of these three compounds against 21 L. monocytogenes strains representing all 13 serotypes  indicated some strain-specific variations in antimicrobial activity. For 1-day-old biofilms of mixed L. monocytogenes strains produced at 22°C on polystyrene microtiter plates, only 0.1% concentrations of thyme oil, oregano oil, and carvacrol were needed to eliminate 7 log CFU per  well. On the stainless steel coupons, a 0.5% concentration of these compounds was adequate to completely eliminate 4-day-old biofilms at 7 log CFU per coupon. Our findings indicate that these compounds are potential candidates for elimination of L. monocytogenes biofilms on stainless steel and polystyrene surfaces.
authors.affiliation: Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, MS 39762, USA.
authors.forename: Monil A
authors.initials: MA
authors.lastname: Desai
authors.forename: Kamlesh A
authors.initials: KA
authors.lastname: Soni
authors.forename: Ramakrishna
authors.initials: R
authors.lastname: Nannapaneni
authors.forename: M Wes
authors.initials: MW
authors.lastname: Schilling
authors.forename: Juan L
authors.initials: JL
authors.lastname: Silva
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D015169:Colony Count, Microbial; D004203:Disinfection / Q000379:methods; D004866:Equipment Contamination / Q000517:prevention & control; D005506:Food Contamination / Q000517:prevention & control; D006801:Humans; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000502:physiology*; D009822:Oils, Volatile / Q000494:pharmacology*; D011137:Polystyrenes; D013193:Stainless Steel
chemical_list: D000900:Anti-Bacterial Agents; D009822:Oils, Volatile; D011137:Polystyrenes; D013193:Stainless Steel