Enhancing the Bactericidal Effect of Electrolyzed Water on Listeria monocytogenes Biofilms Formed on Stainless Steel

Biofilms are potential sources of contamination to food in processing plants, because they frequently survive sanitizer treatments during cleaning. The objective of this research was to investigate the combined use of alkaline and acidic electrolyzed (EO) water in the inactivation of Listeria monocytogenes biofilms on stainless steel surfaces. Biofilms were grown on rectangular stainless steel (type 304, no. 4 finish) coupons (2 by 5 cm) in a 1:10 dilution of tryptic soy broth that contained a five-strain mixture of L. monocytogenes for 48 h at 25°C. The coupons with biofilms were then treated with acidic EO water or alkaline EO water or with alkaline EO water followed by acidic EO water produced at 14 and 20 A for 30, 60, and 120 s. Alkaline EO water alone did not produce significant reductions in L. monocytogenes biofilms when compared with the control. Treatment with acidic EO water only for 30 to 120 s, on the other hand, reduced the viable bacterial populations in the biofilms by 4.3 to 5.2 log CFU per coupon, whereas the combined treatment of alkaline EO water followed by acidic EO water produced an additional 0.3- to 1.2-log CFU per coupon reduction. The population of L. monocytogenes reduced by treatments with acidic EO water increased significantly with increasing time of exposure. However, no significant differences occurred between treatments with EO water produced at 14 and 20 A. Results suggest that alkaline and acidic EO water can be used together to achieve a better inactivation of biofilms than when applied individually.

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Behavior of Listeria monocytogenes in a Pseudomonas putida Biofilm on a Condensate-Forming Surface

Journal of Food Protection ◽

10.4315/0362-028x-67.2.322 ◽

2004 ◽

Vol 67 (2) ◽

pp. 322-327 ◽

Cited By ~ 42

Author(s):

ASHRAF N. HASSAN ◽

DAWN M. BIRT ◽

JOSEPH F. FRANK

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Pseudomonas Putida ◽

Microscopic Observation ◽

Pure Culture ◽

Extracellular Polymeric Substances ◽

Plate Count ◽

Free Surfaces ◽

Processing Plants ◽

Humidity Chamber

Listeria monocytogenes has been isolated from condensate-forming surfaces in food processing plants. The objective of this research was to observe the behavior of L. monocytogenes on condensate-covered stainless steel with a Pseudomonas putida biofilm. L. monocytogenes–containing biofilms, either with or without added chicken protein, were incubated in a high humidity chamber at 12°C to allow formation of condensate. Samples were analyzed for attached and unattached L. monocytogenes and total plate count periodically for 35 days. Samples were also taken for microscopic observation of Listeria and bacterial extracellular polymeric substances (EPS). L. monocytogenes attached in significantly greater numbers (>3-log difference) to surfaces with preexisting P. putida biofilms than to Pseudomonas-free surfaces. L. monocytogenes survived in the presence or absence of P. putida with no added nutrients for 35 days, with numbers of survivors in the range of 3 to 4 log CFU/cm2 in the presence of P. putida and less than 2.9 log CFU/cm2 in pure culture. Attached and unattached L. monocytogenes were at similar levels throughout the incubation under all conditions studied. The addition of protein to the biofilms allowed growth of L. monocytogenes in pure culture during the first 7 days of incubation. Numbers of L. monocytogenes were not affected by the presence of P. putida when protein was present. Unattached L. monocytogenes were at levels of 3.6 to 6.7 log CFU/cm2 on the protein-containing surfaces. Microscopic observation of the condensate-covered biofilms indicated that L. monocytogenes formed microcolonies embedded within an EPS matrix over a 28-day period. This research demonstrates that L. monocytogenes can survive on condensate-forming stainless steel in low and high nutrient conditions, with or without the presence of Pseudomonas biofilm. The Listeria can detach and, therefore, have the potential to contaminate product.

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Adsorption on stainless steel surfaces of biosurfactants produced by gram-negative and gram-positive bacteria: Consequence on the bioadhesive behavior of Listeria monocytogenes

Colloids and Surfaces B Biointerfaces ◽

10.1016/j.colsurfb.2006.04.016 ◽

2006 ◽

Vol 52 (2) ◽

pp. 128-137 ◽

Cited By ~ 54

Author(s):

Thierry Meylheuc ◽

Christophe Methivier ◽

Margareth Renault ◽

Jean-Marie Herry ◽

Claire-Marie Pradier ◽

...

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Gram Positive ◽

Gram Negative ◽

Gram Positive Bacteria ◽

Steel Surfaces

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Comparison of three neutralizing broths for environmental sampling of low levels of Listeria monocytogenes desiccated on stainless steel surfaces and exposed to quaternary ammonium compounds

BMC Microbiology ◽

10.1186/s12866-020-02004-1 ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Fengmin Li ◽

Zhihan Xian ◽

Hee Jin Kwon ◽

Jiyoon Yoo ◽

Laurel Burall ◽

...

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Quaternary Ammonium ◽

Storage Conditions ◽

Ammonium Compound ◽

Environmental Sampling ◽

High Concentration ◽

Environmental Test ◽

Steel Surfaces ◽

Low Levels

Abstract Background An effective environmental sampling method involves the use of a transport/neutralizing broth with the ability to neutralize sanitizer residues that are collected during sampling and to maintain viability of stressed Listeria monocytogenes (Lm) cells. Results We applied Lm onto stainless steel surfaces and then subjected Lm to desiccation stress for 16–18 h at room temperature (RT, 21–24 °C). This was followed by the subsequent application of Whisper™ V, a quaternary ammonium compound (QAC)-based sanitizer, diluted to 400 ppm and 8000 ppm of active quat, for 6 h. We then sampled Lm with sponges pre-moistened in three transport broths, Dey/Engley (D/E) broth, Letheen broth and HiCap™ broth, to generate environmental samples that contained sanitizer residues and low levels of stressed Lm, which were subsequently analyzed by an enrichment-based method. This scheme conformed with validation guidelines of AOAC International by using 20 environmental test portions per broth that contained low levels of Lm such that not all test portions were positive (i.e., fractional positive). We showed that D/E broth, Letheen broth and HiCap™ broth performed similarly when no quat or 400 ppm of quat was applied to the Lm contaminating stainless steel surfaces. However, when 8000 ppm of quat was applied, Letheen broth did not effectively neutralize the QAC in the samples. These comparisons were performed on samples stored under three conditions after collection to replicate scenarios of sample transport, RT for 2 h, 4 °C for 24 h and 4 °C for 72 h. Comparisons under the three different scenarios generally reached the same conclusions. In addition, we further demonstrated that storing Letheen and HiCap™ broths at RT for two months before sampling did not reduce their capacity to neutralize sanitizers. Conclusions We developed a scheme to evaluate the ability of transport broths to neutralize QAC sanitizers. The three transport broths performed similarly with a commonly used concentration of quat, but Letheen broth could not effectively neutralize a very high concentration of QAC. The performance of transport broths was not significantly affected under the assessed pre-sampling and post-sampling storage conditions.

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Nanoengineered Superhydrophobic Surfaces to Prevent Adhesion of Listeria monocytogenes for Improved Food Safety

Transactions of the ASABE ◽

10.13031/trans.13934 ◽

2020 ◽

Vol 63 (5) ◽

pp. 1401-1407

Author(s):

Bog Eum Lee ◽

Youngsang You ◽

Won Choi ◽

Eun-mi Hong ◽

Marisa M. Wall ◽

...

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Biofilm Formation ◽

Electrochemical Etching ◽

Contact Angles ◽

Bacterial Attachment ◽

Superhydrophobic Surfaces ◽

List Type ◽

Ptfe Film ◽

Steel Surfaces

HighlightsNanoporous superhydrophobic surfaces were fabricated using electrochemical etching and Teflon coating.Adhesion of Listeria monocytogenes to the nanoengineered stainless steel surfaces was reduced.Self-cleanable food-contact surfaces prevent bacterial attachment and subsequent biofilm formation.Abstract. Bacterial attachment on solid surfaces and subsequent biofilm formation is a significant problem in the food industry. Superhydrophobic surfaces have potential to prevent bacterial adhesion by minimizing the contact area between bacterial cells and the surface. In this study, stainless steel-based superhydrophobic surfaces were fabricated by manipulating nanostructures with electrochemical etching and polytetrafluoroethylene (PTFE) film. The formation of nanostructures on stainless steel surfaces was characterized by field emission scanning electron microscopy (FESEM). The stainless steel surfaces etched at 10 V for 5 min and at 10 V for 10 min with PTFE deposition resulted in average water contact angles of 154° ±4° with pore diameters of 50 nm. In addition, adhesion of Listeria monocytogenes was decreased by up to 99% compared to the bare substrate. These findings demonstrate the potential for the development of antibacterial surfaces by combining nanoporous patterns with PTFE films. Keywords: Electrochemical etching, PTFE, Nanoengineered surface, L. monocytogenes, Superhydrophobic.

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Effect of Growth Nutrients on Attachment of Listeria monocytogenes To Stainless Steel

Journal of Food Protection ◽

10.4315/0362-028x-57.8.720 ◽

1994 ◽

Vol 57 (8) ◽

pp. 720-724 ◽

Cited By ~ 29

Author(s):

KWANG Y. KIM ◽

JOSEPH F. FRANK

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Cell Surface ◽

Minimal Medium ◽

Cell Attachment ◽

Chloride Concentration ◽

Fold Increase ◽

Hydrolyzed Protein ◽

Steel Surfaces ◽

Attachment Ability

Listeria monocytogenes cells grown in chemically defined minimal medium (D10), tryptic soy broth (TSB), and modifications of these media were used to determine the effect of growth nutrients on attachment ability. Stainless steel surfaces were submerged in various cell suspensions at 21°C for 4 h, and the numbers of attached cells were compared. Cells grown in D10 showed approximately 50-fold higher attachment than those grown in TSB. Addition of components of D10 to TSB did not affect the attachment ability of cells grown in TSB. The only modifications of D10, which affected attachment ability were a 10-fold increase of ammonium chloride concentration and a 1/10 reduction in iron, both of which resulted in decreases in attachment ability to one third of the D10 control. Replacement of glucose in D10 with mannose, cellobiose, fructose or trehalose did not effect cell attachment. Replacement of nitrogen components in D10 with tryptone decreased cell attachment to the equivalent level of cells grown in TSB. The reduced attachment ability of TSB-grown cells was not the result of hydrolyzed protein absorbing to the cell surface.

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Effectiveness of a Novel Rechargeable Polycationic N-Halamine Antibacterial Coating on Listeria monocytogenes Survival in Food Processing Environments

Journal of Food Protection ◽

10.4315/jfp-20-084 ◽

2020 ◽

Vol 83 (11) ◽

pp. 1974-1982

Author(s):

GERARDO MEDINA ◽

HARSHITA CHAUDHARY ◽

YANG QIU ◽

YUCHEN NAN ◽

ARGENIS RODAS-GONZÁLEZ ◽

...

Keyword(s):

Stainless Steel ◽

Listeria Monocytogenes ◽

Surface Condition ◽

Organic Load ◽

Log Reduction ◽

Food Contact Surfaces ◽

Roast Beef ◽

Steel Surfaces ◽

The Difference ◽

Steel Coupon

ABSTRACT The goal of this research was to evaluate the efficacy of a novel rechargeable nonleaching polycationic N-halamine coating applied to stainless steel food contact surfaces to reduce Listeria monocytogenes contamination on ready-to-eat (RTE) foods. Four L. monocytogenes strains were inoculated onto the charged (C; chlorine activated) or noncharged (NC) N-halamine–coated steel coupon surfaces that were either intact or scratched. After inoculation, test surfaces were incubated at 2, 10, and 25°C for 0, 48, and 72 h. L. monocytogenes transfer from coated adulterated surfaces to RTE meat (beef sausages and roast beef) was also tested at 2°C. L. monocytogenes on both intact-C and scratched-C surfaces was significantly reduced at all temperatures; however, in the presence of organic material, these coatings were more effective for reducing L. monocytogenes at 2 and 10°C than at 25°C (P < 0.05). In contrast, on NC intact and scratched surfaces, reduction at 25°C increased (P < 0.05), decreasing the difference in L. monocytogenes levels between charged and noncharged intact and scratched surfaces at this temperature. Overall, greater L. monocytogenes reduction was achieved on intact-C and scratched-C (4.1 ± 0.19 log CFU/cm2) than on intact-NC and scratched-NC (2.3 ± 0.19 log CFU/cm2) surfaces at all temperatures (P < 0.05). The combination of surface condition and chlorine with coupons exposed for 2 h at 2°C in the presence of an organic load (50% meat purge) did not significantly affect the bactericidal efficacy of the N-halamine coating. Regarding transfer to RTE meat, an overall 3.7-log reduction in L. monocytogenes was observed in sausages and roast beef. These findings suggest that a novel rechargeable N-halamine coating on stainless steel surfaces can inactivate L. monocytogenes. HIGHLIGHTS

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