Combined effect of benzalkonium chloride and ultrasound againstListeria monocytogenesbiofilm on plastic surface

Abstract

Significance and Impact of the Study: Listeria monocytogenes is capable of adhering and forming biofilm on inert surfaces such as plastics. Biofilms are more resistant to disinfectants compared to planktonic cells, and this makes their elimination from food processing facilities a big challenge. Moreover, the emergence of resistant to disinfectants bacteria clearly shows that new biofilm control strategies are required. Among new strategies, the ultrasound treatment attracts attention as a nonchemical and environmentally friendly technology. This study demonstrated that the combination of ultrasound and benzalkonium chloride is a feasible strategy for removal of L. monocytogenes biofilms from plastic food-contact surfaces. AbstractThis study was performed to evaluate the effectiveness of benzalkonium chloride combined with ultrasound in eliminating Listeria monocytogenes biofilm from polystyrene surface. The test strain of L. monocytogenes, previously classified as strong biofilm producer, was grown to form biofilm in tryptic soy broth at 20°C for 6 days in polystyrene specimen containers. The biofilms formed on surface of containers were treated with ultrasound alone, benzalkonium chloride (100 and 400 mg l À1 ) alone and their combination for three different exposure times (1, 5 and 15 min) at room temperature. Sonication was performed using an ultrasound bath at a constant ultrasound frequency of 35 kHz. After treatments, levels of biofilm biomass and viable cells in biofilm were determined using crystal violet staining and XTT assays, respectively. The combined treatment of ultrasound and benzalkonium chloride resulted in significant (P < 0Á05) more decrease in the level of viable cells in the L. monocytogenes biofilm compared to individual treatments of benzalkonium chloride. Our results suggest that the combination of benzalkonium chloride with ultrasound is useful approach for the elimination of L. monocytogenes biofilms from plastic surfaces.

Listeria monocytogenes: A Dangerous and Insidious Pathogen in Seafood

“…Recently, Torlack and Sert have been examining the efficacy of benzalkonium chloride and ultrasonic waves to inactivate biofilm on plastic surfaces. Their results highlight that to inactivate the bacterial cells that make up the biofilm, a combined use of benzalkonium chloride and ultrasonic waves is much more effective than any single treatment (Torlack and Sert 2013). Another study, instead, focused on the effects of ozone and open-air factor (OAF) on L. monocytogenes biofilms formed on stainless steel, polypropylene and granite (Nicholas et al 2013).…”

Inhibition strategies of Listeria monocytogenes biofilms—current knowledge and future outlooks

“…Chlorine, H 2 O 2 , and peroctanoic acid Exposure of sessile cells of L. monocytogenes to chlorine, hydrogen peroxide and peroctanoic acid showed significant reduction in the cells [163,164] Peracetic acid Peracetic acid acts as an antibiofilm agent on exposure to biofilm formed on stainless steel [165] Chlorine and thiamine dilaurylsulfate Both chemical inhibit biofilm formation, but a significant inhibition occurred in combined treatment [166] Chlorinated-alkaline solution The solution showed effectiveness on the removal of biofilm formed at 4°C on a stainless steel, brick, and conveyor material in the presence of ready-to-eat meat residue [167] Nisin + organic salts such as sodium acetate Inactivation of biofilm formed on fresh cut tomato occurred in the presence of nisin-sodium acetate (5%) [168] Titanium dioxide and UV-light irradiation Titanium dioxide photocatalysts had inhibitory effect on sessile cells of L. monocytogenes [169] Chitosan Chitosan and its enzymatically hydrolyzed product possess antimicrobial and antibiofilm effect [170] Benzalkonium chloride This showed minimal effect on mixed-culture sessile communities of L. monocytogenes [124] Benzalkonium chloride and ultrasound Combined treatment effectively remove the biofilm formed on plastic surfaces [88] Sodium hypochlorite, hydrogen peroxide, iodophor, and benzalkonium chloride These chemical sanitizers along with steam are potent biofilm inhibitors of L. monocytogenes [171] Synthetic cationic peptide 1037 Reduce biofilm formation significantly (>50%) and lead to cell death in biofilms [122] Puroindoline and hordoindoline tryptophan rich domain cationic peptides Synthetic tryptophan rich peptides act as both antibiofilm and sporicidal activity [172] κ-Casein macropeptide from milk protein κ-casein macropeptide possess inhibitory effect on biofilm formed by L. monocytogenes and repressed the gene responsible for adherence at 0.4 mg ml −1 [135] Sugar fatty acid esters with long chain fatty acid residues (C14-16)…”

Biosurfactants in Food

“…It may be essential to use a larger amount of disinfectant than the prescribed concentration in food formulation areas to confi rm biocide concentrations (Norwood and Gilmour 2000 ;Ortega-Morales et al 2013 ). That various biofi lm-forming microorganisms have established resistance to biocides notably shows that novel biofi lm prevention approaches are required (Torlak and Sert 2013 ;Ortega-Morales et al 2013 ).…”