Inhibition and Inactivation of Listeria monocytogenes and Escherichia coli O157:H7 Colony Biofilms by Micellar-Encapsulated Eugenol and Carvacrol

Abstract

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.

Natural plant products inhibits growth and alters the swarming motility, biofilm formation, and expression of virulence genes in enteroaggregative and enterohemorrhagic Escherichia coli

“…However rifaximin promoted development (at all subletal concentrations) in EHEC O157:H7 and (at 75% MBC) in EAEC O104:H4. Application of micellar-encapsulated carvacrol at various concentrations has been inhibitory against surface growth of E. coli O157:H7 (P erez-Conesa et al, 2006). In our study, carvacrol at 75% MBC also reduced biofilm formation.…”

Horizontal transfer of non-conjugative plasmid in colony biofilm of Escherichia coli on food-based media

“…In addition, many lines of evidence have revealed that biofilm cells often exhibit unique physiological characteristics distinct from those of planktonic cells in liquid culture (Davey and O'Toole 2000;Romeo 2008;Annous et al 2009). Consistent with these expectations, we recently found that spontaneous lateral transfer of non-conjugative plasmids occurs in a colony biofilm [a type of biofilm that is formed on the air-solid surface (Mah et al 2003;Carmen et al 2004;Branda et al 2005;Perez-Conesa et al 2006)] of E. coli grown on common laboratory media, such as LB agar (Maeda et al 2006).…”

Cinnamon essential oil and cinnamaldehyde in the control of bacterial biofilms formed on stainless steel surfaces

“…However, in the Wrst stage of this study and in a part of the second stage (single-species bioWlm), sessile cells of L. monocytogenes were more resistant to C. cassia EO and cinnamaldehyde than the cells of the gram-negative species used (EPEC). Similarly, Perez-Conesa et al [37] evaluated the antimicrobial eYcacy of encapsulated carvacrol and eugenol on strains of L. monocytogenes and E. coli O157: H7 in bioWlms and found that the gram-negative bacteria were more sensitive to the antimicrobial agents compared to the gram-positive bacteria. According to the studies of Rieu et al [38], van der Veen and Abee [39] and van der Veen and Abee [40], bioWlms formed by L. monocytogenes under conditions of constant Xow may have diVerent architecture and greater expression of genes related to the cellular stress response, which can cause an increase in resistance to antibacterial agents.…”