Inhibition and inactivation of Listeria monocytogenes and Escherichia coli O157:H7 colony biofilms by micellar-encapsulated eugenol and carvacrol.
The antimicrobial efficacy of carvacrol and eugenol, two essential oil compounds, encapsulated in a micellar nonionic surfactant solution on four strains of Listeria monocytogenes (Scott A, 101, 108, and 310) and four strains of Escherichia coli O157:H7 (H1730, E0019, F4546, and 932) growing as colony biofilms was investigated. Carvacrol and eugenol were encapsulated in Surfynol 485W at concentrations ranging from 0.3 to 0.9% (wt/wt) at a surfactant concentration of 5% (wt/wt). Colony biofilms were grown on polycarbonate membranes resting on agar plates containing antimicrobial formulations. Cells were enumerated after 0, 3, 6, 9, 24, 48, and 72 h of incubation. Colony biofilms of all E. coli O157:H7 strains were more sensitive to both antimicrobial systems than L. monocytogenes strains. Surface-grown E. coli O157:H7 viable cell numbers decreased below detectable levels after exposure to encapsulated essential oil compounds for > 3 h at all tested concentrations, except for E. coli O157:H7 F4546, which grew slowly in the presence of < 0.5% (wt/wt) eugenol. L. monocytogenes Scott A and 101 were more resistant to eugenol than carvacrol at sublethal concentrations (< 0.5% [wt/wt]). Carvacrol was effective at any concentration against L. monocytogenes 108, whereas concentrations of > 0.5% (wt/wt) eugenol were required for inactivation. L. monocytogenes 310 was equally sensitive to both essential oil compounds. Results suggest that surfactant-encapsulated generally recognized as safe essential oil compounds may offer a new means to control the growth of food pathogens such as E. coli O157:H7 and L. monocytogenes on food contact surfaces.
Pérez-Conesa
D
D
Department of Food Science, University of Massachusetts, 100 Holdsworth Way, Amherst, Massachusetts 01003, USA.
McLandsborough
L
L
Weiss
J
J
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000254:growth & development; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D000081007:Cymenes; D004305:Dose-Response Relationship, Drug; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000502:physiology; D005054:Eugenol; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000502:physiology; D008823:Micelles; D008826:Microbial Sensitivity Tests; D039821:Monoterpenes; D013997:Time Factors
D000900:Anti-Bacterial Agents; D000081007:Cymenes; D008823:Micelles; D039821:Monoterpenes; D005054:Eugenol; C073316:carvacrol