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Yeo J, Jeon YW. Impact of Polyethylene-Glycol-Induced Water Potential on Methane Yield and Microbial Consortium Dynamics in the Anaerobic Degradation of Glucose. Bioengineering (Basel) 2024; 11:433. [PMID: 38790299 PMCID: PMC11117670 DOI: 10.3390/bioengineering11050433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 04/17/2024] [Accepted: 04/24/2024] [Indexed: 05/26/2024] Open
Abstract
This study investigated the relationship between water potential (Ψ) and the cation-induced inhibition of methane production in anaerobic digesters. The Ψ around methanogens was manipulated using polyethylene glycol (PEG) in a batch anaerobic reactor, ranging from -0.92 to -5.10 MPa. The ultimate methane potential (Bu) decreased significantly from 0.293 to 0.002 Nm3 kg-1-VSadded as Ψ decreased. When Ψ lowered from -0.92 MPa to -1.48 MPa, the community distribution of acetoclastic Methanosarcina decreased from 59.62% to 40.44%, while those of hydrogenotrophic Methanoculleus and Methanobacterium increased from 17.70% and 1.30% to 36.30% and 18.07%, respectively. These results mirrored changes observed in methanogenic communities affected by cation inhibition with KCl. Our findings strongly indicate that the inhibitory effect of cations on methane production may stem more from the water stress induced by cations than from their direct toxic effects. This study highlights the importance of considering Ψ dynamics in understanding cation-mediated inhibition in anaerobic digesters, providing insights into optimizing microbial processes for enhanced methane production from organic substrates.
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Affiliation(s)
- Jin Yeo
- Biogas Research Center, Hankyong National University, Anseong 17579, Republic of Korea;
| | - Yong-Woo Jeon
- Environmental Technology Division, Korea Testing Laboratory, Seoul 08389, Republic of Korea
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Exploring the Diversity of Biofilm Formation by the Food Spoiler Brochothrix thermosphacta. Microorganisms 2022; 10:microorganisms10122474. [PMID: 36557727 PMCID: PMC9785830 DOI: 10.3390/microorganisms10122474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/11/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022] Open
Abstract
Brochothrix thermosphacta is considered as a major spoiler of meat and seafood products. This study explores the biofilm formation ability and the biofilm structural diversity of 30 multi-origin B. thermosphacta strains using a set of complementary biofilm assays (biofilm ring test, crystal violet staining, and confocal laser scanning microscopy). Two major groups corresponding to low and high biofilm producers were identified. High biofilm producers presented flat architectures characterized by high surface coverage, high cell biovolume, and high surface area.
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Bacteria of eleven different species isolated from biofilms in a meat processing environment have diverse biofilm forming abilities. Int J Food Microbiol 2021; 349:109232. [PMID: 34022615 DOI: 10.1016/j.ijfoodmicro.2021.109232] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/16/2021] [Accepted: 04/25/2021] [Indexed: 11/23/2022]
Abstract
Biofilms are formed by microorganisms protected by a self-produced matrix, most often attached to a surface. In the food processing environments biofilms endanger the product safety by the transmission of spoilage and pathogenic bacteria. In this study, we characterised the biofilm formation of the following eleven strains isolated from biofilms in a meat-processing environment: Acinetobacter harbinensis BF1, Arthrobacter sp. BF1, Brochothrix thermosphacta BF1, Carnobacterium maltaromaticum BF1, Kocuria salsicia BF1, Lactococcus piscium BF1, Microbacterium sp. BF1, Pseudomonas fragi BF1, Psychrobacter sp. BF1, Rhodococcus erythropolis BF1, Stenotrophomonas sp. BF1. We applied whole- genome sequencing and subsequent genome analysis to elucidate genetic features associated with the biofilm lifestyle. We furthermore determined the motility and studied biofilm formation on stainless steel using a static mono-species biofilm model mimicking the meat processing environment. The biomass and the EPS components carbohydrates, proteins and extracellular DNA (eDNA) of the biofilms were investigated after seven days at 10 °C. Whole-genome analysis of the isolates revealed that all strains except the Kocuria salsicia BF1 isolate, harboured biofilm associated genes, including genes for matrix production and motility. Genes involved in cellulose metabolism (present in 82% of the eleven strains) and twitching motility (present in 45%) were most frequently found. The capacity for twitching was confirmed using plate assays for all strains except Lactococcus piscium BF1, which showed the lowest motility behaviour. Differences in biofilm forming abilities could be demonstrated. The bacterial load ranged from 5.4 log CFU/cm2 (Psychrobacter sp. isolate) to 8.7 log CFU/cm2 (Microbacterium sp. isolate). The amount of the matrix components varied between isolates. In the biofilm of six strains we detected all three matrix components at different levels (carbohydrates, proteins and eDNA), in two only carbohydrates and eDNA, and in three only carbohydrates. Carbohydrates were detected in biofilms of all strains ranging from 0.5 to 4.3 μg glucose equivalents/cm2. Overall, the Microbacterium sp. strain showed the highest biofilm forming ability with high bacterial load (8.7 log CFU/cm2) and high amounts of carbohydrates (2.2 μg glucose equivalents/cm2), proteins (present in all experiments) and eDNA (549 ng/cm2). In contrast, Brochothrix thermosphacta was a weak biofilm former, showing low bacterial load and low levels of carbohydrates in the matrix (6.2 log CFU/cm2 and 0.5 μg glucose equivalents/cm2). This study contributes to our understanding of the biofilm forming ability of bacteria highly abundant in the meat processing environment, which is crucial to develop strategies to prevent and reduce biofilm formation in the food producing environment.
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Chen CY, Nguyen LHT, Paoli GC, Irwin PL. The complex multicellular morphology of the food spoilage bacteria Brochothrix thermosphacta strains isolated from ground chicken. Can J Microbiol 2020; 66:303-312. [DOI: 10.1139/cjm-2019-0502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Herein we describe a highly structured, filamentous growth phenotype displayed by an isolate of the food spoilage microorganism Brochothrix thermosphacta. The growth morphology of this B. thermosphacta strain (strain BII) was dependent on environmental factors such as the growth media, incubation temperatures, and the inoculum concentration. Inoculation of cultures in highly dilute suspensions resulted in the formation of isolated, tight aggregates resembling fungal growth in liquid media. This same strain also formed stable, mesh-like structures in 6-well tissue culture plates under specific growth conditions. The complex growth phenotype does not appear to be unique to strain BII but was common among B. thermosphacta strains isolated from chicken. Light and electron micrographs showed that the filaments of multiple BII cells can organize into complex, tertiary structures resembling multistranded cables. Time-lapse microscopy was employed to monitor the development of such aggregates over 18 h and revealed growth originating from short filaments into compact ball-like clusters that appeared fuzzy due to protruding filaments or cables. This report is the first to document this complex filamentous growth phenotype in a wild-type bacterial isolate of B. thermosphacta.
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Affiliation(s)
- Chin-Yi Chen
- US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center Molecular Characterization of Foodborne Pathogens Research Unit, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center Molecular Characterization of Foodborne Pathogens Research Unit, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
| | - Ly-Huong T. Nguyen
- US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center Molecular Characterization of Foodborne Pathogens Research Unit, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center Molecular Characterization of Foodborne Pathogens Research Unit, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
| | - George C. Paoli
- US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center Molecular Characterization of Foodborne Pathogens Research Unit, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center Molecular Characterization of Foodborne Pathogens Research Unit, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
| | - Peter L. Irwin
- US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center Molecular Characterization of Foodborne Pathogens Research Unit, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
- US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center Molecular Characterization of Foodborne Pathogens Research Unit, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA
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Role of CpxR in Biofilm Development: Expression of Key Fimbrial, O-Antigen and Virulence Operons of Salmonella Enteritidis. Int J Mol Sci 2019; 20:ijms20205146. [PMID: 31627387 PMCID: PMC6829429 DOI: 10.3390/ijms20205146] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/06/2019] [Accepted: 10/15/2019] [Indexed: 01/05/2023] Open
Abstract
Salmonella Enteritidis is a non-typhoidal serovar of great public health significance worldwide. The RpoE sigma factor and CpxRA two-component system are the major regulators of the extracytoplasmic stress response. In this study, we found that the CpxR has highly significant, but opposite effects on the auto-aggregation and swarming motility of S. Enteritidis. Auto-aggregation was negatively affected in the ∆cpxR mutant, whereas the same mutant significantly out-performed its wild-type counterpart with respect to swarming motility, indicating that the CpxR plays a role in biofilm-associated phenotypes. Indeed, biofilm-related assays showed that the CpxR is of critical importance in biofilm development under both static (microtiter plate) and dynamic (flow cell) media flow conditions. In contrast, the RpoE sigma factor showed no significant role in biofilm development under dynamic conditions. Transcriptomic analysis revealed that the cpxR mutation negatively affected the constitutive expression of the operons critical for biosynthesis of O-antigen and adherence, but positively affected the expression of virulence genes critical for Salmonella-mediated endocytosis. Conversely, CpxR induced the expression of curli csgAB and fimbrial stdAC operons only during biofilm development and flagellar motAB and fliL operons exclusively during the planktonic phase, indicating a responsive biofilm-associated loop of the CpxR regulator.
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Giaouris E, Heir E, Hébraud M, Chorianopoulos N, Langsrud S, Møretrø T, Habimana O, Desvaux M, Renier S, Nychas GJ. Attachment and biofilm formation by foodborne bacteria in meat processing environments: causes, implications, role of bacterial interactions and control by alternative novel methods. Meat Sci 2013; 97:298-309. [PMID: 23747091 DOI: 10.1016/j.meatsci.2013.05.023] [Citation(s) in RCA: 217] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Revised: 05/15/2013] [Accepted: 05/16/2013] [Indexed: 12/19/2022]
Abstract
Attachment of potential spoilage and pathogenic bacteria to food contact surfaces and the subsequent biofilm formation represent serious challenges to the meat industry, since these may lead to cross-contamination of the products, resulting in lowered-shelf life and transmission of diseases. In meat processing environments, microorganisms are sometimes associated to surfaces in complex multispecies communities, while bacterial interactions have been shown to play a key role in cell attachment and detachment from biofilms, as well as in the resistance of biofilm community members against antimicrobial treatments. Disinfection of food contact surfaces in such environments is a challenging task, aggravated by the great antimicrobial resistance of biofilm associated bacteria. In recent years, several alternative novel methods, such as essential oils and bacteriophages, have been successfully tested as an alternative means for the disinfection of microbial-contaminated food contact surfaces. In this review, all these aspects of biofilm formation in meat processing environments are discussed from a microbial meat-quality and safety perspective.
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Affiliation(s)
- Efstathios Giaouris
- Department of Food Science and Nutrition, University of the Aegean, Myrina, Lemnos 81400, Greece.
| | - Even Heir
- Nofima Mat AS, Osloveien 1, N-1430 Ås, Norway
| | - Michel Hébraud
- Institut National de la Recherche Agronomique, site de Theix, UR454 Microbiologie, F-63122 Saint-Genès Champanelle, France
| | - Nikos Chorianopoulos
- Veterinary Research Institute of Athens, Greek Agricultural Organization "Demeter", Aghia Paraskeui15310, Greece
| | | | | | | | - Mickaël Desvaux
- Institut National de la Recherche Agronomique, site de Theix, UR454 Microbiologie, F-63122 Saint-Genès Champanelle, France
| | - Sandra Renier
- Institut National de la Recherche Agronomique, site de Theix, UR454 Microbiologie, F-63122 Saint-Genès Champanelle, France
| | - George-John Nychas
- Laboratory of Microbiology and Biotechnology of Foods, Department of Food Science and Technology, Agricultural University of Athens, Iera Odos 75, Athens 11855, Greece
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Pan Z, Carter B, Núñez-García J, AbuOun M, Fookes M, Ivens A, Woodward MJ, Anjum MF. Identification of genetic and phenotypic differences associated with prevalent and non-prevalent Salmonella Enteritidis phage types: analysis of variation in amino acid transport. MICROBIOLOGY-SGM 2009; 155:3200-3213. [PMID: 19574306 DOI: 10.1099/mic.0.029405-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this study, differences at the genetic level of 37 Salmonella Enteritidis strains from five phage types (PTs) were compared using comparative genomic hybridization (CGH) to assess differences between PTs. There were approximately 400 genes that differentiated prevalent (4, 6, 8 and 13a) and sporadic (11) PTs, of which 35 were unique to prevalent PTs, including six plasmid-borne genes, pefA, B, C, D, srgC and rck, and four chromosomal genes encoding putative amino acid transporters. Phenotype array studies also demonstrated that strains from prevalent PTs were less susceptible to urea stress and utilized l-histidine, l-glutamine, l-proline, l-aspartic acid, gly-asn and gly-gln more efficiently than PT11 strains. Complementation of a PT11 strain with the transporter genes from PT4 resulted in a significant increase in utilization of the amino acids and reduced susceptibility to urea stress. In epithelial cell association assays, PT11 strains were less invasive than other prevalent PTs. Most strains from prevalent PTs were better biofilm formers at 37 degrees C than at 28 degrees C, whilst the converse was true for PT11 strains. Collectively, the results indicate that genetic and corresponding phenotypic differences exist between strains of the prevalent PTs 4, 6, 8 and 13a and non-prevalent PT11 strains that are likely to provide a selective advantage for strains from the former PTs and could help them to enter the food chain and cause salmonellosis.
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Affiliation(s)
- Zhensheng Pan
- School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK.,Department of Food and Environmental Safety, Veterinary Laboratories Agency-Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Ben Carter
- Department of Food and Environmental Safety, Veterinary Laboratories Agency-Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Javier Núñez-García
- Department of Food and Environmental Safety, Veterinary Laboratories Agency-Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Manal AbuOun
- Department of Food and Environmental Safety, Veterinary Laboratories Agency-Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - María Fookes
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Al Ivens
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Martin J Woodward
- Department of Food and Environmental Safety, Veterinary Laboratories Agency-Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK
| | - Muna F Anjum
- Department of Food and Environmental Safety, Veterinary Laboratories Agency-Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK
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Rieu A, Briandet R, Habimana O, Garmyn D, Guzzo J, Piveteau P. Listeria monocytogenes EGD-e biofilms: no mushrooms but a network of knitted chains. Appl Environ Microbiol 2008; 74:4491-7. [PMID: 18502930 PMCID: PMC2493181 DOI: 10.1128/aem.00255-08] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Accepted: 05/13/2008] [Indexed: 11/20/2022] Open
Abstract
Listeria monocytogenes is a food pathogen that can attach on most of the surfaces encountered in the food industry. Biofilms are three-dimensional microbial structures that facilitate the persistence of pathogens on surfaces, their resistance toward antimicrobials, and the final contamination of processed goods. So far, little is known about the structural dynamics of L. monocytogenes biofilm formation and its regulation. The aims of this study were, by combining genetics and time-lapse laser-scanning confocal microscopy (LSCM), (i) to characterize the structural dynamics of L. monocytogenes EGD-e sessile growth in two nutritional environments (with or without a nutrient flow), and (ii) to evaluate the possible role of the L. monocytogenes agr system during biofilm formation by tracking the spatiotemporal fluorescence expression of a green fluorescent protein (GFP) reporter system. In the absence of nutrient flow (static conditions), unstructured biofilms composed of a few layers of cells that covered the substratum were observed. In contrast, when grown under dynamic conditions, L. monocytogenes EGD-e biofilms were highly organized. Indeed, ball-shaped microcolonies were surrounded by a network of knitted chains. The spatiotemporal tracking of fluorescence emitted by the GFP reporter system revealed that agr expression was barely detectable under static conditions, but it progressively increased during 40 h under dynamic conditions. Moreover, spatial analysis revealed that agr was expressed preferentially in cells located outside the microcolonies. Finally, the in-frame deletion of agrA, which encodes a transcriptional regulator, resulted in a decrease in initial adherence without affecting the subsequent biofilm development.
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Affiliation(s)
- Aurélie Rieu
- Laboratoire de Recherche En Vigne et Vin, Université de Bourgogne, IUVV, F-21000 Dijon, France
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Mangalappalli-Illathu AK, Lawrence JR, Swerhone GD, Korber DR. Architectural adaptation and protein expression patterns of Salmonella enterica serovar Enteritidis biofilms under laminar flow conditions. Int J Food Microbiol 2008; 123:109-20. [DOI: 10.1016/j.ijfoodmicro.2007.12.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Revised: 12/04/2007] [Accepted: 12/18/2007] [Indexed: 09/30/2022]
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Rodriguez A, Autio WR, McLandsborough LA. Effect of surface roughness and stainless steel finish on Listeria monocytogenes attachment and biofilm formation. J Food Prot 2008; 71:170-5. [PMID: 18236679 DOI: 10.4315/0362-028x-71.1.170] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The purpose of this study was to evaluate the effect of surface roughness (Ra) and finish of mechanically polished stainless steel (Ra = 0.26 +/- 0.05, 0.49 +/- 0.10, and 0.69 +/- 0.05 microm) and electropolished stainless steel (Ra = 0.16 +/- 0.06, 0.40 +/- 0.003, and 0.67 +/- 0.02 microm) on Listeria adhesion and biofilm formation. A four-strain cocktail of Listeria monocytogenes was used. Each strain (0.1%) was added to 200 ml of tryptic soy broth (TSB), and coupons were inserted to the mixture for 5 min. For biofilm formation, coupons with adhesive cells were incubated in 1:20 diluted TSB at 32 degrees C for 48 h. The experiment was performed by a randomized block design. Our results show that the level of Listeria present after 48 h of incubation (mean = 7 log CFU/cm2) was significantly higher than after 5 min (mean = 6.0 log CFU/cm2) (P < 0.01). No differences in initial adhesion were seen in mechanically finished (mean = 6.7 log CFU/cm2) when compared with electropolished stainless steel (mean = 6.7 log CFU/cm2) (P > 0.05). Listeria initial adhesion (values ranged from 5.9 to 6.1 log CFU/cm2) or biofilm formation (values ranged from 6.9 to 7.2 log CFU/cm2) was not significantly correlated with Ra values (P > 0.05). Image analysis with an atomic force microscope showed that bacteria did not colonize the complete surface after 48 h but were individual cells or grouped in microcolonies that ranged from 5 to 10 microm in diameter and one to three cell layers in thickness. Exopolymeric substances were observed to be associated with the colonies. According to our results, electropolishing stainless steel does not pose a significant advantage for food sanitation over mechanically finished stainless steel.
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Affiliation(s)
- Andres Rodriguez
- Department of Food Science, University of Massachusetts, 100 Holdsworth Way, Chenoweth Laboratory, Amherst, Massachusetts 01003, USA
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Mangalappalli-Illathu AK, Korber DR. Adaptive resistance and differential protein expression of Salmonella enterica serovar Enteritidis biofilms exposed to benzalkonium chloride. Antimicrob Agents Chemother 2006; 50:3588-96. [PMID: 16940079 PMCID: PMC1635200 DOI: 10.1128/aac.00573-06] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 06/02/2006] [Accepted: 08/18/2006] [Indexed: 01/05/2023] Open
Abstract
The development of adaptive resistance of Salmonella enterica serovar Enteritidis ATCC 4931 biofilms following exposure to benzalkonium chloride (BC) either continuously (1 microg ml(-1)) or intermittently (10 microg ml(-1) for 10 min daily) was examined. Biofilms adapted to BC over a 144-h period could survive a normally lethal BC challenge (500 microg ml(-1) for 10 min) and then regrow, as determined by increases in biofilm thickness, total biomass, and the ratio of the viable biomass to the nonviable biomass. Exposure of untreated control biofilms to the lethal BC challenge resulted in biofilm erosion and cell death. Proteins found to be up-regulated following BC adaptation were those involved in energy metabolism (TpiA and Eno), amino acid and protein biosynthesis (WrbA, TrxA, RplL, Tsf, Tuf, DsbA, and RpoZ), nutrient binding (FruB), adaptation (CspA), detoxification (Tpx, SodB, and a probable peroxidase), and degradation of 1,2-propanediol (PduJ and PduA). A putative universal stress protein (YnaF) was also found to be up-regulated. Proteins involved in proteolysis (DegQ), cell envelope formation (RfbH), adaptation (UspA), heat shock response (DnaK), and broad regulatory functions (Hns) were found to be down-regulated following adaptation. An overall increase in cellular protein biosynthesis was deduced from the significant up-regulation of ribosomal subunit proteins, translation elongation factors, and amino acid biosynthesis protein and down-regulation of serine endoprotease. The cold shock response, stress response, and detoxification are suggested to play roles in the adaptive resistance of Salmonella serovar Enteritidis biofilms to BC.
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Affiliation(s)
- Anil K Mangalappalli-Illathu
- Department of Applied Microbiology and Food Science, 51 Campus Dr., University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada
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Thévenot D, Dernburg A, Vernozy-Rozand C. An updated review of Listeria monocytogenes in the pork meat industry and its products. J Appl Microbiol 2006; 101:7-17. [PMID: 16834586 DOI: 10.1111/j.1365-2672.2006.02962.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Pork meat and processed pork products have been the sources of outbreaks of listeriosis in France and in other European countries during the last decade. The aim of this review is to understand how contamination, survival and growth of Listeria monocytogenes can occur in pork meat products. This study discusses the presence of L. monocytogenes in raw pork meat, in the processing environment and in finished products. The prevalence of L. monocytogenes generally increases from the farm to the manufacturing plants and this mainly due to cross-contamination. In many cases, this pathogen is present in raw pork meat at low or moderate levels, but foods involved in listeriosis outbreaks are those in which the organism has multiplied to reach levels significantly higher than 1000 CFU g(-1). In such cases, L. monocytogenes has been able to survive and/or to grow despite the hurdles encountered during the manufacturing and conservation processes. Accordingly, attention must be paid to the design of food-processing equipment and to the effectiveness of the cleaning and disinfecting procedures in factories. Finally, the production of safe pork meat products is based on the implementation of general preventive measures such as Good Hygiene Practices, Good Manufacturing and the Hazard Analysis Critical Control Point.
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Affiliation(s)
- D Thévenot
- Unité de Microbiologie Alimentaire et Prévisionnelle, Ecole Nationale Vétérinaire de Lyon, Marcy l'étoile, France.
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Abstract
Eight strains of Listeria monocytogenes (7644, 19112, 15313, Scott A, LCDC, 10403S, SLCC, and 1370) produce biofilms when grown on polyvinyl chloride microtiter well plates. The growth medium (tryptic soy broth [TSB] or modified Welshimer's broth [MWB] at 32 degrees C) influenced the amount of biofilm formed; maximum biofilms were formed in MWB by six strains and in TSB by the remaining two strains. This result suggests that the growth medium is critical in development of L. monocytogenes biofilm. This organism also produced biofilms on stainless steel chips. Biofilm formation on these chips was observed following growth in TSB at 4, 20, and 37 degrees C. After 20 h of incubation at 20 or 37 degrees C, the cell density was approximately 10(6) CFU per chip, and after 4 days incubation at 4 degrees C, the cell density was 10(5) CFU per chip. L. monocytogenes strain Scott A biofilm formation on stainless steel chips was visualized using scanning electron microscopy, which revealed dense aggregates of cells held together by meshlike webbing.
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Affiliation(s)
- Andrew G Moltz
- Department of Food Science and Human Nutrition, University of Illinois, Urbana, Illinois 61801, USA
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