title: Inhibition and inactivation of Salmonella typhimurium biofilms from polystyrene and stainless steel surfaces by essential oils and phenolic constituent carvacrol.
abstract: Persistence of Salmonella biofilms within food processing environments is an important source of Salmonella contamination in the food chain. In this study, essential oils of thyme and oregano and their antimicrobial phenolic constituent carvacrol were evaluated for their  ability to inhibit biofilm formation and inactivate preformed Salmonella biofilms. A crystal violet staining assay and CFU measurements were utilized to quantify biofilm cell mass, with evaluating factors such as strain variation, essential oil type, their concentrations, exposure time,  as well as biofilm formation surface. Of the three Salmonella strains, Salmonella Typhimurium ATCC 23564 and Salmonella Typhimurium ATCC 19585 produced stronger biofilms than Salmonella Typhimurium ATCC 14028. Biofilm formation by different Salmonella strains  was 1.5- to 2-fold higher at 22°C than at 30 or 37°C. The presence of nonbiocidal concentrations of thyme oil, oregano oil, and phenolic carvacrol at 0.006 to 0.012% suppressed Salmonella spp. biofilm formation 2- to 4-fold, but could not completely eliminate biofilm formation.  There was high correlation in terms of biofilm inactivation, as determined by the crystal violet-stained optical density (at a 562-nm wavelength) readings and the viable CFU counts. Reduction of biofilm cell mass was dependent on antimicrobial concentration. A minimum concentration of  0.05 to 0.1% of these antimicrobial agents was needed to reduce a 7-log CFU biofilm mass to a nondetectable level on both polystyrene and stainless steel surfaces within 1 h of exposure time.
authors: Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Mississippi State, MS 39762, USA.
authors: Kamlesh A
authors: KA
authors: Soni
authors: Ademola
authors: A
authors: Oladunjoye
authors: Ramakrishna
authors: R
authors: Nannapaneni
authors: M Wes
authors: MW
authors: Schilling
authors: Juan L
authors: JL
authors: Silva
authors: Benjy
authors: B
authors: Mikel
authors: R Hartford
authors: RH
authors: Bailey
mesh_terms: D001422:Bacterial Adhesion / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development*; D000081007:Cymenes; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005511:Food Handling / Q000379:methods; D039821:Monoterpenes / Q000494:pharmacology; D009822:Oils, Volatile / Q000494:pharmacology; D011137:Polystyrenes; D012486:Salmonella typhimurium / Q000502:physiology*; D013193:Stainless Steel
chemical_list: D000081007:Cymenes; D039821:Monoterpenes; D009822:Oils, Volatile; D011137:Polystyrenes; D013193:Stainless Steel; C073316:carvacrol