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

2004 ◽  
Vol 67 (2) ◽  
pp. 322-327 ◽  
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.

Alternative Sigma Factor σB Is Not Essential for Listeria monocytogenes Surface Attachment

2005 ◽  
Vol 68 (2) ◽  
pp. 311-317 ◽  
Author(s):  
UTE SCHWAB ◽  
YUEWEI HU ◽  
MARTIN WIEDMANN ◽  
KATHRYN J. BOOR
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Single Cells ◽  
Foodborne Pathogen ◽  
Plate Count ◽  
Initial Surface ◽  
Wild Type ◽  
Surface Attachment ◽  
Steel Analysis ◽  
Static Conditions

Listeria monocytogenes is a foodborne pathogen frequently isolated from the food processing environment. Multiple lines of evidence suggested a possible role for the L. monocytogenes alternative transcription factor sigma B (σB) in surface attachment and biofilm formation. Therefore, through plate count and microscopic techniques, the L. monocytogenes 10403S strain and an otherwise isogenic ΔsigB strain were tested for attachment to stainless steel. Analysis of microscopic images revealed that after 72 h at 24°C under static conditions the tested L. monocytogenes strains attached uniformly to surfaces as single cells. Both strains were capable of rapid attachment (i.e., numbers of attached cells were essentially the same after either 5 min or 24 h of incubation). Numbers of attached ΔsigB cells were significantly lower than those of the wild-type strain after 48 and 72 h of incubation at 24°C (P = 0.001). Similar numbers of the ΔsigB strain attached to stainless steel regardless of temperature (24 or 37°C); however, ΔsigB cells attached at higher relative numbers in the presence of 6% NaCl after 48 and 72 h. Furthermore, in the presence of Pseudomonas fluorescens, similarly high numbers of wild-type and ΔsigB cells attached to the surfaces, forming mixed biofilms. Our data suggest that σB is not required for initial surface attachment of L. monocytogenes.

scholarly journals Identification of Listeria monocytogenes Contamination in a Ready-to-Eat Meat Processing Plant in China

2021 ◽  
Vol 12 ◽  
Author(s):  
Hongzhi Zhang ◽  
Fengxia Que ◽  
Biyao Xu ◽  
Linjun Sun ◽  
Yanqi Zhu ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Biofilm Formation ◽  
Raw Materials ◽  
Case Fatality ◽  
Etiologic Agent ◽  
Health Concern ◽  
Plate Count ◽  
Processing Plant ◽  
Meat Processing ◽  
Processing Plants

Listeria monocytogenes is the etiologic agent of listeriosis, which remains a significant public health concern in many countries due to its high case-fatality rate. The constant risk of L. monocytogenes transmission to consumers remains a central challenge in the food production industry. At present, there is very little known about L. monocytogenes contamination in ready-to-eat (RTE) processing plants in China. In this study, L. monocytogenes in an RTE meat processing plant in Shanghai municipality was characterized using pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). Furthermore, the biofilm formation ability of the pathogen was also tested. Results revealed that L. monocytogenes isolates were present in 12 samples out of the 48 samples investigated. Most of them (66.7%, 8/12) were identified from the processing facilities irrespective of observed hygiene levels of aerobic plate count (APC) and coliforms. Coliforms were present in only one processing area. ST5 (1/2b) isolates were predominant (83.3%, 10/12) and were identified in two dominant pulsotypes (PTs) (three in PT3 and seven in PT4, respectively). Results of the core-genome multi-locus sequence typing (cgMLST) showed that ST5 in three PTs (PT1, PT3, and PT4) had 0–8 alleles, which confirmed that clonal transmission occurred in the RTE meat processing facilities. In addition, the biofilm formation test confirmed that the isolates from the processing facilities could form biofilms, which helped them colonize and facilitate persistence in the environment. These results indicated that common sanitation procedures regularly applied in the processing environment were efficient but not sufficient to remove L. monocytogenes isolates, especially biofilm of L. monocytogenes. Furthermore, the ST5 isolates in this study exhibited 12 alleles with one ST5 clinical isolate, which contributes to the understanding of the potential pathogenic risk that L. monocytogenes in RTE meat processing equipment posed to consumers. Therefore, strong hygienic measures, especially sanitation procedures for biofilms eradication, should be implemented to ensure the safety of raw materials. Meanwhile, continuous surveillance might be vital for the prevention and control of listeriosis caused by L. monocytogenes.

scholarly journals Resistance of Listeria monocytogenes Biofilms to Sanitizing Agents in a Simulated Food Processing Environment

2006 ◽  
Vol 72 (12) ◽  
pp. 7711-7717 ◽  
Author(s):  
Y. Pan ◽  
F. Breidt ◽  
S. Kathariou
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Food Processing ◽  
Extracellular Polymeric Substances ◽  
Control Treatment ◽  
Daily Cycles ◽  
Sterile Plastic ◽  
And Control ◽  
Ammonium Compounds ◽  
Food Processing Environment

ABSTRACT The objective of this study was to evaluate the resistance of biofilms of Listeria monocytogenes to sanitizing agents under laboratory conditions simulating a food processing environment. Biofilms were initially formed on stainless steel and Teflon coupons using a five-strain mixture of L. monocytogenes. The coupons were then subjected to repeated 24-h daily cycles. Each cycle consisted of three sequential steps: (i) a brief (60 s) exposure of the coupons to a sanitizing agent (a mixture of peroxides) or saline as a control treatment, (ii) storage of the coupons in sterile plastic tubes without any nutrients or water for 15 h, (iii) and incubation of the coupons in diluted growth medium for 8 h. This regimen was repeated daily for up to 3 weeks and was designed to represent stresses encountered by bacteria in a food processing environment. The bacteria on the coupons were reduced in number during the first week of the simulated food processing (SFP) regimen, but then adapted to the stressful conditions and increased in number. Biofilms repeatedly exposed the peroxide sanitizer in the SFP regimen developed resistance to the peroxide sanitizer as well as other sanitizers (quaternary ammonium compounds and chlorine). Interestingly, cells that were removed from the biofilms on peroxide-treated and control coupons were not significantly different in their resistance to sanitizing agents. These data suggest that the resistance of the treated biofilms to sanitizing agents may be due to attributes of extracellular polymeric substances and is not an intrinsic attribute of the cells in the biofilm.

Removal of Pseudomonas putida Biofilm and Associated Extracellular Polymeric Substances from Stainless Steel by Alkali Cleaning

2005 ◽  
Vol 68 (2) ◽  
pp. 277-281 ◽  
Author(s):  
KATERINA ANTONIOU ◽  
JOSEPH F. FRANK
Keyword(s):  
Stainless Steel ◽  
Pseudomonas Putida ◽  
Food Industry ◽  
Extracellular Polymeric Substances ◽  
Flow Conditions ◽  
Food Contact Surfaces ◽  
Biofilm Bacteria ◽  
Static Conditions ◽  
Direct Microscopic Observation ◽  
Selection Of

Alkali (NaOH)-based compounds are commonly used in the food industry to clean food contact surfaces. However, little information is available on the ability of alkali and alkali-based cleaning compounds to remove extracellular polymeric substances (EPS) produced by biofilm bacteria. The objectives of this study were to determine the temperature and NaOH concentration necessary to remove biofilm EPS from stainless steel under turbulent flow conditions (clean-in-place simulation) and to determine the ability of a commercial alkaline cleaner to remove biofilm EPS from stainless steel when applied under static conditions without heat. Biofilms were produced by growing Pseudomonas putida on stainless steel for 72 h at 25°C in a 1:10 dilution of Trypticase soy broth. The biofilms were treated using NaOH at concentrations of 1.28 to 6.0% and temperatures ranging from 66 to 70°C. Other biofilms were treated with commercial alkaline cleaner at 25 or 4°C for 1 to 30 min. Removal of EPS was determined by direct microscopic observation of samples stained with fluorescent-labeled peanut agglutinin lectin. Treatment with 1.2% NaOH at 66°C for 3 min was insufficient to remove biofilm EPS. A minimum of 2.5% NaOH at 66°C and 2.0% NaOH at 68°C for 3 min were both effective for EPS removal. Commercial alkaline cleaner removed over 99% of biofilm EPS within 1 min at 4 and 25°C under static conditions. Selection of appropriated cleaning agent formulation and use at recommended concentrations and temperatures is critical for removal of biofilm EPS from stainless steel.

A Predictive Model for Heat Inactivation of Listeria monocytogenes Biofilm on Stainless Steel

2004 ◽  
Vol 67 (12) ◽  
pp. 2712-2718 ◽  
Author(s):  
R. A. N. CHMIELEWSKI ◽  
JOSEPH F. FRANK
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Predictive Model ◽  
Enrichment Culture ◽  
Hot Water ◽  
Management Tool ◽  
Heat Inactivation ◽  
Heat Treated ◽  
Processing Plants

Heat treatment of potential biofilm-forming sites is sometimes used for control of Listeria monocytogenes in food processing plants. However, little information is available on the heat treatment required to kill L. monocytogenes present in biofilms. The purpose of this study was to develop a predictive model for the heat inactivation of L. monocytogenes in monoculture biofilms (strains Scott A and 3990) and in biofilms with competing bacteria (Pseudomonas sp. and Pantoea agglomerans) formed on stainless steel in the presence of food-derived soil. Biofilms were produced on stainless steel coupons with diluted tryptic soy broth incubated for 48 h at 25°C. Duplicate biofilm samples were heat treated for 1, 3, 5, and 15 min at 70, 72, 75, 77, and 80°C and tested for survivors using enrichment culture. The experiment was repeated six times. A predictive model was developed using logistic regression analysis of the fraction negative data. Plots showing the probability of L. monocytogenes inactivation in biofilms after heat treatment were generated from the predictive equation. The predictive model revealed that hot water sanitation of stainless steel can be effective for inactivating L. monocytogenes in a biofilm on stainless steel if time and temperature are controlled. For example, to obtain a 75% probability of total inactivation of L. monocytogenes 3990 biofilm, a heat treatment of 80°C for 11.7 min is required. The model provides processors with a risk management tool that provides predicted probabilities of L. monocytogenes inactivation and allows a choice of three heat resistance assumptions. The predictive model was validated using a five-strain cocktail of L. monocytogenes in the presence of food soil.

scholarly journals Antibiofilm Effects of Nanoparticles and Visible Light Illumination Against Listeria monocytogenes

2021 ◽  
Vol 12 ◽  
Author(s):  
Sanna Puranen ◽  
Kati Riekkinen ◽  
Jenni Korhonen
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Food Safety ◽  
Visible Light ◽  
Food Processing ◽  
Biofilm Formation ◽  
Plate Count ◽  
Light Illumination ◽  
Visible Light Illumination ◽  
Aluminum Plates

Listeria monocytogenes bacteria pose a particular risk to the food industry as the species is known to form biofilm and to survive in a wide range of challenging environmental conditions. L. monocytogenes can cause listeriosis, a serious food-borne disease, and effective and safe antibiofilm materials and sanitary methods for food processing environments are intensively sought. A variety of nanoparticle materials have been recognized as safe to use in food environments, which allows the application of nanomaterials also for food safety purposes. Nanoparticles together with light illumination generate reactive oxygen species which inactivate bacteria by breaking down cell membranes, proteins, and DNA. The main objective of this study was to evaluate the efficacy of nanomaterials and blue light illumination for L. monocytogenes ATCC 7644 biofilm inactivation. Biofilm was allowed to form for 72 h on nanocoated stainless steel and aluminum plates, after which the plates were illuminated. Non-coated control plates were used to evaluate the antibiofilm efficacy of nanocoating. Plate count method was used to evaluate bacteria counts after illumination. Nanocoating did not affect initial biofilm formation compared to the control plates. Biofilm was significantly (p < 0.05) reduced on stainless steel, aluminum, and TiO2-coated aluminum plates after 72-h illumination by 1.9, 3.2, and 5.9 log, respectively. Nanocoating with visible light illumination could be an effective and safe method for enhancing food safety in food processing facilities to control biofilm formation. Evidence of antibiofilm properties of nanomaterials together with visible light illumination is limited; hence, future studies with variable light intensities and nanomaterials are needed.

Survival of Listeria monocytogenes Attached to Stainless Steel Surfaces in the Presence or Absence of Flavobacterium spp.

2001 ◽  
Vol 64 (9) ◽  
pp. 1369-1376 ◽  
Author(s):  
PHILIP J. BREMER ◽  
IAN MONK ◽  
CAROLYN M. OSBORNE
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Mixed Culture ◽  
Cell Population ◽  
Exposure Time ◽  
Food Processing ◽  
Pure Culture ◽  
Bacterial Biofilm ◽  
Selective Agar ◽  
Steel Surfaces

Contaminated surfaces of food processing equipment are believed to be a significant source of Listeria monocytogenes to foods. However, very little is known about the survival of Listeria in processing environments. In a mixed bacterial biofilm of L. monocytogenes and Flavobacterium spp., the number of L. monocytogenes cells attaching to stainless steel increased significantly compared to when L. monocytogenes was in a pure culture. The L. monocytogenes cells in the mixed biofilms were also recoverable for significantly longer exposure periods. On colonized coupons held at 15°C and 75% humidity, decimal reduction times were 1.2 and 18.7 days for L. monocytogenes in pure and mixed biofilms, respectively. With increasing exposure time, the proportion of cells that were sublethally injured (defined as an inability to grow on selective agar) increased from 8.1% of the recoverable cell population at day 0 to 91.4% after 40 days' exposure. At 4 and −20°C, decimal reduction times for L. monocytogenes in pure culture were 2.8 and 1.4 days, respectively, and in mixed culture, 10.5 and 14.4 days, respectively. The enhanced colonization and survival of L. monocytogenes on “unclean” surfaces increase the persistence of this pathogen in food processing environments, while the increase in the percentage of sublethally injured cells in the population with time may decrease the ability of enrichment regimes to detect it.

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

2005 ◽  
Vol 68 (7) ◽  
pp. 1375-1380 ◽  
Author(s):  
BEATRICE AYEBAH ◽  
YEN-CON HUNG ◽  
JOSEPH F. FRANK
Keyword(s):  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Combined Treatment ◽  
Bactericidal Effect ◽  
Control Treatment ◽  
Bacterial Populations ◽  
Combined Use ◽  
Processing Plants ◽  
Steel Surfaces ◽  
Type 304

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.

Biodegradation of chlorophenols by immobilized pure-culture microorganisms

1996 ◽  
Vol 34 (10) ◽  
pp. 67-72 ◽  
Author(s):  
Lu Chih-Jen ◽  
Lee Chi-Mei ◽  
Huang Chiou-Zong
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Pseudomonas Putida ◽  
Pure Culture ◽  
The Other ◽  
Batch Reactors ◽  
Agrobacterium Radiobacter ◽  
Culture Cells ◽  
Lag Period

The biodegradation of phenol and chlorophenols by immobilized pure-culture cells was conducted by a series of batch reactors. The microorganisms used in this study were Pseudomonas putida, Psuedomonas testosteroni, Pseudomonas aeruginosa, and Agrobacterium radiobacter. All four species showed the ortho-cleavage pathway to metabolize chlorophenols. Among the four species, P. testosteroni, P. putida, and P. aeruginosa could effectively remove phenol at 200 mg/l. P. testosteroni could effectively remove 2-chlorophenol at 10mg/l. However, the other three species, P. putida, P. aeruginosa, and A. radiobacter, could not effectively remove 2-chlorophenol. Although 3-chlorophenol is a recalcitrant compound, P. testosteroni also could rapidly metabolize 3-chlorophenol at 10 mg/l. The removal of 4-chlorophenol at 10 mg/l by P. testosteroni reached 98% within one day. P. aeruginosa and A. radiobacter also could metabolize 4-chlorophenol after 2 and 7 days of lag period, respectively.

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.

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