scholarly journals Effect of Environmental Stress on the Ability of Listeria monocytogenes Scott A To Attach to Food Contact Surfaces

1998 ◽  
Vol 61 (10) ◽  
pp. 1293-1298 ◽  
Author(s):  
L. MICHELE SMOOT ◽  
MERLE D. PIERSON
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Cell Growth ◽  
Cell Populations ◽  
Sterile Phosphate Buffer ◽  
Food Contact Surfaces ◽  
Alkaline Conditions ◽  
Ph Conditions ◽  
Growth Ph ◽  
Holding Temperature

Attachment of Listeria monocytogenes Scott A to Buna-N rubber and stainless Steel under different temperature and pH conditions at the time of cell growth or at the time of attachment was investigated. AU experiments were conducted using sterile phosphate buffer to avoid cell growth during exposure to the test surfaces. Numbers of attached cells increased with increasing attachment temperature (10 to 45°C) and exposure time for both test surfaces. Maximum levels of attached cells were obtained when cell growth occurred at 30°C. Downward, but not upward, shifts in the cell suspension holding temperature prior to attachment to Buna-N rubber resulted in reduced adhered cell populations. Maximum levels of adhered cells to Buna-N rubber were not affected by adjustments of the attachment medium pH between 4 and 9. However, after short contact times (i.e., less than 30 min), levels of attached cells were lower when attachment occurred under alkaline conditions. Growth pH was also found to affect the levels of adhered cell populations to Buna-N rubber. L. monocytogenes Scott A attached to stainless Steel at higher levels for all temperature and pH parameters evaluated in this study.

Influence of Environmental Stress on the Kinetics and Strength of Attachment of Listeria monocytogenes Scott A to Buna-N Rubber and Stainless Steel

1998 ◽  
Vol 61 (10) ◽  
pp. 1286-1292 ◽  
Author(s):  
L. MICHELE SMOOT ◽  
MERLE D. PIERSON
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Growth Temperature ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Model Systems ◽  
Test Surface ◽  
Alkaline Conditions ◽  
Temperature And Growth ◽  
Growth Ph

Attachment and detachment of Listeria monocytogenes Scott A to Buna-N rubber and stainless Steel under varying conditions of temperature and pH were investigated using model systems. Numbers of attached cells increased with increasing attachment temperature (10 to 45°C) and time (up to 120 min) for both test surfaces. Compared to Buna-N rubber, the rate of attachment to stainless Steel was markedly more rapid for all temperature and pH conditions studied and could not be calculated. Rate of attachment to Buna-N rubber was found to be significantly lower when cells were attached at 10°C. Growth temperature did not significantly affect rates of adhesion to Buna-N rubber. Altering the medium pH during attachment between 4 and 9 demonstrated that rates of adhesion were slower under alkaline conditions. Growth pH was also found to significantly affect rates of attachment to Buna-N rubber. Detachment of cells adhered to Buna-N rubber was significantly affected by growth temperature but not growth pH. Significant differences in detachment were also found between Buna-N rubber and stainless Steel, inferring stronger attachment to Buna-N rubber. Cell surface hydrophobicity was found to be affected by both growth temperature and growth pH. However, changes in hydrophobicity could not be correlated to differences in rates of attachment. Addition of 0.01% trypsin to the attachment medium during cell exposure to either test surface resulted in a 99.9% reduction in the adhered cell population when compared to Controls. This would suggest that proteins play a role in the initial attachment process of L. monocytogenes.

Inactivation of Surface-adherent Listeria monocytogenes Hypochlorite and Heat

1991 ◽  
Vol 54 (1) ◽  
pp. 4-6 ◽  
Author(s):  
SHIN-HO LEE ◽  
JOSEPH F. FRANK
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Cell Population ◽  
Incubation Time ◽  
Cell Populations ◽  
Adherent Cell ◽  
Adherent Cells ◽  
D Cells

Inactivation by hypochlorite of Listeria monocytogenes cells adherent to stainless steel was determined. Adherent cell populations were prepared by incubating stainless steel slides with a 24 h culture of L. monocytogenes for 4 h at 21°C. Adherent microcolonies were prepared by growing L. monocytogenes on stainless steel slides submerged in a 1:15 dilution of tryptic soy broth at 21°C. The slides were then rinsed and transferred to fresh sterile broth every 2 d with a total incubation time of 8 d. Although the 4 h and 8 d adherent populations were at similar levels, 8 d adherent cells were over 100 times more resistant than the 4 h adherent cell population when exposed to 200 ppm hypochlorite for 30 s. When stainless steel slides containing adherent cells were heated at 72°C both adherent cell populations were inactivated after 1 min. Detectable numbers of L. monocytogenes remained on stainless steel slides after treatment at 65°C for 3 min when adherent 8 d cells were tested but not when adherent 4 h cells were used.

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

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

scholarly journals The Listeria monocytogenes Homolog of the Escherichia coli era Gene Is Involved in Adhesion to Inert Surfaces

2007 ◽  
Vol 73 (23) ◽  
pp. 7789-7792 ◽  
Author(s):  
Frédéric Auvray ◽  
Danielle Chassaing ◽  
Cécile Duprat ◽  
Brigitte Carpentier
Keyword(s):  
Escherichia Coli ◽  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Growth Defect ◽  
Cell Populations ◽  
Lower Growth ◽  
E Coli ◽  
Attached Cell ◽  
Dimethylammonium Chloride ◽  
Inert Surfaces

ABSTRACT Two transposon-insertional mutants of Listeria monocytogenes showing smaller viable surface-attached cell populations after disinfection with N,N-didecyl-N,N-dimethylammonium chloride were identified. In both mutants, transposon Tn917-lac was found to be inserted into the same gene, lmo1462, which is homologous to the essential Escherichia coli era gene. Both L. monocytogenes lmo1462-disrupted mutants displayed lower growth rates, as was also shown for several E. coli era mutants, and the lmo1462 gene was able to complement the growth defect of an E. coli era mutant. We showed that the disruption of lmo1462 decreased the ability of L. monocytogenes cells to adhere to stainless steel. Our results suggest that this era-like gene is involved in adhesion and contributes to the presence of L. monocytogenes on surfaces.

Comparison of Sampling Procedures for Recovery of Listeria monocytogenes from Stainless Steel Food Contact Surfaces

2012 ◽  
Vol 75 (6) ◽  
pp. 1077-1082 ◽  
Author(s):  
DIEGO GÓMEZ ◽  
AGUSTÍN ARIÑO ◽  
JUAN J. CARRAMIÑANA ◽  
CARMINA ROTA ◽  
JAVIER YANGÜELA
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Cost Effective ◽  
Sampling Procedure ◽  
Human Origin ◽  
Sampling Device ◽  
Food Contact ◽  
Food Contact Surfaces ◽  
Contact Surfaces ◽  
Sampling Procedures

A number of techniques exist for microbiological sampling of food processing environments in food industries. In the present study the efficacies of nine sampling procedures for the recovery of Listeria monocytogenes from food contact surfaces, including a new sampling device consisting of a miniroller, were evaluated and compared. A stainless steel table was inoculated with L. monocytogenes strain 935 (serovar 4b, human origin) and L. monocytogenes strain 437/07 (serovar 1/2b, food origin), at 105 CFU/100 cm2. L. monocytogenes strain 935 was best recovered with the minirollers (recovery of up to 6.27%), while poor recoveries (<0.30%) were obtained with the towel (one-ply composite tissue), alginate swab, metallic swab, and Petrifilm methods. In the case of L. monocytogenes strain 437/07 the replicate organism detection and counting (RODAC) ALOA contact plates yielded the best recoveries (4.15%), followed by the minirollers (up to 1.52%). Overall, recovery percentages with the minirollers were higher with stomacher homogenization than with Vibromatic agitation. The recovery percentages obtained for the Listeria strain of human origin were higher than those obtained with the food strain for all sampling procedures except Petrifilm and RODAC ALOA. With the miniroller device coated with wool fiber, the recovery of L. monocytogenes can be improved from 2 to 17 times over recoveries obtained with the sponge and cotton swab. This is the first report of a miniroller device for microbiological sampling in the available literature. The novel sampling procedure is convenient to apply on surfaces, is cost-effective, and results in better recovery of L. monocytogenes than do the conventional methods.

Growth Media and Surface Conditioning Influence the Adherence of Pseudomonas fragi, Salmonella typhimurium, and Listeria monocytogenes Cells to Stainless Steel

1997 ◽  
Vol 60 (9) ◽  
pp. 1034-1037 ◽  
Author(s):  
SCOTT K. HOOD ◽  
EDMUND A. ZOTTOLA
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Skim Milk ◽  
Epifluorescence Microscopy ◽  
Growth Media ◽  
Pseudomonas Fragi ◽  
Acridine Orange Staining ◽  
Surface Conditioning ◽  
Food Contact Surfaces

Microorganisms have been shown to adhere to food-contact surfaces and may provide a route for the contamination of processed food. To better understand this phenomenon, the effects of growth media and surface conditioning on the adherence of Pseudomonas fragi, Salmonella typhimurium and Listeria monocytogenes cells to stainless steel were studied. The microorganisms were grown in tryptic soy broth (TSB), 1% reconstituted skim milk (RSM) and RSM with 1% sucrose (RSM + S). Stainless-steel surfaces were conditioned by immersion in growth media for 1 h and then were rinsed in phosphate-buffered saline (PBS) prior to the adherence assay. After growing in each medium, cells were harvested, resuspended in PBS, and then allowed to contact the stainless steel for 30 min. Adherence was quantified by acridine orange-staining the cells and viewing under epifluorescence microscopy. Growth media had little influence on adherence to stainless steel that had not been preconditioned. P. fragi and L. monocytogenes cells adhered in the highest numbers when grown in RSM plus sucrose. S. typhimurium cells showed the highest level of adherence when grown in TSB. Analysis of variance yielded P values of less than 0.01, indicating that both growth media and surface conditioning were significant in the level of adherence observed.

Removal of Listeria monocytogenes Biofilms from Stainless Steel by Use of Ultrasound and Ozone

2009 ◽  
Vol 72 (6) ◽  
pp. 1306-1309 ◽  
Author(s):  
ADAM R. BAUMANN ◽  
SCOTT E. MARTIN ◽  
HAO FENG
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Phosphate Buffer ◽  
Combined Treatment ◽  
Potassium Phosphate ◽  
Potassium Phosphate Buffer ◽  
Power Ultrasound ◽  
Biofilm Removal ◽  
Food Contact Surfaces ◽  
Contact Surfaces

The objective of this study was to determine the efficacy of power ultrasound and ozonation used individually, and in tandem, for the removal of Listeria monocytogenes biofilms from stainless steel chips. Stainless steel chips were inoculated with L. monocytogenes. Power ultrasound (20 kHz, 100% amplitude, 120 W) was applied for 30 or 60 s at a distance of 2.54 cm from a biofilm chip while it was submerged in 250 ml of sterile potassium phosphate buffer (pH 7.0). Ozone was cycled through the 250 ml of potassium phosphate buffer containing the biofilm chip also for 30 or 60 s at concentrations of 0.25, 0.5, or 1.0 ppm. Power ultrasound and ozonation were also used in tandem for testing of their combined effect. Each of the treatments alone resulted in a significant reduction in recoverable cells, with power ultrasound being the most effective (3.8-log CFU/ml reduction after 60 s). For the ozone in combination with power ultrasound treatment, reductions were significantly (P < 0.05) higher than by either treatment alone. There were no recoverable cells after 60 s of this combined treatment when an ozone concentration of 0.5 ppm was used (7.31-log CFU/ml reduction). These results indicated that the combination of power ultrasound and ozonation may be an effective treatment for biofilm removal from stainless steel food contact surfaces.

Evaluation of the Thermo Scientific™ SureTect™ Listeria monocytogenes Assay

2014 ◽  
Vol 97 (1) ◽  
pp. 133-154 ◽  
Author(s):  
Jonathan Cloke ◽  
Carlos Leon-Velarde ◽  
Nathan Larson ◽  
Keron Dave ◽  
Katharine Evans ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Reference Method ◽  
Ice Cream ◽  
Probability Of Detection ◽  
Specific Method ◽  
Food Contact Surfaces ◽  
Significant Difference ◽  
Thermo Fisher Scientific ◽  
Reliable Performance

Abstract The Thermo Scientific™ SureTect™Listeria monocytogenes Assay is a new real-time PCR assay for the detection of Listeria monocytogenes in food and environmental samples. This assay was validated using the AOAC Research Institute (AOAC-RI) Performance Tested MethodsSM program in comparison to the reference method detailed in International Organization for Standardization 11290-1:1996, including Amendment 1:2004 with the following foods and food contact surfaces: smoked salmon, processed cheese, fresh bagged spinach, fresh cantaloupe, cooked prawns (chilled product), cooked sliced turkey meat (chilled product), ice cream, pork frankfurters, salami, ground raw beef meat (12% fat), plastic, and stainless steel. All matrixes were tested by Thermo Fisher Scientific, Microbiology Division, Basingstoke, UK. In addition, three matrixes (pork frankfurters, bagged lettuce, and stainless steel) were analyzed independently as part of the AOAC-RI controlled laboratorystudy by the University of Guelph, Canada. Using probability of detection (POD) statistical analysis, a significant difference was demonstrated between the candidate and reference methods for salami, cooked sliced turkey and ice cream in favor of the SureTect assay. For all other matrixes, no significant difference by POD was seen between the two methods during the study. Inclusivity and exclusivity testing was also conducted with 53 and30 isolates, respectively, which demonstrated that the SureTect assay was able to detect all serotypes of L. monocytogenes. None of the exclusivity isolates analyzed were detectedby the SureTect assay. Ruggedness testing was conducted to evaluate the performance of the assay with specific method deviations outside the recommended parameters open to variation, i.e., enrichment time and temperature and lysis temperature, which demonstrated that the assay gave reliable performance. Accelerated stability testing was alsoconducted, validating the assay shelf life.

Transfer of Surface-Dried Listeria monocytogenes from Stainless Steel Knife Blades to Roast Turkey Breast

2008 ◽  
Vol 71 (1) ◽  
pp. 176-181 ◽  
Author(s):  
LINDSEY A. KESKINEN ◽  
EWEN C. D. TODD ◽  
ELLIOT T. RYSER
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Biofilm Formation ◽  
Testing Machine ◽  
304 Stainless Steel ◽  
Turkey Meat ◽  
Universal Testing ◽  
Food Contact Surfaces ◽  
Ambient Storage ◽  
Total P

Listeria contamination of food contact surfaces can lead to cross-contamination of ready-to-eat foods in delicatessens. Recognizing that variations in Listeria biofilm-forming ability exist, the goal of this study was to determine whether these differences in biofilm formation would affect the Listeria transfer rate during slicing of delicatessen turkey meat. In this study, six previously identified strong and weak biofilm-forming strains of Listeria monocytogenes were grown at 22°C for 48 h on Trypticase soy agar containing 0.6% yeast extract and harvested in 0.1% peptone. Thereafter, the strains were combined to obtain two 3-strain cocktails, resuspended in turkey slurry, and inoculated onto flame-sterilized AISI grade 304 stainless steel knife blades that were subjected to 6 and 24 h of ambient storage at ~78% relative humidity. After mounting on an Instron Universal Testing Machine, these blades were used to obtain 16 slices of retail roast turkey breast. Based on an analysis of the slices by direct plating, Listeria populations decreased 3 to 5 log CFU per slice after 16 slices. Overall, total transfer to turkey was significantly greater for strong (4.4 log CFU total) as opposed to weak (3.5 log CFU total; P < 0.05) biofilm formers. In addition, significantly more cells were transferred at 6 (4.6 log CFU total) than at 24 h (3.3 log CFU total; P < 0.05) with Listeria quantifiable to the 16th slice, regardless of the inoculation level. Increased survival by the strong biofilm formers, as evidenced by viability staining, suggests that these strains are better adapted to survive stressful conditions than their weak biofilm-forming counterparts.

Quantifying the Influence of Relative Humidity, Temperature, and Diluent on the Survival and Growth of Enterobacter aerogenes

2019 ◽  
Vol 82 (12) ◽  
pp. 2135-2147 ◽  
Author(s):  
MATTHEW J. IGO ◽  
DONALD W. SCHAFFNER
Keyword(s):  
Stainless Steel ◽  
Relative Humidity ◽  
Enterobacter Aerogenes ◽  
Cell Populations ◽  
Distilled Water ◽  
Bacterial Survival ◽  
Surface Type ◽  
Food Contact Surfaces ◽  
Phosphate Buffered Saline ◽  
Peptone Broth

ABSTRACT Survival of bacteria on surfaces plays an important role in the cross-contamination of food. Temperature, relative humidity (RH), surface type, and inoculum diluent can affect bacterial survival. This study was conducted to examine how temperature, RH, and diluent affect the survival of Enterobacter aerogenes on stainless steel, polyvinyl chloride, and ceramic tile. Although surface type had little effect on survival, temperature had a clear effect. E. aerogenes survival was highest at 7°C and 15 and 50% RH on all surfaces. Some diluents allowed growth under high RH conditions. Cell populations in distilled water inoculated onto each surface decreased initially compared with populations in 1% phosphate-buffered saline (PBS) and 0.1% peptone broth. At 15 and 50% RH, cell populations in 1% PBS declined more sharply after 120 h than did those 0.1% peptone, but populations in both diluents had similar declines up to 3 weeks. Cell populations in 0.1% peptone had the greatest growth and reached the highest population density (∼8 log CFU/mL). Cell populations in PBS and distilled water increased by ∼2 log CFU/mL. When cells in 0.1% peptone were inoculated onto stainless steel at 100% RH, populations increased to ∼7 log CFU per coupon, whereas cells in 1% PBS increased to ∼5 log CFU per coupon followed by a decline over 3 weeks. DMFit and GInaFiT software modeled inactivation on surfaces at all conditions other than 100% RH at 21°C. These findings have important implications for experiments in which microorganisms are inoculated onto foods or food contact surfaces because the growth observed may be affected more by the inoculum diluent at high or uncontrolled RH than by the type of inoculated surface. HIGHLIGHTS

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