title: Antibiofilm effect of plant derived antimicrobials on Listeria monocytogenes.
abstract: The present study investigated the efficacy of sub-inhibitory concentrations (SICs, concentrations not inhibiting bacterial growth) and bactericidal concentrations (MBCs) of four, generally recognized as safe (GRAS), plant-derived antimicrobials (PDAs) in inhibiting Listeria monocytogenes (LM) biofilm formation and inactivating mature LM biofilms, at 37, 25 and 4 °C on polystyrene plates and stainless-steel coupons. In addition, the effect of SICs of PDAs on the expression of LM genes critical for biofilm synthesis was determined by real-time quantitative PCR. The PDAs and their SICs used for inhibition of biofilm were trans-cinnamaldehyde (TC 0.50, 0.75 mM), carvacrol (CR 0.50, 0.65 mM), thymol (TY 0.33, 0.50 mM), and eugenol (EG 1.8, 2.5 mM), whereas the PDA concentrations used for inactivating mature biofilms were 5.0 and 10.0 mM (TC, CR), 3.3 and 5.0 mM (TY), 18.5 and 25.0 mM (EG). All PDAs inhibited biofilm synthesis and inactivated fully formed LM biofilms on both matrices at three temperatures tested (P < 0.05). Real-time quantitative PCR data revealed that all PDAs down-regulated critical LM biofilm-associated genes (P < 0.05). Results suggest that TC, CR, TY, and EG could potentially be used to control LM biofilms in food processing environments, although further studies under commercial settings are necessary.
authors.affiliation: Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA.
authors.forename: Abhinav
authors.initials: A
authors.lastname: Upadhyay
authors.forename: Indu
authors.initials: I
authors.lastname: Upadhyaya
authors.forename: Anup
authors.initials: A
authors.lastname: Kollanoor-Johny
authors.forename: Kumar
authors.initials: K
authors.lastname: Venkitanarayanan
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry*; D017365:Spices / Q000032:analysis*; D013193:Stainless Steel / Q000032:analysis
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D013193:Stainless Steel