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Chaves RD, Kumazawa SH, Khaneghah AM, Alvarenga VO, Hungaro HM, Sant'Ana AS. Comparing the susceptibility to sanitizers, biofilm-forming ability, and biofilm resistance to quaternary ammonium and chlorine dioxide of 43 Salmonella enterica and Listeria monocytogenes strains. Food Microbiol 2024; 117:104380. [PMID: 37918997 DOI: 10.1016/j.fm.2023.104380] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 08/28/2023] [Accepted: 09/05/2023] [Indexed: 11/04/2023]
Abstract
This study determined the susceptibility to sanitizers and biofilm-forming ability on stainless steel of 43 Salmonella enterica and Listeria monocytogenes strains. Besides, the biofilm resistance to sanitizers of four bacterial pathogen strains was evaluated. Four sanitizers commonly used in the food industry were tested: peracetic acid (PAA), chlorine dioxide (ClO2), sodium hypochlorite (SH), and quaternary ammonium compound (QAC). The susceptibility to sanitizers varied widely among the strains of both pathogens. On the other hand, the number of biofilm-associated cells on the stainless-steel surface was >5 log CFU/cm2 for all of them. Only one Salmonella strain and two L. monocytogenes strains stood out as the least biofilm-forming. The resistance of biofilms to sanitizers also varied among strains of each pathogen. Biofilms of L. monocytogenes were more susceptible to the disinfection process with ClO2 and QAC than those of Salmonella. However, no correlation was observed between the ability to form denser biofilm and increased sanitizer resistance. In general, chlorine compounds were more effective than other sanitizers in inactivating planktonic cells and biofilms.
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Affiliation(s)
- Rafael D Chaves
- Department of Food Science and Nutrition, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil
| | - Samuel H Kumazawa
- Department of Food Science and Nutrition, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil
| | - Amin Mousavi Khaneghah
- Department of Food Science and Nutrition, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil
| | - Verônica O Alvarenga
- Department of Food Science and Nutrition, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil; Department of Food, Faculty of Pharmacy, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Humberto M Hungaro
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil
| | - Anderson S Sant'Ana
- Department of Food Science and Nutrition, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil.
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Finn L, Onyeaka H, O’Neill S. Listeria monocytogenes Biofilms in Food-Associated Environments: A Persistent Enigma. Foods 2023; 12:3339. [PMID: 37761048 PMCID: PMC10529182 DOI: 10.3390/foods12183339] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/31/2023] [Accepted: 09/01/2023] [Indexed: 09/29/2023] Open
Abstract
Listeria monocytogenes (LM) is a bacterial pathogen responsible for listeriosis, a foodborne illness associated with high rates of mortality (20-30%) and hospitalisation. It is particularly dangerous among vulnerable groups, such as newborns, pregnant women and the elderly. The persistence of this organism in food-associated environments for months to years has been linked to several devastating listeriosis outbreaks. It may also result in significant costs to food businesses and economies. Currently, the mechanisms that facilitate LM persistence are poorly understood. Unravelling the enigma of what drives listerial persistence will be critical for developing more targeted control and prevention strategies. One prevailing hypothesis is that persistent strains exhibit stronger biofilm production on abiotic surfaces in food-associated environments. This review aims to (i) provide a comprehensive overview of the research on the relationship between listerial persistence and biofilm formation from phenotypic and whole-genome sequencing (WGS) studies; (ii) to highlight the ongoing challenges in determining the role biofilm development plays in persistence, if any; and (iii) to propose future research directions for overcoming these challenges.
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Affiliation(s)
| | - Helen Onyeaka
- School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, UK
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Abou Elez RMM, Elsohaby I, Al-Mohammadi AR, Seliem M, Tahoun ABMB, Abousaty AI, Algendy RM, Mohamed EAA, El-Gazzar N. Antibacterial and anti-biofilm activities of probiotic Lactobacillus plantarum against Listeria monocytogenes isolated from milk, chicken and pregnant women. Front Microbiol 2023; 14:1201201. [PMID: 37538844 PMCID: PMC10394229 DOI: 10.3389/fmicb.2023.1201201] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 07/07/2023] [Indexed: 08/05/2023] Open
Abstract
Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen that poses significant risks to public health and food safety. The present study aimed to identify the presence of Listeria spp. in various samples, including pasteurized milk, chicken fillets, and stool samples from pregnant women in Sharkia Governorate, Egypt. Additionally, the study identified the serotypes, virulence-associated genes, antimicrobial resistance patterns, and biofilm formation in L. monocytogenes isolates. Moreover, the antibacterial and anti-biofilm activity of Lactobacillus plantarum ATCC 14917 (L. plantarum) against L. monocytogenes isolates was investigated. A cross-sectional study was conducted from August 2021 to January 2022 to collect 300 samples of pasteurized milk, chicken fillets, and stool from pregnant women admitted to outpatient clinics of hospitals. The results showed that 32.7% of the samples were positive for Listeria spp., including L. innocua (48.9%), L. monocytogenes (26.5%), L. ivanovii (14.3%), L. grayi (5.1%), and L. welshimeri (5.1%). Among all L. monocytogenes isolates, hlyA, actA, inlC, and inlJ virulence-associated genes were detected. However, the virulence genes plcB, iap, and inlA were found in 10 (38.5%), 8 (30.8%), and 25 (96.2%) isolates, respectively. The L. monocytogenes isolates classified into four serotypes (1/2a, 1/2b, 1/2c, and 4b), with 1/2a and 4b each identified in 30.8% of the isolates, while 1/2b and 1/2c were identified in 19.2% of the isolates. All L. monocytogenes isolates showed 100% resistance to streptomycin, kanamycin, and nalidix acid, and 92.3% of isolates showed gentamicin resistance. However, all isolates were susceptible to ampicillin and ampicillin/sulbactam. Multidrug resistance (MDR) was observed in 20 (76.9%) L. monocytogenes isolates. The biofilm formation ability of 26 L. monocytogenes isolates was evaluated at different incubation temperatures. At 4°C, 25°C, and 37°C, 53.8, 69.2, and 80.8% of the isolates, respectively, were biofilm producers. Furthermore, 23.1% were strong biofilm producers at both 4°C and 25°C, while 34.6% were strong biofilm formers at 37°C. Treating L. monocytogenes isolates with L. plantarum cell-free supernatant (CFS) reduced the number of biofilm-producing isolates to 15.4, 42.3, and 53.8% at 4°C, 25°C, and 37°C, respectively. L. plantarum's CFS antibacterial activity was tested against six virulent, MDR, and biofilm-forming L. monocytogenes isolates. At a concentration of 5 μg/mL of L. plantarum CFS, none of the L. monocytogenes isolates exhibited an inhibition zone. However, an inhibition zone was observed against L. monocytogenes strains isolated from pasteurized milk and pregnant women's stools when using a concentration of 10 μg/mL. Transmission electron microscopy (TEM) revealed that L. plantarum CFS induced morphological and intracellular structural changes in L. monocytogenes. In conclusion, this study identified virulent MDR L. monocytogenes isolates with strong biofilm-forming abilities in food products in Egypt, posing significant risks to food safety. Monitoring the prevalence and antimicrobial resistance profile of L. monocytogenes in dairy and meat products is crucial to enhance their safety. Although L. plantarum CFS showed potential antibacterial and anti-biofilm effects against L. monocytogenes isolates, further research is needed to explore its full probiotic potential.
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Affiliation(s)
- Rasha M. M. Abou Elez
- Department of Zoonoses, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | - Ibrahim Elsohaby
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR, China
- Centre for Applied One Health Research and Policy Advice (OHRP), City University of Hong Kong, Kowloon, Hong Kong SAR, China
- Department of Animal Medicine, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | | | - Marwa Seliem
- Department of Zoonoses, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | - Asmaa B. M. B. Tahoun
- Department of Food Hygiene, Safety and Technology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | - Amira I. Abousaty
- Department of Botany and Microbiology, Faculty of Science, Zagazig University, Zagazig, Egypt
| | - Reem M. Algendy
- Department of Food Hygiene, Safety and Technology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | - Eman A. A. Mohamed
- Department of Microbiology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt
| | - Nashwa El-Gazzar
- Department of Botany and Microbiology, Faculty of Science, Zagazig University, Zagazig, Egypt
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Sugar Modification of Wall Teichoic Acids Determines Serotype-Dependent Strong Biofilm Production in Listeria monocytogenes. Microbiol Spectr 2022; 10:e0276922. [PMID: 36190419 PMCID: PMC9603678 DOI: 10.1128/spectrum.02769-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Biofilm production is responsible for persistent food contamination by Listeria monocytogenes, threatening food safety and public health. Human infection and food contamination with L. monocytogenes are caused primarily by serotypes 1/2a, 1/2b, and 4b. However, the association of biofilm production with phylogenic lineage and serotype has not yet been fully understood. In this study, we measured the levels of biofilm production in 98 clinical strains of L. monocytogenes at 37°C, 25°C, and 4°C. The phylogenetic clusters grouped by core genome multilocus sequence typing (cgMLST) exhibited association between biofilm production and phylogenetic lineage and serotype. Whereas clusters 1 and 3 consisting of serotype 4b strains exhibited weak biofilm production, clusters 2 (serotype 1/2b) and 4 (serotype 1/2a) were composed of strong biofilm formers. Particularly, cluster 2 (serotype 1/2b) strains exhibited the highest levels of biofilm production at 37°C, and the levels of biofilm production of cluster 4 (serotype 1/2a) strains were significantly elevated at all tested temperatures. Pan-genome analysis identified 22 genes unique to strong biofilm producers, most of which are related to the synthesis and modification of teichoic acids. Notably, a knockout mutation of the rml genes related to the modification of wall teichoic acids with l-rhamnose, which is specific to serogroup 1/2, significantly reduced the level of biofilm production by preventing biofilm maturation. Here, the results of our study show that biofilm production in L. monocytogenes is related to phylogeny and serotype and that the modification of wall teichoic acids with l-rhamnose is responsible for serotype-specific strong biofilm formation in L. monocytogenes. IMPORTANCE Biofilm formation on the surface of foods or food-processing facilities by L. monocytogenes is a serious food safety concern. Here, our data demonstrate that the level of biofilm production differs among serotypes 1/2a, 1/2b, and 4b depending on the temperature. Furthermore, sugar decoration of bacterial cell walls with l-rhamnose is responsible for strong biofilm production in serotypes 1/2a and 1/2b, commonly isolated from foods and listeriosis cases. The findings in this study improve our understanding of the association of biofilm production with phylogenetic lineage and serotype in L. monocytogenes.
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Persistence of Listeria monocytogenes ST5 in Ready-to-Eat Food Processing Environment. Foods 2022; 11:foods11172561. [PMID: 36076746 PMCID: PMC9454991 DOI: 10.3390/foods11172561] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/05/2022] [Accepted: 08/19/2022] [Indexed: 11/17/2022] Open
Abstract
Most human listeriosis is foodborne, and ready-to-eat (RET) foods contaminated by Listeria monocytogenes during processing are found to be common vehicles. In this study, a total of four L. monocytogens STs (ST5, ST121, ST120, and ST2) have been identified in two RTE food plants from 2019 to 2020 in Shanghai, China. The L. monocytogenes ST5 was predominant in one RTE food processing plant, and it persists in the RTE meat processing plant with continued clone transmission. The genetic features of the four STs isolates were different. ST5 and ST121 had the three genes clpL, mdrL, and lde; however, ST120 and ST2 had two genes except for clpL. SSI-1was present in ST5, ST121, and ST120. Additionally, SSI-2 was present only in the ST121 isolates. ST120 had all six biofilm-forming associated genes (actA, prfA, lmo0673, recO, lmo2504 and luxS). The ST2 isolate had only three biofilm-forming associated genes, which were prfA, lmo0673, and recO. The four ST isolates had different biofilm formation abilities at different stages. The biofilm formation ability of ST120 was significantly higher when grown for one day. However, the biofilm formation ability of ST120 reduced significantly after growing for four days. In contrast, the biofilm formation ability of ST5 and ST121 increased significantly. These results suggested that ST5 and ST121 had stronger ability to adapt to stressful environments. Biofilms formed by all four STs grown over four days can be sanitized entirely by a disinfectant concentration of 500 mg/L. Additionally, only ST5 and ST121 biofilm cells survived in sub-lethal concentrations of chlorine-containing disinfectant. These results suggested that ST5 and ST121 were more resistant to chlorine-containing disinfectants. These results indicated that the biofilm formation ability of L. monocytogenes isolates changed at different stages. Additionally, the persistence in food processing environments might be verified by the biofilm formation, stress resistance, etc. Alternatively, these results underlined that disinfectants should be used at lethal concentrations. More attention should be paid to ST5 and ST121, and stronger surveillance should be taken to prevent and control the clonal spread of L. monocytogenes isolates in food processing plants in Shanghai.
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Wang Y, Sun L, Hu L, Wang Z, Wang X, Dong Q. Adhesion and kinetics of biofilm formation and related gene expression of Listeria monocytogenes in response to nutritional stress. Food Res Int 2022; 156:111143. [DOI: 10.1016/j.foodres.2022.111143] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/11/2022] [Accepted: 03/13/2022] [Indexed: 01/08/2023]
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Harrison K, Curtin C. Microbial Composition of SCOBY Starter Cultures Used by Commercial Kombucha Brewers in North America. Microorganisms 2021; 9:1060. [PMID: 34068887 PMCID: PMC8156240 DOI: 10.3390/microorganisms9051060] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/04/2021] [Accepted: 05/05/2021] [Indexed: 12/25/2022] Open
Abstract
Kombucha fermentation is initiated by transferring a solid-phase cellulosic pellicle into sweetened tea and allowing the microbes that it contains to initiate the fermentation. This pellicle, commonly referred to as a symbiotic culture of bacteria and yeast (SCOBY), floats to the surface of the fermenting tea and represents an interphase environment, where embedded microbes gain access to oxygen as well as nutrients in the tea. To date, various yeast and bacteria have been reported to exist within the SCOBY, with little consensus as to which species are essential and which are incidental to Kombucha production. In this study, we used high-throughput sequencing approaches to evaluate spatial homogeneity within a single commercial SCOBY and taxonomic diversity across a large number (n = 103) of SCOBY used by Kombucha brewers, predominantly in North America. Our results show that the most prevalent and abundant SCOBY taxa were the yeast genus Brettanomyces and the bacterial genus Komagataeibacter, through careful sampling of upper and lower SCOBY layers. This sampling procedure is critical to avoid over-representation of lactic acid bacteria. K-means clustering was used on metabarcoding data of all 103 SCOBY, delineating four SCOBY archetypes based upon differences in their microbial community structures. Fungal genera Zygosaccharomyces, Lachancea and Starmerella were identified as the major compensatory taxa for SCOBY with lower relative abundance of Brettanomyces. Interestingly, while Lactobacillacae was the major compensatory taxa where Komagataeibacter abundance was lower, phylogenic heat-tree analysis infers a possible antagonistic relationship between Starmerella and the acetic acid bacterium. Our results provide the basis for further investigation of how SCOBY archetype affects Kombucha fermentation, and fundamental studies of microbial community assembly in an interphase environment.
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Affiliation(s)
- Keisha Harrison
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97330, USA;
| | - Chris Curtin
- Department of Food Science and Technology, Oregon State University, Corvallis, OR 97330, USA;
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97330, USA
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Kostoglou D, Tsaklidou P, Iliadis I, Garoufallidou N, Skarmoutsou G, Koulouris I, Giaouris E. Advanced Killing Potential of Thymol against a Time and Temperature Optimized Attached Listeria monocytogenes Population in Lettuce Broth. Biomolecules 2021; 11:397. [PMID: 33800308 PMCID: PMC7998208 DOI: 10.3390/biom11030397] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/10/2021] [Accepted: 03/04/2021] [Indexed: 12/27/2022] Open
Abstract
Fresh vegetables and salads are increasingly implicated in outbreaks of foodborne infections, such as those caused by Listeria monocytogenes, a dangerous pathogen that can attach to the surfaces of the equipment creating robust biofilms withstanding the killing action of disinfectants. In this study, the antimicrobial efficiency of a natural plant terpenoid (thymol) was evaluated against a sessile population of a multi-strain L. monocytogenes cocktail developed on stainless steel surfaces incubated in lettuce broth, under optimized time and temperature conditions (54 h at 30.6 °C) as those were determined following response surface modeling, and in comparison, to that of an industrial disinfectant (benzalkonium chloride). Prior to disinfection, the minimum bactericidal concentrations (MBCs) of each compound were determined against the planktonic cells of each strain. The results revealed the advanced killing potential of thymol, with a concentration of 625 ppm (= 4 × MBC) leading to almost undetectable viable bacteria (more than 4 logs reduction following a 15-min exposure). For the same degree of killing, benzalkonium chloride needed to be used at a concentration of at least 20 times more than its MBC (70 ppm). Discriminative repetitive sequence-based polymerase chain reaction (rep-PCR) also highlighted the strain variability in both biofilm formation and resistance. In sum, thymol was found to present an effective anti-listeria action under environmental conditions mimicking those encountered in the salad industry and deserves to be further explored to improve the safety of fresh produce.
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Affiliation(s)
| | | | | | | | | | | | - Efstathios Giaouris
- Laboratory of Food Microbiology and Hygiene, Department of Food Science and Nutrition, School of the Environment, University of the Aegean, 81400 Myrina, Lemnos, Greece; (D.K.); (P.T.); (I.I.); (N.G.); (G.S.); (I.K.)
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Hu J, Tang Y, Ai F, Lin M, Ruan J. Biofilm for leaching precious metals from waste printed circuit boards using biocyanidation technology. JOURNAL OF HAZARDOUS MATERIALS 2021; 403:123586. [PMID: 32795820 DOI: 10.1016/j.jhazmat.2020.123586] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 07/23/2020] [Accepted: 07/25/2020] [Indexed: 06/11/2023]
Abstract
Presently, biocyanidation technology is being usually adopted to recover precious metals from an increasing quantity of waste printed circuit boards. The main aim of this work was to investigate the biofilm formation of Pseudomonas and its ability to leach precious metals. Based on batch experiments, strain 113 showed the highest biofilm-forming activity in optimal culture conditions of pH 7.0, 25 °C, and 1/25 NB medium among the Pseudomonas strains isolated. Both low concentrations of Cu2+ (500 ppm) and Ag+ (2.5 ppm) promoted biofilm formation. Under the optimal culture conditions for biofilm formation, the concentration of CN- was up to 5.0 ppm. In the continuous silver leaching experiment, the Ag+ concentration reached 4.0 ppm and the leaching efficiency was 14.7 % at 7 d. The results of this study may contribute to the construction of a bioreactor used for continuous leaching of waste printed circuit boards in an attempt to recover precious metals. Our results may also aid in the industrialization of biocyanidation technology.
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Affiliation(s)
- Jian Hu
- School of Environmental Science and Engineering, Yangzhou University, 196 Huayang Xi Road, Yangzhou, People's Republic of China.
| | - Yun Tang
- School of Environmental Science and Engineering, Yangzhou University, 196 Huayang Xi Road, Yangzhou, People's Republic of China
| | - Fangqiu Ai
- School of Environmental Science and Engineering, Yangzhou University, 196 Huayang Xi Road, Yangzhou, People's Republic of China
| | - Mi Lin
- School of Environmental Science and Engineering, Sun Yat-Sen University, 135 Xingang Xi Road, Guangzhou, 510275, People's Republic of China
| | - Jujun Ruan
- School of Environmental Science and Engineering, Sun Yat-Sen University, 135 Xingang Xi Road, Guangzhou, 510275, People's Republic of China.
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The ability of Listeria monocytogenes to form biofilm on surfaces relevant to the mushroom production environment. Int J Food Microbiol 2020; 317:108385. [DOI: 10.1016/j.ijfoodmicro.2019.108385] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 09/08/2019] [Accepted: 10/08/2019] [Indexed: 01/08/2023]
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Rodríguez-Campos D, Rodríguez-Melcón C, Alonso-Calleja C, Capita R. Persistent Listeria monocytogenes Isolates from a Poultry-Processing Facility Form more Biofilm but Do Not Have a Greater Resistance to Disinfectants Than Sporadic Strains. Pathogens 2019; 8:E250. [PMID: 31756896 PMCID: PMC6963312 DOI: 10.3390/pathogens8040250] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 10/19/2019] [Accepted: 10/27/2019] [Indexed: 12/26/2022] Open
Abstract
Some strains of Listeria monocytogenes can persist in food-processing environments, increasing the likelihood of the contamination of foodstuffs. To identify traits that contribute to bacterial persistence, a selection of persistent and sporadic L. monocytogenes isolates from a poultry-processing facility was investigated for biofilm-forming ability (crystal violet assay). The susceptibility of sessile cells to treatments (five minutes) with sodium hypochlorite having 10% active chlorine (SHY: 10,000 ppm, 25,000 ppm, and 50,000 ppm) and benzalkonium chloride (BZK: 2500 ppm, 10,000 ppm, and 25,000 ppm) was also studied. All isolates exhibited biofilm formation on polystyrene. Persistent strains showed larger (p < 0.001) biofilm formation (OD580 = 0.301 ± 0.097) than sporadic strains (OD580 = 0.188 ± 0.082). A greater susceptibility to disinfectants was observed for biofilms of persistent strains than for those of sporadic strains. The application of SHY reduced biofilms only for persistent strains. BZK increased OD580 in persistent strains (2500 ppm) and in sporadic strains (all concentrations). These results indicate that the use of BZK at the concentrations tested could represent a public health risk. Findings in this work suggest a link between persistence and biofilm formation, but do not support a relationship between persistence and the resistance of sessile cells to disinfectants.
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Affiliation(s)
- Daniel Rodríguez-Campos
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, E-24071 León, Spain; (D.R.-C.); (C.R.-M.); (C.A.-C.)
- Institute of Food Science and Technology, University of León, E-24071 León, Spain
| | - Cristina Rodríguez-Melcón
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, E-24071 León, Spain; (D.R.-C.); (C.R.-M.); (C.A.-C.)
- Institute of Food Science and Technology, University of León, E-24071 León, Spain
| | - Carlos Alonso-Calleja
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, E-24071 León, Spain; (D.R.-C.); (C.R.-M.); (C.A.-C.)
- Institute of Food Science and Technology, University of León, E-24071 León, Spain
| | - Rosa Capita
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, E-24071 León, Spain; (D.R.-C.); (C.R.-M.); (C.A.-C.)
- Institute of Food Science and Technology, University of León, E-24071 León, Spain
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Alonso-Calleja C, Gómez-Fernández S, Carballo J, Capita R. Prevalence, Molecular Typing, and Determination of the Biofilm-Forming Ability of Listeria monocytogenes Serotypes from Poultry Meat and Poultry Preparations in Spain. Microorganisms 2019; 7:E529. [PMID: 31694193 PMCID: PMC6920909 DOI: 10.3390/microorganisms7110529] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/11/2019] [Accepted: 10/23/2019] [Indexed: 11/17/2022] Open
Abstract
A study was undertaken of the presence of Listeria monocytogenes in 260 samples of poultry meat obtained from retail outlets in northwestern Spain. L. monocytogenes was detected in 20 samples (7.7%). Twenty strains (one strain per positive sample) were characterized. The strains belonged to 10 serotypes: 1/2a (2 strains), 1/2b (2), 1/2c (2), 3a (1), 3b (2), 3c (2), 4a (2), 4b (4), 4c (1), and 4d (2). Cluster analysis (ribotyping; EcoRI) showed a strong genetic relationship between strains isolated from samples coming from different outlets. Ribotyping permitted some isolates of the same serotype to be differentiated, which points to the possible usefulness of this technique in the epidemiological surveillance of L. monocytogenes. All strains formed biofilm on polystyrene, as shown by confocal laser scanning microscopy. The biovolume (between 621.7 ± 36.0 µm3 and 62,984.0 ± 14,888.2 µm3 in the observational field of 14,161 μm2), percentage of surface coverage (from 2.17 ± 0.84% to 94.43 ± 3.97%), roughness (between 0.399 ± 0.052 and 0.830 ± 0.022), and maximum thickness (between 9.00 ± 0.00 µm and 24.00 ± 14.93 µm) of biofilms varied between strains (p < 0.05). These results expand knowledge of the characteristics of L. monocytogenes isolates from poultry.
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Affiliation(s)
- Carlos Alonso-Calleja
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, E-24071 León, Spain; (C.A.-C.); (S.G.-F.)
- Institute of Food Science and Technology, University of León, E-24071 León, Spain
| | - Sara Gómez-Fernández
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, E-24071 León, Spain; (C.A.-C.); (S.G.-F.)
- Institute of Food Science and Technology, University of León, E-24071 León, Spain
| | - Javier Carballo
- Area of Food Technology, University of Vigo, E-32004 Ourense, Spain;
| | - Rosa Capita
- Department of Food Hygiene and Technology, Veterinary Faculty, University of León, E-24071 León, Spain; (C.A.-C.); (S.G.-F.)
- Institute of Food Science and Technology, University of León, E-24071 León, Spain
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13
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Skowron K, Wałecka-Zacharska E, Grudlewska K, Gajewski P, Wiktorczyk N, Wietlicka-Piszcz M, Dudek A, Skowron KJ, Gospodarek-Komkowska E. Disinfectant Susceptibility of Biofilm Formed by Listeria monocytogenes under Selected Environmental Conditions. Microorganisms 2019; 7:E280. [PMID: 31438656 PMCID: PMC6780692 DOI: 10.3390/microorganisms7090280] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 08/16/2019] [Accepted: 08/19/2019] [Indexed: 12/20/2022] Open
Abstract
Listeria monocytogenes is a one of the most important food-borne pathogens. Its ability to form biofilm contributes to increased resistance to disinfectants and inefficient disinfection, posing a serious threat for the food industry, and in the end the consumer. The aim of this study was the comparison of the biofilm formation ability of L. monocytogenes strains on stainless steel, under different environmental conditions (temperature, pH, NaCl concentration, nutrients availability), and the assessment of biofilm susceptibility to disinfectants. The bactericidal activity of four disinfectants in two concentrations (100% and 50% of working solution) against biofilm was conducted on four clinical strains, four strains isolated from food and one reference strain ATCC 19111. It was found that biofilm susceptibility to disinfectants was influenced by environmental conditions. Biofilm susceptibility correlated with the decrease of temperature, pH, nutrients availability and salinity of the environment. The least sensitive to disinfectants was biofilm produced at pH = 4 (the bacterial number ranged from 0.25 log CFU × cm-2 to 1.72 log CFU × cm-2) whereas the most sensitive was biofilm produced at pH = 9 (5.16 log CFU × cm-2 to 7.84 log CFU × cm-2). Quatosept was the most effective disinfectant, regardless of the conditions. In conclusion, biofilm susceptibility to disinfectants is strain-dependent and is affected by environmental conditions.
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Affiliation(s)
- Krzysztof Skowron
- Department of Microbiology, Nicolaus Copernicus University in Toruń, L. Rydygier Collegium Medicum in Bydgoszcz, 9 M. Skłodowska-Curie St., 85-094 Bydgoszcz, Poland.
| | - Ewa Wałecka-Zacharska
- Department of Food Hygiene and Consumer Health, Wrocław University of Environmental and Life Sciences, 31 C.K. Norwida St., 50-375 Wrocław, Poland
| | - Katarzyna Grudlewska
- Department of Microbiology, Nicolaus Copernicus University in Toruń, L. Rydygier Collegium Medicum in Bydgoszcz, 9 M. Skłodowska-Curie St., 85-094 Bydgoszcz, Poland
| | - Piotr Gajewski
- Department of Microbiology, Nicolaus Copernicus University in Toruń, L. Rydygier Collegium Medicum in Bydgoszcz, 9 M. Skłodowska-Curie St., 85-094 Bydgoszcz, Poland
| | - Natalia Wiktorczyk
- Department of Microbiology, Nicolaus Copernicus University in Toruń, L. Rydygier Collegium Medicum in Bydgoszcz, 9 M. Skłodowska-Curie St., 85-094 Bydgoszcz, Poland
| | - Magdalena Wietlicka-Piszcz
- Department of Theoretical Foundations of Biomedical Sciences and Medical Computer Science, Nicolaus Copernicus University in Toruń, L. Rydygier Collegium Medicum in Bydgoszcz, 9 M. Skłodowska-Curie St., 85-094 Bydgoszcz, Poland
| | - Andżelika Dudek
- Department of Microbiology, Nicolaus Copernicus University in Toruń, L. Rydygier Collegium Medicum in Bydgoszcz, 9 M. Skłodowska-Curie St., 85-094 Bydgoszcz, Poland
| | - Karolina Jadwiga Skowron
- Faculty of Telecommunication, Information Technology and Electrical Engineering, Institute of Telecommunications and Computer Science, UTP University of Science and Technology, Al. prof. S. Kaliskiego 7, 85-796 Bydgoszcz, Poland
| | - Eugenia Gospodarek-Komkowska
- Department of Microbiology, Nicolaus Copernicus University in Toruń, L. Rydygier Collegium Medicum in Bydgoszcz, 9 M. Skłodowska-Curie St., 85-094 Bydgoszcz, Poland
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14
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Agustín MDR, Brugnoni L. Multispecies biofilms betweenListeria monocytogenesandListeria innocuawith resident microbiota isolated from apple juice processing equipment. J Food Saf 2018. [DOI: 10.1111/jfs.12499] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- María del Rosario Agustín
- Department of Biology, Biochemistry and Pharmacy; Universidad Nacional del Sur (UNS); Bahía Blanca Argentina
| | - Lorena Brugnoni
- Institute of Biological and Biomedical Sciences of the South (INBIOSUR); Universidad Nacional del Sur (UNS), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Bahía Blanca Argentina
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15
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Karley D, Shukla SK, Rao TS. Isolation and characterization of culturable bacteria present in the spent nuclear fuel pool water. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:20518-20526. [PMID: 29063404 DOI: 10.1007/s11356-017-0376-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Accepted: 09/28/2017] [Indexed: 06/07/2023]
Abstract
A spent nuclear fuel (SNF) pool is a key facility for safe management of nuclear waste, where spent nuclear fuel rods are stored in a water pool. The spent fuel rods carry a significant amount of radioactivity; they are either recycled or stored for further processing. Pool water acts as a heat sink as well as a shield against the radiation present in spent/burned fuel rods. The water used in these pools is filtered by an ultra-filtration process which makes certain the purity of water. As the life span of these pools is approximately 20 to 40 years, the maintenance of pure water is a big challenge. A number of researchers have shown the presence of bacterial communities in this ultrapure water. The bacterial types present in SNF pool water is of increasing interest for their potential bioremediation applications for radioactive waste. The present study showed the isolation of six bacterial species in the SNF pool water samples, which had significant radio-tolerance (D10 value 248 Gy to 2 kGy) and also biofilm-forming capabilities. These strains were also investigated for their heavy metal removal capacity. Maximum biofilm-mediated heavy metal (Co and Ni) removal (up to 3.8 μg/mg of biomass) was observed by three isolates (FPB1, FPB4, and FPB6). The ability of these bacterial isolates to survive in radioactive environments can be of great interest for remediation of radioactive contaminants.
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Affiliation(s)
- Dugeshwar Karley
- Biofouling and Thermal Ecology Section, Water & Steam Chemistry Division, Bhabha Atomic Research Centre Facilities, Kalpakkam, 603102, India
| | - Sudhir K Shukla
- Biofouling and Thermal Ecology Section, Water & Steam Chemistry Division, Bhabha Atomic Research Centre Facilities, Kalpakkam, 603102, India
- Homi Bhabha National Institute, Mumbai, 400094, India
| | - Toleti Subba Rao
- Biofouling and Thermal Ecology Section, Water & Steam Chemistry Division, Bhabha Atomic Research Centre Facilities, Kalpakkam, 603102, India.
- Homi Bhabha National Institute, Mumbai, 400094, India.
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16
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Nagar V, Pansare Godambe L, Bandekar JR, Shashidhar R. Biofilm formation by Aeromonas
strains under food-related environmental stress conditions. J FOOD PROCESS PRES 2017. [DOI: 10.1111/jfpp.13182] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Vandan Nagar
- Food Technology Division; Bhabha Atomic Research Centre; Mumbai 400 085 India
| | | | - Jayant R. Bandekar
- Food Technology Division; Bhabha Atomic Research Centre; Mumbai 400 085 India
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17
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Hayat S, Sabri AN, McHugh TD. Chloroform extract of turmeric inhibits biofilm formation, EPS production and motility in antibiotic resistant bacteria. J GEN APPL MICROBIOL 2017; 63:325-338. [DOI: 10.2323/jgam.2017.01.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Sumreen Hayat
- Department of Microbiology and Molecular Genetics, University of the Punjab, Quaid-e-Azam Campus
- Department of Microbiology, Government College University
| | - Anjum N. Sabri
- Department of Microbiology and Molecular Genetics, University of the Punjab, Quaid-e-Azam Campus
| | - Timothy D. McHugh
- Center for Clinical Microbiology, Royal Free Campus, University College London
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18
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Overney A, Chassaing D, Carpentier B, Guillier L, Firmesse O. Development of synthetic media mimicking food soils to study the behaviour of Listeria monocytogenes on stainless steel surfaces. Int J Food Microbiol 2016; 238:7-14. [PMID: 27589019 DOI: 10.1016/j.ijfoodmicro.2016.08.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 08/16/2016] [Accepted: 08/24/2016] [Indexed: 12/21/2022]
Abstract
Listeria monocytogenes is one of the main targets of hygiene procedures in the ready-to-eat food industry due to its ability to persist for months or even years in processing plants, where it can contaminate food during processing. The factors associated with persistence are often those that foster growth, which itself depends on food contamination of surfaces. It is therefore essential to experiment by using food soils or media modelling these soils to understand the behaviour of L. monocytogenes on surfaces of food processing plants. Thus, we set up an experimental plan including three physiological parameters characteristic of the behaviour of cells on surfaces, namely spatial distribution, adhesion forces and the physiological state of sessile L. monocytogenes. These were recorded in two food soils: smoked salmon juice and meat exudate. According to our results, the behaviour of L. monocytogenes on stainless steel surfaces is highly dependent on the food soil used. The presence of viable but non-culturable (VBNC) cells was demonstrated using meat exudate, while all viable cells were recovered using smoked salmon juice. Moreover, on the basis of our criteria and after validation with three strains of L. monocytogenes, we showed that smoked salmon juice can be substituted by a modified culture medium, demonstrating that drawbacks associated with the use of food soils can be overcome.
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Affiliation(s)
- Anaïs Overney
- Université Paris-Est, ANSES, Laboratory for Food Safety, 94701 Maisons-Alfort, France
| | - Danielle Chassaing
- Université Paris-Est, ANSES, Laboratory for Food Safety, 94701 Maisons-Alfort, France
| | - Brigitte Carpentier
- Université Paris-Est, ANSES, Laboratory for Food Safety, 94701 Maisons-Alfort, France
| | - Laurent Guillier
- Université Paris-Est, ANSES, Laboratory for Food Safety, 94701 Maisons-Alfort, France
| | - Olivier Firmesse
- Université Paris-Est, ANSES, Laboratory for Food Safety, 94701 Maisons-Alfort, France.
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19
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Kyoui D, Hirokawa E, Takahashi H, Kuda T, Kimura B. Effect of glucose on Listeria monocytogenes biofilm formation, and assessment of the biofilm's sanitation tolerance. BIOFOULING 2016; 32:815-826. [PMID: 27353113 DOI: 10.1080/08927014.2016.1198953] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 05/28/2016] [Indexed: 06/06/2023]
Abstract
Listeria monocytogenes is an important cause of human foodborne infections and its ability to form biofilms is a serious concern to the food industry. To reveal the effect of glucose conditions on biofilm formation of L. monocytogenes, 20 strains were investigated under three glucose conditions (0.1, 1.0, and 2.0% w v(-1)) by quantifying the number of cells in the biofilm and observing the biofilm structure after incubation for 24, 72, and 168 h. In addition, the biofilms were examined for their sensitivity to sodium hypochlorite. It was found that high concentrations of glucose reduced the number of viable cells in the biofilms and increased extracellular polymeric substance production. Moreover, biofilms formed at a glucose concentration of 1.0 or 2.0% were more resistant to sodium hypochlorite than those formed at a glucose concentration of 0.1%. This knowledge can be used to help design the most appropriate sanitation strategy.
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Affiliation(s)
- Daisuke Kyoui
- a Department of Food Science and Technology, Faculty of Marine Science , Tokyo University of Marine Science and Technology , Tokyo , Japan
| | - Eri Hirokawa
- a Department of Food Science and Technology, Faculty of Marine Science , Tokyo University of Marine Science and Technology , Tokyo , Japan
| | - Hajime Takahashi
- a Department of Food Science and Technology, Faculty of Marine Science , Tokyo University of Marine Science and Technology , Tokyo , Japan
| | - Takashi Kuda
- a Department of Food Science and Technology, Faculty of Marine Science , Tokyo University of Marine Science and Technology , Tokyo , Japan
| | - Bon Kimura
- a Department of Food Science and Technology, Faculty of Marine Science , Tokyo University of Marine Science and Technology , Tokyo , Japan
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20
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Zetzmann M, Okshevsky M, Endres J, Sedlag A, Caccia N, Auchter M, Waidmann MS, Desvaux M, Meyer RL, Riedel CU. DNase-Sensitive and -Resistant Modes of Biofilm Formation by Listeria monocytogenes. Front Microbiol 2015; 6:1428. [PMID: 26733972 PMCID: PMC4686886 DOI: 10.3389/fmicb.2015.01428] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 11/30/2015] [Indexed: 12/11/2022] Open
Abstract
Listeria monocytogenes is able to form biofilms on various surfaces and this ability is thought to contribute to persistence in the environment and on contact surfaces in the food industry. Extracellular DNA (eDNA) is a component of the biofilm matrix of many bacterial species and was shown to play a role in biofilm establishment of L. monocytogenes. In the present study, the effect of DNaseI treatment on biofilm formation of L. monocytogenes EGD-e was investigated under static and dynamic conditions in normal or diluted complex medium at different temperatures. Biofilm formation was quantified by crystal violet staining or visualized by confocal laser scanning microscopy. Biomass of surface-attached L. monocytogenes varies depending on temperature and dilution of media. Interestingly, L. monocytogenes EGD-e forms DNase-sensitive biofilms in diluted medium whereas in full strength medium DNaseI treatment had no effect. In line with these observations, eDNA is present in the matrix of biofilms grown in diluted but not full strength medium and supernatants of biofilms grown in diluted medium contain chromosomal DNA. The DNase-sensitive phenotype could be clearly linked to reduced ionic strength in the environment since dilution of medium in PBS or saline abolished DNase sensitivity. Several other but not all species of the genus Listeria display DNase-sensitive and -resistant modes of biofilm formation. These results indicate that L. monocytogenes biofilms are DNase-sensitive especially at low ionic strength, which might favor bacterial lysis and release of chromosomal DNA. Since low nutrient concentrations with increased osmotic pressure are conditions frequently found in food processing environments, DNaseI treatment represents an option to prevent or remove Listeria biofilms in industrial settings.
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Affiliation(s)
- Marion Zetzmann
- Institute of Microbiology and Biotechnology, University of Ulm Ulm, Germany
| | - Mira Okshevsky
- Interdisciplinary Nanoscience Center and Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Jasmin Endres
- Institute of Microbiology and Biotechnology, University of Ulm Ulm, Germany
| | - Anne Sedlag
- Institute of Microbiology and Biotechnology, University of Ulm Ulm, Germany
| | - Nelly Caccia
- INRA, UR454 Microbiologie Saint-Genès-Champanelle, France
| | - Marc Auchter
- Institute of Microbiology and Biotechnology, University of Ulm Ulm, Germany
| | - Mark S Waidmann
- Institute of Microbiology and Biotechnology, University of Ulm Ulm, Germany
| | | | - Rikke L Meyer
- Interdisciplinary Nanoscience Center and Department of Bioscience, Aarhus University Aarhus, Denmark
| | - Christian U Riedel
- Institute of Microbiology and Biotechnology, University of Ulm Ulm, Germany
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21
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Chen D, Zhao T, Doyle MP. Single- and mixed-species biofilm formation by Escherichia coli O157:H7 and Salmonella, and their sensitivity to levulinic acid plus sodium dodecyl sulfate. Food Control 2015. [DOI: 10.1016/j.foodcont.2015.04.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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22
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Nowak J, Cruz CD, Palmer J, Fletcher GC, Flint S. Biofilm formation of the L. monocytogenes strain 15G01 is influenced by changes in environmental conditions. J Microbiol Methods 2015; 119:189-95. [PMID: 26524221 DOI: 10.1016/j.mimet.2015.10.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 10/27/2015] [Accepted: 10/28/2015] [Indexed: 02/06/2023]
Abstract
Listeria monocytogenes 15G01, a strain belonging to the persistent pulsotype 5132, was isolated from a seafood processing plant in New Zealand. Simple monoculture assays using crystal violet staining showed good biofilm formation for this strain and it was therefore chosen to be further investigated in regard to its biofilm forming ability. To evaluate its behaviour in different conditions commonly encountered in food processing environments, biofilm assays and growth studies were performed using common laboratory media under a range of temperatures (20 °C, 30 °C and 37 °C). Furthermore, the effects of incubation time and different environmental conditions including static, dynamic and anaerobic incubation on biofilm formation were investigated. Changes in the environmental conditions resulted in different biofilm phenotypes of L. monocytogenes 15G01. We demonstrated that increasing temperature and incubation time led to a higher biofilm mass and that dynamic incubation has little effect on biofilm formation at 37 °C but encourages biofilm formation at 30 °C. Biofilm production at 20 °C was minimal regardless of the medium used. We furthermore observed that anaerobic environment led to reduced biofilm mass at 30 °C for all tested media but not at 37 °C. Biofilm formation could not be narrowed down to one factor but was rather dependent on multiple factors with temperature and medium having the biggest effects.
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Affiliation(s)
- Jessika Nowak
- The New Zealand Institute for Plant & Food Research Limited, Mt Albert, Auckland, New Zealand; Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand.
| | - Cristina D Cruz
- The New Zealand Institute for Plant & Food Research Limited, Mt Albert, Auckland, New Zealand
| | - Jon Palmer
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
| | - Graham C Fletcher
- The New Zealand Institute for Plant & Food Research Limited, Mt Albert, Auckland, New Zealand
| | - Steve Flint
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand
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23
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Yeater MC, Kirsch KR, Taylor TM, Mitchell J, Osburn WN. Effectiveness of sanitizing products on controlling selected pathogen surrogates on retail deli slicers. J Food Prot 2015; 78:707-15. [PMID: 25836395 DOI: 10.4315/0362-028x.jfp-14-400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The objectives of this study were (i) to assess the efficacy of quaternary ammonium chloride-based wet foam (WF) and dry foam (DF) sanitizer systems (600 ppm) for reducing Listeria innocua (a nonpathogenic surrogate of Listeria monocytogenes) or a 100.0 μg/ml rifampin-resistant Salmonella Typhimurium LT2 (a nonpathogenic surrogate of Salmonella enterica serovar Typhimurium) on niche and transfer point areas of an unwashed retail deli slicer as compared with traditional chlorine (Cl(-)) treatment (200 ppm) and (ii) to compare sanitizer surface contact times (10 and 15 min) for pathogen surrogate control. Turkey frankfurter slurries inoculated with L. innocua or Salmonella Typhimurium were used to inoculate seven high-risk sites on a commercial slicer. After 30 min of bacterial attachment, slicers were dry wiped to remove excess food matter, followed by a randomly assigned sanitizer treatment. Surviving pathogen surrogate cells were enumerated on modified Oxford's agar not containing antimicrobic supplement (L. innocua) or on tryptic soy agar supplemented with 100 μg/ml rifampin (Salmonella Typhimurium LT2). Replicate-specific L. innocua and Salmonella Typhimurium reductions were calculated as log CFU per square centimeter of control minus log CFU per square centimeter of enumerated survivors for each site. For both organisms, all sanitizer treatments differed from each other, with Cl(-) producing the least reduction and WF the greatest reduction. A significant (P < 0.05) site-by-treatment interaction was observed. The results of the study indicate that quaternary ammonium chloride sanitizers (600 ppm) applied by both WF and DF were more effective at reducing L. innocua and Salmonella Typhimurium than a traditional Cl sanitizer (200 ppm) on unwashed slicer surfaces.
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Affiliation(s)
- Michael C Yeater
- Department of Animal Science, Texas A&M AgriLife Research, Texas A&M University, College Station, Texas 77843-2471, USA
| | - Katie R Kirsch
- Department of Nutrition and Food Science, Texas A&M University, College Station, Texas 77843-2253, USA
| | - T Matthew Taylor
- Department of Animal Science, Department of Animal Science, Texas A&M AgriLife Research, Texas A&M University, College Station, Texas 77843-2471, USA
| | - Jeff Mitchell
- Chemstar Corporation, 120 Interstate West Parkway, Lithia Springs, Georgia 30122, USA
| | - Wesley N Osburn
- Department of Animal Science, Department of Animal Science, Texas A&M AgriLife Research, Texas A&M University, College Station, Texas 77843-2471, USA.
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24
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Melo J, Andrew P, Faleiro M. Listeria monocytogenes in cheese and the dairy environment remains a food safety challenge: The role of stress responses. Food Res Int 2015. [DOI: 10.1016/j.foodres.2014.10.031] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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25
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Ortiz S, López V, Martínez-Suárez JV. The influence of subminimal inhibitory concentrations of benzalkonium chloride on biofilm formation by Listeria monocytogenes. Int J Food Microbiol 2014; 189:106-12. [PMID: 25136789 DOI: 10.1016/j.ijfoodmicro.2014.08.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 07/19/2014] [Accepted: 08/02/2014] [Indexed: 12/14/2022]
Abstract
Disinfectants, such as benzalkonium chloride (BAC), are commonly used to control Listeria monocytogenes and other pathogens in food processing plants. Prior studies have demonstrated that the resistance to BAC of L. monocytogenes was associated with the prolonged survival of three strains of molecular serotype 1/2a in an Iberian pork processing plant. Because survival in such environments is related to biofilm formation, we hypothesised that the influence of BAC on the biofilm formation potential of L. monocytogenes might differ between BAC-resistant strains (BAC-R, MIC≥10mg/L) and BAC-sensitive strains (BAC-S, MIC≤2.5mg/L). To evaluate this possibility, three BAC-R strains and eight BAC-S strains, which represented all of the molecular serotype 1/2a strains detected in the sampled plant, were compared. Biofilm production was measured using the crystal violet staining method in 96-well microtitre plates. The BAC-R strains produced significantly (p<0.05) less biofilm than the BAC-S in the absence of BAC, independent of the rate of planktonic growth. In contrast, when the biofilm values were measured in the presence of BAC, one BAC-R strain (S10-1) was able to form biofilm at 5mg/L of BAC, which prevented biofilm formation among the rest of the strains. A genetic determinant of BAC resistance recently described in L. monocytogenes (Tn6188) was detected in S10-1. When a BAC-S strain and its spontaneous mutant BAC-R derivative were compared, resistance to BAC led to biofilm formation at 5mg/L of BAC and to a significant (p<0.05) stimulation of biofilm formation at 1.25mg/L of BAC, which significantly (p<0.05) reduced the biofilm level in the parent BAC-S strain. Our results suggest that the effect of subminimal inhibitory concentrations of BAC on biofilm production by L. monocytogenes might differ between strains with different MICs and even between resistant strains with similar MICs but different genetic determinants of BAC resistance. For BAC-R strains similar to S10-1, subminimal inhibitory BAC may represent an advantage, compensating for the weak biofilm formation level that might be associated with resistance. Biofilm formation in the presence of increased subminimal inhibitory concentrations of the disinfectant may represent an important attribute among certain resistant and persistent strains of L. monocytogenes.
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Affiliation(s)
- Sagrario Ortiz
- Departamento de Tecnología de Alimentos, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain
| | - Victoria López
- Departamento de Bioinformática y Salud Pública, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Joaquín V Martínez-Suárez
- Departamento de Tecnología de Alimentos, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain.
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26
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Chen M, Wu Q, Zhang J, Guo W, Wu S, Yang X. Prevalence and contamination patterns of Listeria monocytogenes in Flammulina velutipes plants. Foodborne Pathog Dis 2014; 11:620-7. [PMID: 24824447 DOI: 10.1089/fpd.2013.1727] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Four mushroom (Flammulina velutipes) production plants were sampled to investigate the prevalence and contamination source of Listeria monocytogenes. Among 295 samples, the prevalence of L. monocytogenes was 18.6%; the contamination appeared to originate from the mycelium-scraping machinery, contaminating both the product and upstream packaging equipment. Of 55 L. monocytogenes isolates, lineages I.1 (1/2a-3a) and II.2 (1/2b-3b-7) accounted for 65.5% and 34.5%, respectively. In addition, lineage I.1 formed significantly thicker biofilms than those within lineage II.2, as determined by crystal violet staining and scanning electron microscopy. Genotype analyses of L. monocytogenes isolates using enterobacteria repetitive intergenic consensus-polymerase chain reaction, and random amplified polymorphic DNA revealed that the surfaces of mycelium-scraping machinery may serve as the main source of L. monocytogenes contamination in three of the four plants. This study was the first report to explore the potential contamination sources of L. monocytogenes in the mushroom production chain, thereby providing baseline information for adopting prophylactic measures for critical control points during production in mushroom plants to avoid L. monocytogenes contamination.
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Affiliation(s)
- Moutong Chen
- 1 School of Bioscience and Bioengineering, South China University of Technology , Guangzhou, China
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27
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Gião MS, Keevil CW. Listeria monocytogenes can form biofilms in tap water and enter into the viable but non-cultivable state. MICROBIAL ECOLOGY 2014; 67:603-611. [PMID: 24452996 DOI: 10.1007/s00248-013-0364-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 12/27/2013] [Indexed: 06/03/2023]
Abstract
Listeria monocytogenes is a foodborne pathogen that can be transmitted through contaminated raw food or by ready-to-eat products that have been in contact with contaminated surfaces. Tap water (TW) is used to wash produce, as a processed food constituent and to wash processing surfaces and floors. The main aim of this work was to investigate the formation and survival of L. monocytogenes biofilms on stainless steel (SS) coupons in TW at 4, 22, 30 and 37 °C. For that, coupons with biofilm were visualised in situ while other coupons were scraped to quantify total cells by SYTO 9, cultivable numbers by plating onto brain heart infusion agar and viable numbers by the direct viable count method. Results showed that L. monocytogenes can form biofilms on SS surfaces in TW at any temperature, including at 4 °C. The number of total cells was similar for all the conditions tested while cultivable numbers varied between the level of detection (<8.3 CFU cm(-2)) and 3.5 × 10(5) CFU cm(-2), meaning between 7.0 × 10(4) and 1.1 × 10(7) cells cm(-2) have entered the viable but non-cultivable (VBNC) state. This work clearly demonstrates that L. monocytogenes can form biofilms in TW and that sessile cells can remain viable and cultivable in some conditions for at least the 48 h investigated. On the other hand, VBNC adaptation suggests that the pathogen can remain undetectable using traditional culture recovery techniques, which may give a false indication of processing surface hygiene status, leading to potential cross-contamination of food products.
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Affiliation(s)
- Maria S Gião
- Environmental Healthcare Unit, Centre for Biological Sciences, University of Southampton, Life Sciences Building, Highfield Campus, Southampton, SO17 1BJ, UK,
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Transcriptional analysis of genes related to biofilm formation, stress-response, and virulence in Listeria monocytogenes strains grown at different temperatures. ANN MICROBIOL 2014. [DOI: 10.1007/s13213-014-0814-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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29
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Valderrama WB, Ostiguy N, Cutter CN. Multivariate analysis reveals differences in biofilm formation capacity among Listeria monocytogenes lineages. BIOFOULING 2014; 30:1199-1209. [PMID: 25397897 DOI: 10.1080/08927014.2014.980818] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Biofilm formation capacity evaluated under identical conditions differs among Listeria monocytogenes lineages. The approach of using one set of factors or one variable at a time fails to explain why some lineages are more prevalent than others in certain environments. This study proposes the use of multivariate analysis to compare biofilm formation by various strains and describes the ecological niches of L. monocytogenes lineages. Nutrient availability, temperature, pH and water activity (aw) at three different levels were used to determine biofilm formation by 41 strains. Despite the high degree of similarity (≤ 80%), distinct lineage-associated biofilm formation patterns were identified. A linear regression model for each strain and a principal component analysis of regression coefficients indicated that Lineages I and III have different, but overlapping, ecological niches. This study is the first to report the use of multivariate analyses to compare biofilm formation by various isolates of L. monocytogenes.
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Affiliation(s)
- Wladir B Valderrama
- a Department of Food Science , Pennsylvania State University , University Park , PA , USA
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30
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Ochiai Y, Yamada F, Mochizuki M, Takano T, Hondo R, Ueda F. Biofilm formation under different temperature conditions by a single genotype of persistent Listeria monocytogenes strains. J Food Prot 2014; 77:133-40. [PMID: 24406011 DOI: 10.4315/0362-028x.jfp-13-074] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Some Listeria monocytogenes strains, termed persistent strains, originate from the same processing plant and have the ability to survive and grow over extended periods of time at contamination sources. In order to evaluate biofilm formation by such persistent strains, we isolated the pathogen from chicken samples collected from the same retail shop in repeated visits over 6 months. Strains that were of serotype 1/2b and were assigned to the same genotype by multi-virulence-locus sequence typing analysis were isolated on repeated occasions from December 1997 to June 1998 and thus were defined as persistent strains. In the present study, biofilm formation by the persistent strains was evaluated using microplates at 30 and 37°C. The biofilm-forming capability was measured after cells attaching to the microplate well were stained with crystal violet. Comparison of biofilm formation at 30°C among the persistent strains showed that a significantly higher amount of the stain was obtained from the persistent strains isolated from December to March than from those isolated from April to June. However, no significant difference in biofilm formation at 30°C was observed between persistent and nonpersistent groups of L. monocytogenes strains. In contrast, biofilm formation at 37°C was consistent among the persistent strains, and they produced significantly more biofilm at 37°C than did the nonpersistent strains. The persistent strains were also found to change their biofilm-forming ability in a temperature-dependent manner, which may suggest that the persistent strains alter their biofilm formation in response to changing environmental factors.
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Affiliation(s)
- Yoshitsugu Ochiai
- Department of Veterinary Science, Nippon Veterinary and Life Sciences University, Tokyo 180-8602, Japan
| | - Fumiya Yamada
- Department of Veterinary Science, Nippon Veterinary and Life Sciences University, Tokyo 180-8602, Japan; Saitama Institute of Public Health, Saitama 338-0824, Japan
| | - Mariko Mochizuki
- Department of Veterinary Nursing and Technology, Nippon Veterinary and Life Sciences University, Tokyo 180-8602, Japan
| | - Takashi Takano
- Department of Veterinary Science, Nippon Veterinary and Life Sciences University, Tokyo 180-8602, Japan
| | - Ryo Hondo
- Department of Veterinary Science, Nippon Veterinary and Life Sciences University, Tokyo 180-8602, Japan
| | - Fukiko Ueda
- Department of Veterinary Science, Nippon Veterinary and Life Sciences University, Tokyo 180-8602, Japan
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31
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Manios SG, Skandamis PN. Control of Listeria monocytogenes in the processing environment by understanding biofilm formation and resistance to sanitizers. Methods Mol Biol 2014; 1157:251-261. [PMID: 24792564 DOI: 10.1007/978-1-4939-0703-8_21] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Listeria monocytogenes can colonize in the food processing environment and thus pose a greater risk of cross-contamination to food. One of the proposed mechanisms that facilitates such colonization is biofilm formation. As part of a biofilm, it is hypothesized that L. monocytogenes can survive sanitization procedures. In addition, biofilms are difficult to remove and may require additional physical and chemical mechanisms to reduce their presence and occurrence. The initial stage of biofilm formation is attachment to surfaces, and therefore it is important to be able to determine the ability of L. monocytogenes strains to attach to various inert surfaces. In this chapter, methods to study bacterial attachment to surfaces are described. Attachment is commonly induced by bringing planktonic cells into contact with plastic, glass, or stainless steel surfaces with or without food residues ("soil") in batch or continuous (e.g., with constant flow of nutrients) culture. Measurement of biofilm formed is carried out by detaching cells (with various mechanical methods) and measuring the viable counts or by measuring the total attached biomass. Resistance of biofilms to sanitizers is commonly carried out by exposure of the whole model surface bearing the attached cells to a solution of sanitizer, followed by measuring the survivors as described above.
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Affiliation(s)
- Stavros G Manios
- Agricultural University of Athens, Iera Odos 75, Athens, 118 55, Greece
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32
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Ferreira V, Wiedmann M, Teixeira P, Stasiewicz MJ. Listeria monocytogenes persistence in food-associated environments: epidemiology, strain characteristics, and implications for public health. J Food Prot 2014; 77:150-70. [PMID: 24406014 DOI: 10.4315/0362-028x.jfp-13-150] [Citation(s) in RCA: 465] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Over the last 10 to 15 years, increasing evidence suggests that persistence of Listeria monocytogenes in food processing plants for years or even decades is an important factor in the transmission of this foodborne pathogen and the root cause of a number of human listeriosis outbreaks. L. monocytogenes persistence in other food-associated environments (e.g., farms and retail establishments) may also contribute to food contamination and transmission of the pathogen to humans. Although L. monocytogenes persistence is typically identified through isolation of a specific molecular subtype from samples collected in a given environment over time, formal (statistical) criteria for identification of persistence are undefined. Environmental factors (e.g., facilities and equipment that are difficult to clean) have been identified as key contributors to persistence; however, the mechanisms are less well understood. Although some researchers have reported that persistent strains possess specific characteristics that may facilitate persistence (e.g., biofilm formation and better adaptation to stress conditions), other researchers have not found significant differences between persistent and nonpersistent strains in the phenotypic characteristics that might facilitate persistence. This review includes a discussion of our current knowledge concerning some key issues associated with the persistence of L. monocytogenes, with special focus on (i) persistence in food processing plants and other food-associated environments, (ii) persistence in the general environment, (iii) phenotypic and genetic characteristics of persistent strains, (iv) niches, and (v) public health and economic implications of persistence. Although the available data clearly indicate that L. monocytogenes persistence at various stages of the food chain contributes to contamination of finished products, continued efforts to quantitatively integrate data on L. monocytogenes persistence (e.g., meta-analysis or quantitative microbial risk assessment) will be needed to advance our understanding of persistence of this pathogen and its economic and public health impacts.
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Affiliation(s)
- V Ferreira
- Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal; Department of Food Science, Cornell University, Ithaca, New York 14853, USA
| | - M Wiedmann
- Department of Food Science, Cornell University, Ithaca, New York 14853, USA
| | - P Teixeira
- Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal
| | - M J Stasiewicz
- Department of Food Science, Cornell University, Ithaca, New York 14853, USA
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Barbosa J, Borges S, Camilo R, Magalhães R, Ferreira V, Santos I, Silva J, Almeida G, Teixeira P. Biofilm Formation among Clinical and Food Isolates of Listeria monocytogenes. Int J Microbiol 2013; 2013:524975. [PMID: 24489549 PMCID: PMC3893795 DOI: 10.1155/2013/524975] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 10/07/2013] [Indexed: 11/18/2022] Open
Abstract
Objective. A total of 725 Listeria monocytogenes isolates, 607 from various foods and 118 from clinical cases of listeriosis, were investigated concerning their ability to form biofilms, at 4°C during 5 days and at 37°C during 24 h. Methods. Biofilm production was carried out on polystyrene tissue culture plates. Five L. monocytogenes isolates were tested for biofilm formation after being exposed to acidic and osmotic stress conditions. Results. Significant differences (P < 0.01) between clinical and food isolates were observed. At 37°C for 24 h, most food isolates were classified as weak or moderate biofilm formers whereas all the clinical isolates were biofilm producers, although the majority were weak. At 4°C during 5 days, 65 and 59% isolates, from food and clinical cases, respectively, were classified as weak. After both sublethal stresses, at 37°C just one of the five isolates tested was shown to be more sensitive to subsequent acidic exposure. However, at 4°C both stresses did not confer either sensitivity or resistance. Conclusions. Significant differences between isolates origin, temperature, and sublethal acidic stress were observed concerning the ability to form biofilms. Strain, origin, and environmental conditions can determine the level of biofilm production by L. monocytogenes isolates.
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Affiliation(s)
- Joana Barbosa
- Centro de Biotecnologia e Química Fina (CBQF), Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal
| | - Sandra Borges
- Centro de Biotecnologia e Química Fina (CBQF), Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal
| | - Ruth Camilo
- Centro de Biotecnologia e Química Fina (CBQF), Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal
| | - Rui Magalhães
- Centro de Biotecnologia e Química Fina (CBQF), Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal
| | - Vânia Ferreira
- Centro de Biotecnologia e Química Fina (CBQF), Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal
| | - Isabel Santos
- Centro de Biotecnologia e Química Fina (CBQF), Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal
| | - Joana Silva
- Centro de Biotecnologia e Química Fina (CBQF), Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal
| | - Gonçalo Almeida
- Centro de Biotecnologia e Química Fina (CBQF), Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal
| | - Paula Teixeira
- Centro de Biotecnologia e Química Fina (CBQF), Laboratório Associado, Escola Superior de Biotecnologia, Universidade Católica Portuguesa/Porto, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal
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34
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Daneshvar Alavi HE, Truelstrup Hansen L. Kinetics of biofilm formation and desiccation survival of Listeria monocytogenes in single and dual species biofilms with Pseudomonas fluorescens, Serratia proteamaculans or Shewanella baltica on food-grade stainless steel surfaces. BIOFOULING 2013; 29:1253-1268. [PMID: 24102145 DOI: 10.1080/08927014.2013.835805] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This study investigated the dynamics of static biofilm formation (100% RH, 15 °C, 48-72 h) and desiccation survival (43% RH, 15 °C, 21 days) of Listeria monocytogenes, in dual species biofilms with the common spoilage bacteria, Pseudomonas fluorescens, Serratia proteamaculans and Shewanella baltica, on the surface of food grade stainless steel. The Gram-negative bacteria reduced the maximum biofilm population of L. monocytogenes in dual species biofilms and increased its inactivation during desiccation. However, due to the higher desiccation resistance of Listeria relative to P. fluorescens and S. baltica, the pathogen survived in greater final numbers. In contrast, S. proteamaculans outcompeted the pathogen during the biofilm formation and exhibited similar desiccation survival, causing the N21 days of Serratia to be ca 3 Log10(CFU cm(-2)) greater than that of Listeria in the dual species biofilm. Microscopy revealed biofilm morphologies with variable amounts of exopolymeric substance and the presence of separate microcolonies. Under these simulated food plant conditions, the fate of L. monocytogenes during formation of mixed biofilms and desiccation depended on the implicit characteristics of the co-cultured bacterium.
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Affiliation(s)
- Hessam Edin Daneshvar Alavi
- a Food Science Program, Faculty of Engineering, Department of Process Engineering and Applied Science , Dalhousie University , Halifax , Canada
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35
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Salazar JK, Wu Z, Yang W, Freitag NE, Tortorello ML, Wang H, Zhang W. Roles of a novel Crp/Fnr family transcription factor Lmo0753 in soil survival, biofilm production and surface attachment to fresh produce of Listeria monocytogenes. PLoS One 2013; 8:e75736. [PMID: 24066185 PMCID: PMC3774658 DOI: 10.1371/journal.pone.0075736] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 08/16/2013] [Indexed: 11/18/2022] Open
Abstract
Listeria monocytogenes is a foodborne bacterial pathogen and the causative agent of an infectious disease, listeriosis. L. monocytogenes is ubiquitous in nature and has the ability to persist in food processing environments for extended periods of time by forming biofilms and resisting industrial sanitization. Human listeriosis outbreaks are commonly linked to contaminated dairy products, ready-to-eat meats, and in recent years, fresh produce such as lettuce and cantaloupes. We identified a putative Crp/Fnr family transcription factor Lmo0753 that is highly specific to human-associated genetic lineages of L. monocytogenes. Lmo0753 possesses two conserved functional domains similar to the major virulence regulator PrfA in L. monocytogenes. To determine if Lmo0753 is involved in environmental persistence-related mechanisms, we compared lmo0753 deletion mutants with respective wild type and complementation mutants of two fully sequenced L. monocytogenes genetic lineage II strains 10403S and EGDe for the relative ability of growth under different nutrient availability and temperatures, soil survival, biofilm productivity and attachment to select fresh produce surfaces including romaine lettuce leaves and cantaloupe rinds. Our results collectively suggested that Lmo0753 plays an important role in L. monocytogenes biofilm production and attachment to fresh produce, which may contribute to the environmental persistence and recent emergence of this pathogen in human listeriosis outbreaks linked to fresh produce.
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Affiliation(s)
- Joelle K. Salazar
- Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, Illinois, United States of America
| | - Zhuchun Wu
- Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, Illinois, United States of America
| | - Weixu Yang
- Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, Illinois, United States of America
| | - Nancy E. Freitag
- Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, Illinois, United States of America
| | - Mary Lou Tortorello
- United States Food and Drug Administration, Bedford Park, Illinois, United States of America
| | - Hui Wang
- Food Safety Research Center, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Wei Zhang
- Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, Illinois, United States of America
- School of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, China
- * E-mail:
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36
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Kadam SR, den Besten HM, van der Veen S, Zwietering MH, Moezelaar R, Abee T. Diversity assessment of Listeria monocytogenes biofilm formation: Impact of growth condition, serotype and strain origin. Int J Food Microbiol 2013; 165:259-64. [DOI: 10.1016/j.ijfoodmicro.2013.05.025] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 05/28/2013] [Accepted: 05/29/2013] [Indexed: 11/26/2022]
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37
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Biofilm formation, attachment, and cell hydrophobicity of foodborne pathogens under varied environmental conditions. ACTA ACUST UNITED AC 2013. [DOI: 10.1007/s13765-012-3253-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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38
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Lee HY, Chai LC, Pui CF, Mustafa S, Cheah YK, Nishibuchi M, Radu S. Formation of biofilm by Listeria monocytogenes ATCC 19112 at different incubation temperatures and concentrations of sodium chloride. Braz J Microbiol 2013; 44:51-5. [PMID: 24159283 PMCID: PMC3804177 DOI: 10.1590/s1517-83822013005000004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 09/30/2012] [Indexed: 12/04/2022] Open
Abstract
Biofilm formation can lead to various consequences in the food processing line such as contamination and equipment breakdowns. Since formation of biofilm can occur in various conditions; this study was carried out using L. monocytogenes ATCC 19112 and its biofilm formation ability tested under various concentrations of sodium chloride and temperatures. Cultures of L. monocytogenes ATCC 19112 were placed in 96-well microtitre plate containing concentration of sodium chloride from 1–10% (w/v) and incubated at different temperature of 4 °C, 30 °C and 45 °C for up to 60 h. Absorbance reading of crystal violet staining showed the density of biofilm formed in the 96-well microtitre plates was significantly higher when incubated in 4 °C. The formation of biofilm also occurs at a faster rate at 4 °C and higher optical density (OD 570 nm) was observed at 45 °C. This shows that storage under formation of biofilm that may lead to a higher contamination along the processing line in the food industry. Formation of biofilm was found to be more dependent on temperature compared to sodium chloride stress.
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Affiliation(s)
- H Y Lee
- Centre of Excellence for Food Safety Research, Faculty of Food Science and Technology, Universiti Putra Malaysia, Serdang, Selangor Darul Ehsan, Malaysia. ; Department of Molecular and Cellular Biology, Faculty of Biotechnology and Biomolecular Science, Universiti Putra Malaysia, Serdang, Selangor Darul Ehsan
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39
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Valderrama WB, Cutter CN. An Ecological Perspective ofListeria monocytogenesBiofilms in Food Processing Facilities. Crit Rev Food Sci Nutr 2013; 53:801-17. [DOI: 10.1080/10408398.2011.561378] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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40
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Susceptibility of Listeria monocytogenes biofilms and planktonic cultures to hydrogen peroxide in food processing environments. Biosci Biotechnol Biochem 2012; 76:2008-13. [PMID: 23132560 DOI: 10.1271/bbb.120238] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recent studies have indicated that Listeria monocytogenes formed biofilms on the surface of food processing equipment, and may survive sanitization treatments. The purpose of this study was to compare the susceptibility of L. monocytogenes grown in either a biofilm or planktonic culture when exposed to hydrogen peroxide (H(2)O(2)). Twelve strains of biofilm-forming L. monocytogenes and their planktonic counterparts were treated with various concentrations of H(2)O(2) (1, 6, and 10%), and the cell survival was then determined at 10-min exposure intervals. When grown as a biofilm, L. monocytogenes was significantly more resistant to H(2)O(2) than under planktonic culture conditions. Planktonic L. monocytogenes strains exhibited significantly different susceptibility to 1% H(2)O(2). Equally interestingly, biofilms of the 12 L. monocytogenes strains also inhibited different survival rates after being treated with 6 and 10% H(2)O(2). However, most of the biofilms recovered to a population of 2-9 log CFU/glass fiber filter (GFF) after a 24-h re-growth period. These results indicate that there was no significant correlation between the H(2)O(2) resistance of biofilm- and planktonic-cultured cells, and suggest that different mechanisms for the resistance to sanitation or disinfection underly the persistence of certain strains in food-processing environments.
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41
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Lourenço A, Rego F, Brito L, Frank JF. Evaluation of methods to assess the biofilm-forming ability of Listeria monocytogenes. J Food Prot 2012; 75:1411-7. [PMID: 22856564 DOI: 10.4315/0362-028x.jfp-11-464] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The contamination of ready-to-eat products with Listeria monocytogenes has been related to the presence of biofilms in production lines, as biofilms protect cells from chemical sanitizers. The ability of L. monocytogenes to produce biofilms is often evaluated using in vitro methodologies. This work aims to compare the most frequently used methodologies, including high-throughput screening methods based on microplates (crystal violet and the Calgary Biofilm Device) and methods based on CFU enumeration and microscopy after growth on stainless steel. Thirty isolates with diverse origins and genetic characteristics were evaluated. No (or low) correlations between methods were observed. The only significant correlation was found between the methods using stainless steel. No statistically significant correlation (P > 0.05) was detected among genetic lineage, serovar, and biofilm-forming ability. Because results indicate that biofilm formation is influenced by the surface material, the extrapolation of results from high-throughput methods using microplates to more industrially relevant surfaces should be undertaken with caution.
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Affiliation(s)
- António Lourenço
- Department of Food Science and Technology, University of Georgia, Athens, GA 30602, USA
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42
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Cruz CD, Fletcher GC. Assessing manufacturers' recommended concentrations of commercial sanitizers on inactivation of Listeria monocytogenes. Food Control 2012. [DOI: 10.1016/j.foodcont.2012.01.041] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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43
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Santopolo L, Marchi E, Frediani L, Decorosi F, Viti C, Giovannetti L. A novel approach combining the Calgary Biofilm Device and Phenotype MicroArray for the characterization of the chemical sensitivity of bacterial biofilms. BIOFOULING 2012; 28:1023-1032. [PMID: 23004019 DOI: 10.1080/08927014.2012.726352] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A rapid method for screening the metabolic susceptibility of biofilms to toxic compounds was developed by combining the Calgary Biofilm Device (MBEC device) and Phenotype MicroArray (PM) technology. The method was developed using Pseudomonas alcaliphila 34, a Cr(VI)-hyper-resistant bacterium, as the test organism. P. alcaliphila produced a robust biofilm after incubation for 16 h, reaching the maximum value after incubation for 24 h (9.4 × 10(6) ± 3.3 × 10(6) CFU peg(-1)). In order to detect the metabolic activity of cells in the biofilm, dye E (5×) and menadione sodium bisulphate (100 μM) were selected for redox detection chemistry, because they produced a high colorimetric yield in response to bacterial metabolism (340.4 ± 6.9 Omnilog Arbitrary Units). This combined approach, which avoids the limitations of traditional plate counts, was validated by testing the susceptibility of P. alcaliphila biofilm to 22 toxic compounds. For each compound the concentration level that significantly lowered the metabolic activity of the biofilm was identified. Chemical sensitivity analysis of the planktonic culture was also performed, allowing comparison of the metabolic susceptibility patterns of biofilm and planktonic cultures.
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Affiliation(s)
- L Santopolo
- Dipartimento di Biotecnologie Agrarie - sezione di Microbiologia and Laboratorio Genexpress, Università degli Studi di Firenze, Florence, Italy
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Szlavik J, Paiva DS, Mørk N, van den Berg F, Verran J, Whitehead K, Knøchel S, Nielsen DS. Initial adhesion of Listeria monocytogenes to solid surfaces under liquid flow. Int J Food Microbiol 2011; 152:181-8. [PMID: 21968113 DOI: 10.1016/j.ijfoodmicro.2011.09.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 09/01/2011] [Accepted: 09/04/2011] [Indexed: 01/19/2023]
Abstract
Some strains of the food borne pathogen Listeria monocytogenes persist in food processing environments. The exact reason behind this phenomenon is not known, but strain differences in the ability to adhere to solid surfaces could offer an explanation. In the present work, initial adhesion of nine strains of L. monocytogenes was investigated under liquid flow at two levels of shear stress on six different surfaces using a flow chamber set-up with microscopy measurements. The surfaces tested were glass and PVC, and glass coated with beef extract, casein, and homogenised and unhomogenised milk. In addition, the effect of prior environmental stress (5% NaCl, low nutrient availability) on initial adhesion was investigated. The hydrophobicity of the investigated surfaces was determined by contact angle measurements and the surface properties of the investigated L. monocytogenes strains were determined using Microbial Adhesion To Solvents (MATS). All surfaces with the exception of PVC were found to be hydrophilic. Strain differences were found to significantly influence the initial adhesion rate (IAR) of all nine strains to all the surfaces (p<0.05) at both low and high shear stress. Furthermore, there was a significant effect of the surfaces tested (p<0.05) in the adhesion ability of almost all strains. The IAR was affected by flow rate (shear stress) as seen by a decrease in adhesion at high shear stress for most strains. A significant effect of interactions between strain-surface and strain-shear stress (p<0.001) was observed but not of interactions between surface-shear stress. No correlation between surface hydrophobicity and IAR was observed. Addition of 5% NaCl during propagation resulted in a decrease in IAR whilst propagation in low nutrient media caused an increase indicating a general change in surface characteristics under these conditions. Known persisting strains did not display general better adherence.
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Affiliation(s)
- Julie Szlavik
- Department of Food Science, Food Microbiology, Faculty of Life Sciences, University of Copenhagen, Denmark
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Variability in biofilm production by Listeria monocytogenes correlated to strain origin and growth conditions. Int J Food Microbiol 2011; 150:14-24. [PMID: 21824672 DOI: 10.1016/j.ijfoodmicro.2011.07.012] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 04/18/2011] [Accepted: 07/04/2011] [Indexed: 11/20/2022]
Abstract
This study aimed to identify factors that influence the development of biofilm by Listeria monocytogenes strains and to determine the extent to which biofilm production protects against quaternary ammonium compound (QAC) disinfectant challenge. A total of 95 L. monocytogenes strains were studied and biofilm production was assessed as a function of incubation temperature, media pH, strain origin, serotype, and environmental persistence status. Attachment and biofilm development (inferred by the level of attached biomass) were measured in vitro using a colourimetric 96-well microtitre plate method in nutritive media (Brain-Heart Infusion). Increased biofilm production correlated with increasing temperature and the most acidic, or most alkaline, growth conditions tested. Clinical and environmental (food factory) strains were observed to increase biofilm production at higher and lower incubation temperatures respectively, independent of their rate of planktonic growth. Serotype 1/2a strains produced significantly more biofilm. Biofilm maturity, rather than strain, was correlated with resistance to QAC. Carbohydrate containing exopolymeric material could not be detected in the biofilm of representative strains, and no correlation between strains recovered as persistent food factory contaminants and biofilm production was identified. Although limited to in vitro inference based on the assay system used, our results suggest that environmental conditions determine the level of biofilm production by L. monocytogenes strains, independent of the rate of planktonic growth, and that this may manifest from selection pressures to which a given strain grows optimally.
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Cruz CD, Fletcher GC. Prevalence and biofilm-forming ability of Listeria monocytogenes in New Zealand mussel (Perna canaliculus) processing plants. Food Microbiol 2011; 28:1387-93. [PMID: 21839390 DOI: 10.1016/j.fm.2011.06.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 06/10/2011] [Accepted: 06/22/2011] [Indexed: 10/18/2022]
Abstract
Greenshell™ mussels are New Zealand's largest seafood export species. Some export markets require compliance with 'zero' tolerance legislation for Listeria monocytogenes in 25 g of product. Even though individually quick frozen (IQF) mussel products are labeled 'to be cooked', and are not classified as ready-to-eat, some markets still require them to comply with the strict policy. Three mussel processing plants were assessed for the pattern of L. monocytogenes contamination on raw material, environment, food contact surfaces, and in the final product. Cultures (n = 101) obtained from an industrial Listeria monitoring program from August 2007 to June 2009 were characterized by serotyping and pulsed field gel electrophoresis. Using the crystal violet method, isolates were assessed for their ability to form biofilms. This work confirmed the presence of L. monocytogenes in raw and processed product, and the importance of cross-contamination from external and internal environments. Processing plants had L. monocytogenes pulsotypes that were detected more than once over 6 months. No correlation was found between biofilm-forming ability and persistent isolates. Two pulsotypes (including a persistent one), were previously isolated in human cases of listeriosis in New Zealand, but none of the pulsotypes matched those involved in international outbreaks.
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Affiliation(s)
- Cristina D Cruz
- The New Zealand Institute for Plant & Food Research Limited, Auckland 1025, New Zealand.
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Verghese B, Lok M, Wen J, Alessandria V, Chen Y, Kathariou S, Knabel S. comK prophage junction fragments as markers for Listeria monocytogenes genotypes unique to individual meat and poultry processing plants and a model for rapid niche-specific adaptation, biofilm formation, and persistence. Appl Environ Microbiol 2011; 77:3279-92. [PMID: 21441318 PMCID: PMC3126449 DOI: 10.1128/aem.00546-11] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Accepted: 03/14/2011] [Indexed: 12/21/2022] Open
Abstract
Different strains of Listeria monocytogenes are well known to persist in individual food processing plants and to contaminate foods for many years; however, the specific genotypic and phenotypic mechanisms responsible for persistence of these unique strains remain largely unknown. Based on sequences in comK prophage junction fragments, different strains of epidemic clones (ECs), which included ECII, ECIII, and ECV, were identified and shown to be specific to individual meat and poultry processing plants. The comK prophage-containing strains showed significantly higher cell densities after incubation at 30°C for 48 h on meat and poultry food-conditioning films than did strains lacking the comK prophage (P < 0.05). Overall, the type of strain, the type of conditioning film, and the interaction between the two were all highly significant (P < 0.001). Recombination analysis indicated that the comK prophage junction fragments in these strains had evolved due to extensive recombination. Based on the results of the present study, we propose a novel model in which the concept of defective comK prophage was replaced with the rapid adaptation island (RAI). Genes within the RAI were recharacterized as "adaptons," as these genes may allow L. monocytogenes to rapidly adapt to different food processing facilities and foods. If confirmed, the model presented would help explain Listeria's rapid niche adaptation, biofilm formation, persistence, and subsequent transmission to foods. Also, comK prophage junction fragment sequences may permit accurate tracking of persistent strains back to and within individual food processing operations and thus allow the design of more effective intervention strategies to reduce contamination and enhance food safety.
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Affiliation(s)
- Bindhu Verghese
- Department of Food Science, The Pennsylvania State University, University Park, PA 16802, USA.
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Takahashi H, Kuramoto S, Miya S, Kimura B. Desiccation survival of Listeria monocytogenes and other potential foodborne pathogens on stainless steel surfaces is affected by different food soils. Food Control 2011. [DOI: 10.1016/j.foodcont.2010.09.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Patel J, Sharma M, Ravishakar S. Effect of curli expression and hydrophobicity of Escherichia coli O157:H7 on attachment to fresh produce surfaces. J Appl Microbiol 2011; 110:737-45. [PMID: 21205101 DOI: 10.1111/j.1365-2672.2010.04933.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM To investigate the effect of curli expression on cell hydrophobicity, biofilm formation and attachment to cut and intact fresh produce surfaces. METHODS AND RESULTS Five Escherichia coli O157:H7 strains were evaluated for curli expression, hydrophobicity, biofilm formation and attachment to intact and cut fresh produce (cabbage, iceberg lettuce and Romaine lettuce) leaves. Biofilm formation was stronger when E. coli O157:H7 were grown in diluted tryptic soy broth (1:10). In general, strong curli-expressing E. coli O157:H7 strains 4406 and 4407 were more hydrophobic and attached to cabbage and iceberg lettuce surfaces at significantly higher numbers than other weak curli-expressing strains. Overall, E. coli O157:H7 populations attached to cabbage and lettuce (iceberg and Romaine) surfaces were similar (P>0·05), indicating produce surfaces did not affect (P<0·05) bacterial attachment. All E. coli O157:H7 strains attached rapidly on intact and cut produce surfaces. Escherichia coli O157:H7 attached preferentially to cut surfaces of all produce types; however, the difference between E. coli O157:H7 populations attached to intact and cut surfaces was not significant (P>0·05) in most cases. Escherichia coli O157:H7 attachment and attachment strength (S(R) ) to intact and cut produce surfaces increased with time. CONCLUSIONS Curli-producing E. coli O157:H7 strains attach at higher numbers to produce surfaces. Increased attachment of E. coli O157:H7 on cut surfaces emphasizes the need for an effective produce wash to kill E. coli O157:H7 on produce. SIGNIFICANCE AND IMPACT OF THE STUDY Understanding the attachment mechanisms of E. coli O157:H7 to produce surfaces will aid in developing new intervention strategies to prevent produce outbreaks.
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Affiliation(s)
- J Patel
- USDA, Agricultural Research Service, Environmental and Microbial Food Safety Laboratory, Beltsville, MA 20705-2350, USA.
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Patel J, Sharma M, Ravishakar S. Effect of curli expression and hydrophobicity of Escherichia coli O157:H7 on attachment to fresh produce surfaces. J Appl Microbiol 2011. [DOI: 10.1111/j.1365-2672.2011.04933.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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