51
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Sahar A, Boubellouta T, Dufour É. Synchronous front-face fluorescence spectroscopy as a promising tool for the rapid determination of spoilage bacteria on chicken breast fillet. Food Res Int 2011. [DOI: 10.1016/j.foodres.2010.09.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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52
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Ellouze M, Augustin JC. Applicability of biological time temperature integrators as quality and safety indicators for meat products. Int J Food Microbiol 2010; 138:119-29. [DOI: 10.1016/j.ijfoodmicro.2009.12.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 12/04/2009] [Accepted: 12/09/2009] [Indexed: 10/20/2022]
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53
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Interception of quorum sensing signal molecule by furanone to enhance shelf life of fermented milk. Food Control 2010. [DOI: 10.1016/j.foodcont.2009.03.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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54
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Ferrocino I, Ercolini D, Villani F, Moorhead SM, Griffiths MW. Pseudomonas fragi strains isolated from meat do not produce N-acyl homoserine lactones as signal molecules. J Food Prot 2009; 72:2597-601. [PMID: 20003745 DOI: 10.4315/0362-028x-72.12.2597] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Quorum sensing (QS) is a signalling mechanism through which bacteria cellular functions are modified to promote access to nutrients and more favorable environmental niches. The frequent occurrence of Pseudomonas spp. in fresh and spoiled meat may involve enhanced gene expression regulated by QS. Several Pseudomonas spp. produce different N-acyl homoserine lactone (AHL) signal molecules. Meat spoilage during aerobic, refrigerated storage is often associated with the presence of Pseudomonas fragi. As with other Pseudomonas species in natural habitats, the dominance and activities of P. fragi in meat may be regulated by QS. In this study, five biosensor strains were used to detect AHL production on three different media by 72 different P. fragi strains isolated from fresh and spoiled meat. Positive and negative AHL-producing strains were used to verify the assays. None of the strains produced detectable quantities of AHLs, even when concentrated cell-free culture supernatants were assayed, nor did exogenous lactones increase biofilm formation in P. fragi strains. However, all isolates produced furanosyl borate diesters (type II autoinducers; AI-2) when tested using the bioluminescent biosensor strain of Vibrio harveyi (BB170). The production of AI-2 was presumed to be of metabolic origin even though Pseudomonas spp. have not been shown to harbor the luxS gene. Thus, the efficient development of P. fragi in fresh meat is not regulated by an AHL-mediated QS system. The mechanism of AI-2 production and its possible role in spoilage dynamics needs further study.
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Affiliation(s)
- Ilario Ferrocino
- Department of Food Science, School of Agriculture, University of Naples Federico II, 80055 Portici, Italy
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55
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Nychas GJ, Dourou D, Skandamis P, Koutsoumanis K, Baranyi J, Sofos J. Effect of microbial cell-free meat extract on the growth of spoilage bacteria. J Appl Microbiol 2009; 107:1819-29. [DOI: 10.1111/j.1365-2672.2009.04377.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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56
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Prendergast D, Crowley K, McDowell D, Sheridan J. Survival of Escherichia coli O157:H7 and non-pathogenic E. coli on irradiated and non-irradiated beef surfaces. Meat Sci 2009; 83:468-73. [DOI: 10.1016/j.meatsci.2009.06.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2009] [Revised: 05/22/2009] [Accepted: 06/15/2009] [Indexed: 10/20/2022]
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57
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Ercolini D, Ferrocino I, La Storia A, Mauriello G, Gigli S, Masi P, Villani F. Development of spoilage microbiota in beef stored in nisin activated packaging. Food Microbiol 2009; 27:137-43. [PMID: 19913704 DOI: 10.1016/j.fm.2009.09.006] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 09/10/2009] [Accepted: 09/11/2009] [Indexed: 10/20/2022]
Abstract
The aim of this study was to assess the microbial populations causing the spoilage of chilled beef during storage and to evaluate the effect of the use of an antimicrobial packaging for the meat storage. A nisin activated antimicrobial packaging was developed by using a nisin, HCL and EDTA solution and used for the storage of beef cuts at 1 degrees C. The common spoilage related microbial groups were monitored during the storage of beef in activated and non activated plastic bags by using selective media. The use of the antimicrobial packaging caused an overall significant reduction of viable counts of Gram positive bacteria such as carnobacteria, lactic acid bacteria and Brochotrix thermosphacta whose development was inhibited for at least 11 days of storage compared to the control. Moreover, a 1-3 log cycles reduction of enterobacteria was also registered between 22 and 32 days of storage. The microbiota was assessed at species level by using Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis of 16S rRNA gene of DNA extracted directly from meat and from bulk cells from selective media plates and showed that the species occurring within the targeted microbial groups did not change according to storage conditions. In conclusion, the use of the nisin activated packaging reduced the number of spoilage populations but did not affect the species diversity. Improved antimicrobial packaging is needed, possibly coupled with vacuum storage, to possibly achieve a simultaneous inhibition of more spoilage microbial groups and to preserve the microbiological quality of beef during chilled storage.
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Affiliation(s)
- Danilo Ercolini
- Department of Food Science, The University of Naples Federico II, via Università 100, 80055 Portici, Italy
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58
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Ercolini D, Russo F, Nasi A, Ferranti P, Villani F. Mesophilic and psychrotrophic bacteria from meat and their spoilage potential in vitro and in beef. Appl Environ Microbiol 2009; 75:1990-2001. [PMID: 19201980 PMCID: PMC2663181 DOI: 10.1128/aem.02762-08] [Citation(s) in RCA: 230] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 01/25/2009] [Indexed: 11/20/2022] Open
Abstract
Mesophilic and psychrotrophic populations from refrigerated meat were identified in this study, and the spoilage potential of microbial isolates in packaged beef was evaluated by analyzing the release of volatile organic compounds (VOC) by gas chromatography-mass spectrometry (GC/MS). Fifty mesophilic and twenty-nine psychrotrophic isolates were analyzed by random amplified polymorphic DNA-PCR, and representative strains were identified by 16S rRNA gene sequencing. Carnobacterium maltaromaticum and C. divergens were the species most frequently found in both mesophilic and psychrotrophic populations. Acinetobacter baumannii, Buttiauxella spp. and Serratia spp. were identified among the mesophilic isolates, while Pseudomonas spp. were commonly identified among the psychrotrophs. The isolates were further characterized for their growth at different temperatures and their proteolytic activity in vitro on meat proteins extracts at 7 degrees C. Selected proteolytic strains of Serratia proteamaculans, Pseudomonas fragi, and C. maltaromaticum were used to examine their spoilage potential in situ. Single strains of these species and mixtures of these strains were used to contaminate beef chops that were packed and stored at 7 degrees C. At time intervals up to 1 month, viable counts were determined, and VOC were identified by GC/MS. Generally, the VOC concentrations went to increase during the storage of the contaminated meats, and the profiles of the analyzed meat changed dramatically depending on the contaminating microbial species. About 100 volatiles were identified in the different contaminated samples. Among the detected volatiles, some specific molecules were identified only when the meat was contaminated by a specific microbial species. Compounds such as 2-ethyl-1-hexanol, 2-buten-1-ol, 2-hexyl-1-octanol, 2-nonanone, and 2-ethylhexanal were detectable only for C. maltaromaticum, which also produced the highest number of aldehydes, lactones, and sulfur compounds. The highest number of alcohols and ketons were detected in the headspace of meat samples contaminated by P. fragi, whereas the highest concentrations of some alcohols, such as 1-octen-3-ol, and some esters, such as isoamyl acetate, were produced by S. proteamaculans. In conclusion, different microbial species can contribute to meat spoilage with release of different volatile compounds that concur to the overall quality decrease of spoiling meat.
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Affiliation(s)
- Danilo Ercolini
- Department of Food Science, School of Biotechnological Sciences, University of Naples Federico II, Via Università 100, 80055 Portici, Italy
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59
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YOON Y, SOFOS J. CONDITIONS AFFECTING AUTOINDUCER-2-BASED QUORUM-SENSING OF ESCHERICHIA COLI O157:H7 ON FRESH BEEF. J Food Saf 2008. [DOI: 10.1111/j.1745-4565.2008.00133.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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60
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Gori K, Mortensen HD, Arneborg N, Jespersen L. Ammonia production and its possible role as a mediator of communication for Debaryomyces hansenii and other cheese-relevant yeast species. J Dairy Sci 2008; 90:5032-41. [PMID: 17954742 DOI: 10.3168/jds.2006-750] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ammonia production by yeasts may contribute to an increase in pH during the ripening of surface-ripened cheeses. The increase in pH has a stimulatory effect on the growth of secondary bacterial flora. Ammonia production of single colonies of Debaryomyces hansenii, Saccharomyces cerevisiae, Yarrowia lipolytica, and Geotrichum candidum was determined on glycerol medium (GM) agar and cheese agar. The ammonia production was found to vary, especially among yeast species, but also within strains of D. hansenii. In addition, variations in ammonia production were found between GM agar and cheese agar. Ammonia production was positively correlated to pH measured around colonies, which suggests ammonia production as an additional technological parameter for selection of secondary starter cultures for cheese ripening. Furthermore, ammonia appeared to act as a signaling molecule in D. hansenii as reported for other yeasts. On GM agar and cheese agar, D. hansenii showed ammonia production oriented toward neighboring colonies when colonies were grown close to other colonies of the same species; however, the time to oriented ammonia production differed among strains and media. In addition, an increase of ammonia production was determined for double colonies compared with single colonies of D. hansenii on GM agar. In general, similar levels of ammonia production were determined for both single and double colonies of D. hansenii on cheese agar.
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Affiliation(s)
- K Gori
- Department of Food Science, Food Microbiology, The Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
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61
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Ammor MS, Michaelidis C, Nychas GJE. Insights into the role of quorum sensing in food spoilage. J Food Prot 2008; 71:1510-25. [PMID: 18680957 DOI: 10.4315/0362-028x-71.7.1510] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Food spoilage is a consequence of the degrading enzymatic activity of some food-associated bacteria. Several proteolytic, lipolytic, chitinolytic, and pectinolytic activities associated with the deterioration of goods are regulated by quorum sensing, suggesting a potential role of such cell-to-cell communication in food spoilage. Here we review quorum sensing signaling molecules and methods of their detection and quantification, and we provide insights into the role of quorum sensing in food spoilage and address potential quorum sensing inhibitors that might be used as biopreservatives.
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Affiliation(s)
- Mohammed Salim Ammor
- Laboratory of Microbiology and Biotechnology of Foods, Department of Food Science & Technology, Agricultural University of Athens, 75 lera Odos, 11855 Athens, Greece.
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62
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Ghafir Y, China B, Dierick K, De Zutter L, Daube G. Hygiene indicator microorganisms for selected pathogens on beef, pork, and poultry meats in Belgium. J Food Prot 2008; 71:35-45. [PMID: 18236660 DOI: 10.4315/0362-028x-71.1.35] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Several bacterial indicators are used to evaluate hygiene during the meat slaughtering process. The objectives of this study were to assess the Belgian baseline data on hygienic indicators and the relationship between the indicators and zoonotic agents to establish hygiene indicator criteria for cattle, pig, and chicken carcasses and meat. The study used the results from the official Belgian surveillance plan from 2000 to 2003, which included the monitoring of Escherichia coli counts (ECC), Enterobacteriaceae counts (EC), aerobic colony counts (ACC), and Pseudomonas counts (PC). The sampling method was the wet and dry swabbing technique for cattle and pig carcasses and neck skin excision for broiler and layer chicken carcasses. The 75th and 95th percentiles of ECC were -0.20 and 0.95 log CFU/cm2 for cattle carcasses, 1.20 and 2.32 log CFU/cm2 for pig carcasses, and 4.05 and 5.24 log CFU/g for chicken carcasses. The ACC were 2.1- to 4.5-log higher than the ECC for cattle, pigs, and chickens. For cattle and pig carcasses, a significant correlation between ECC, EC, and ACC was found. ECC for pork and beef samples and EC in pig carcasses were significantly higher in samples contaminated with Salmonella. In poultry samples, ECC were in general higher for samples containing Salmonella or Campylobacter. Thus, E. coli may be considered as a good indicator for enteric zoonotic agents such as Salmonella for beef, pork, and poultry samples and for Campylobacter in poultry samples.
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Affiliation(s)
- Y Ghafir
- Belgian National Reference Laboratory in Food Microbiology for the Federal Agency for the Safety of the Food Chain, Brussels, Belgium.
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63
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Dominguez SA, Schaffner DW. Development and validation of a mathematical model to describe the growth of Pseudomonas spp. in raw poultry stored under aerobic conditions. Int J Food Microbiol 2007; 120:287-95. [DOI: 10.1016/j.ijfoodmicro.2007.09.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 09/05/2007] [Accepted: 09/19/2007] [Indexed: 11/25/2022]
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64
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Pinto UM, de Souza Viana E, Martins ML, Vanetti MCD. Detection of acylated homoserine lactones in gram-negative proteolytic psychrotrophic bacteria isolated from cooled raw milk. Food Control 2007. [DOI: 10.1016/j.foodcont.2006.09.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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65
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Liu M, Wang H, Griffiths M. Regulation of alkaline metalloprotease promoter by N-acyl homoserine lactone quorum sensing in Pseudomonas fluorescens. J Appl Microbiol 2007; 103:2174-84. [DOI: 10.1111/j.1365-2672.2007.03488.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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66
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Gobbetti M, De Angelis M, Di Cagno R, Minervini F, Limitone A. Cell-cell communication in food related bacteria. Int J Food Microbiol 2007; 120:34-45. [PMID: 17617483 DOI: 10.1016/j.ijfoodmicro.2007.06.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Revised: 02/07/2007] [Indexed: 11/26/2022]
Abstract
Although the study of quorum sensing is relatively recent, it has been well established that bacteria produce, release, detect and respond to small signalling hormone-like molecules called "autoinducers". When a critical threshold concentration of the signal molecule is achieved, bacteria detect its presence and initiate a signalling cascade resulting in changes of target gene expression. Cell-cell communication has been shown within and between species with mechanisms substantially different in Gram-positive and Gram-negative bacteria. The identified quorum-sensing mechanisms in several food related Gram-negative and Gram-positive bacteria, including bacteriocin synthesis, luxS quorum sensing and interactions between sourdough starter lactic acid bacteria are reviewed. The understanding of extracellular signalling may provide a new basis for controlling over molecular and cellular process the deleterious and useful food related bacteria whose behaviour is mostly a consequence of very complex community interactions.
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Affiliation(s)
- M Gobbetti
- Dipartimento di Protezione delle Piante e Microbiologia Applicata, Università degli Studi di Bari, Bari, Italy.
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67
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Liu M, Gray JM, Griffiths MW. Occurrence of proteolytic activity and N-acyl-homoserine lactone signals in the spoilage of aerobically chill-stored proteinaceous raw foods. J Food Prot 2006; 69:2729-37. [PMID: 17133818 DOI: 10.4315/0362-028x-69.11.2729] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Proteolytic pseudomonads dominate the spoilage flora of aerobically chill-stored proteinaceous raw foods. Proteolysis during spoilage of these food systems affects both food quality and the dynamics of the bacterial community because it increases the availability of nutrients to the community as a whole. Quorum sensing, or cell-cell signaling, is associated closely with ecological interactions among bacteria in mixed communities. The potential role of quorum sensing in proteolytic food spoilage was examined, based on the evaluation of N-acyl-homoserine lactone (AHL) signal molecules. The occurrence of proteolytic activity and AHL signals was studied during spoilage of aerobically chill-stored ground beef, fish, chicken, and raw milk. Pseudomonads dominated the psychrotrophic flora, followed distantly by members of the Enterobacteriaceae. The growth of pseudomonads was correlated with the occurrence of proteolytic activity in all food systems. AHL concentration began increasing significantly only after the onset of proteolytic activity. Widely divergent AHL profiles were revealed by thin-layer chromatography analysis of the different food samples, and these profiles were likely determined by the undefined bacterial flora in these systems and by the characterized pseudomonads and Enterobacteriaceae. Although Hafnia alvei was a major component of the Enterobacteriaceae flora in all foods tested and a strong AHL producer, the signal molecules produced by H. alvei strain EB1 did not influence protease production by Pseudomonas fluorescens strain 395 in vitro. These results do not indicate any clear correlation between the overall detectable AHL signal molecules accumulated in the food samples and proteolytic activity.
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Affiliation(s)
- M Liu
- Canadian Research Institute for Food Safety, Department of Food Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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68
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Li MY, Zhou GH, Xu XL, Li CB, Zhu WY. Changes of bacterial diversity and main flora in chilled pork during storage using PCR-DGGE. Food Microbiol 2006; 23:607-11. [PMID: 16943058 DOI: 10.1016/j.fm.2006.01.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2005] [Revised: 01/23/2006] [Accepted: 01/23/2006] [Indexed: 10/24/2022]
Abstract
This study was designed to explore the bacterial diversity and the main flora in chilled pork by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Longissimus muscle was removed from pork carcasses at 24 h postmortem. The muscle was tray- and vacuum-packaged at 4 degrees C for 2, 4, 7 days to extract the bacteria total DNA, respectively. The results indicated that the bacterial diversity of chilled pork decreased with storage time regardless of packaging method. Nine types of bacteria were identified, including Arthrobacter sp., Enterococcus sp., Staphylococcus sp., Moraxella sp., Pseudomonas sp., Lactobacillus sp., Aeromonas sp., Acinetobacter sp., Brochothrix thermosphacta. For tray-packaged pork, Pseudomonas sp. and B. thermosphacta were the dominant micro-organisms. The differences in the species found were related with the presence of Lactobacillus sp. in vacuum-packaged meat. The results of the present study might be useful to study the changes of the contaminating bacteria and their characteristics in chilled pork.
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Affiliation(s)
- M Y Li
- Key Lab of Meat Processing and Quality Control, MOE, Key Lab of Agricultural and Animal Products Processing and Quality Control, MOA, College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China
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69
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Medina-Martínez MS, Uyttendaele M, Demolder V, Debevere J. Effect of temperature and glucose concentration on the N-butanoyl-l-homoserine lactone production by Aeromonas hydrophila. Food Microbiol 2006; 23:534-40. [PMID: 16943048 DOI: 10.1016/j.fm.2005.09.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Revised: 09/23/2005] [Accepted: 09/23/2005] [Indexed: 10/25/2022]
Abstract
N-butanoyl-L-homoserine lactone (C4-HSL) production by Aeromonas hydrophila 519 has been established. C4-HSL production at 22 and 30 degrees C was found after 20-24 h of incubation corresponding to a population density of ca. 10(8)-10(9) cfu/ml, respectively. Reduced C4-HSL production was noted after 72 h of incubation at 12 degrees C when the culture reached ca. 10(9) cfu/ml. No C4-HSL production was detected at 37 degrees C, although a dense population was obtained. In LB broth supplemented with 0.1% and 0.5% glucose, C4-HSL production was noted whereas with 1% glucose no C4-HSL was detected although a high colony count was obtained. In the latter culture residual levels of glucose (0.65%) were found after 43 h whereas in the 0.1% and 0.5% supplemented LB, glucose was quickly consumed which may have stimulated C4-HSL production. In conclusion, the present study shows an effect of environmental conditions (temperature, glucose concentration) on the C4-HSL production and warrants further investigation to elucidate the effect of external conditions on production of AHL signal molecules to reveal the relevance of quorum sensing in, e.g. foods.
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Affiliation(s)
- M S Medina-Martínez
- Laboratory of Food Microbiology and Food Preservation, Faculty of BioScience Engineering, Ghent University, UGent, Coupure Links, 653-9000 Ghent, Belgium
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70
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Ercolini D, Russo F, Torrieri E, Masi P, Villani F. Changes in the spoilage-related microbiota of beef during refrigerated storage under different packaging conditions. Appl Environ Microbiol 2006; 72:4663-71. [PMID: 16820458 PMCID: PMC1489361 DOI: 10.1128/aem.00468-06] [Citation(s) in RCA: 278] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2006] [Accepted: 04/20/2006] [Indexed: 11/20/2022] Open
Abstract
The microbial spoilage of beef was monitored during storage at 5 degrees C under three different conditions of modified-atmosphere packaging (MAP): (i) air (MAP1), (ii) 60% O2 and 40% CO2 (MAP2), and (iii) 20% O2 and 40% CO2 (MAP3). Pseudomonas, Enterobacteriaceae, Brochothrix thermosphacta, and lactic acid bacteria were monitored by viable counts and PCR-denaturing gradient gel electrophoresis (DGGE) analysis during 14 days of storage. Moreover, headspace gas composition, weight loss, and beef color change were also determined at each sampling time. Overall, MAP2 was shown to have the best protective effect, keeping the microbial loads and color change to acceptable levels in the first 7 days of refrigerated storage. The microbial colonies from the plate counts of each microbial group were identified by PCR-DGGE of the variable V6-V8 region of the 16S rRNA gene. Thirteen different genera and at least 17 different species were identified after sequencing of DGGE fragments that showed a wide diversity of spoilage-related bacteria taking turns during beef storage in the function of the packaging conditions. The countable species for each spoilage-related microbial group were different according to packaging conditions and times of storage. In fact, the DGGE profiles displayed significant changes during time and depending on the initial atmosphere used. The spoilage occurred between 7 and 14 days of storage, and the microbial species found in the spoiled meat varied according to the packaging conditions. Rahnella aquatilis, Rahnella spp., Pseudomonas spp., and Carnobacterium divergens were identified as acting during beef storage in air (MAP1). Pseudomonas spp. and Lactobacillus sakei were found in beef stored under MAP conditions with high oxygen content (MAP2), while Rahnella spp. and L. sakei were the main species found during storage using MAP3. The identification of the spoilage-related microbiota by molecular methods can help in the effective establishment of storage conditions for fresh meat.
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Affiliation(s)
- Danilo Ercolini
- Dipartimento di Scienza degli Alimenti, Università degli Studi di Napoli Federico II, via Università 100, 80055 Portici (NA), Italy
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71
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Guo Q, Piyasena P, Mittal GS, Si W, Gong J. Efficacy of radio frequency cooking in the reduction of Escherichia coli and shelf stability of ground beef. Food Microbiol 2006; 23:112-8. [PMID: 16942994 DOI: 10.1016/j.fm.2005.02.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2004] [Revised: 02/21/2005] [Accepted: 02/21/2005] [Indexed: 11/30/2022]
Abstract
The effectiveness of radio frequency (RF) cooking on the inactivation of Escherichia coli in ground beef and its effect on the shelf stability of ground beef were investigated with a comparison to hot water-bath cooking. E. coli K12 was used as a target bacterium instead of E. coli O157:H7. The ground beef samples inoculated with E. coli K12 (ampr) were heated until the centre temperature of each sample reached 72 degrees C. These samples were then stored at 4 degrees C for up to 30 days. The enumeration of E. coli K12, background E. coli and coliform counts in ground beef samples was carried out for shelf-life study. Although both methods significantly reduced E. coli K12 (ampr), E. coli and coliform counts and extended the shelf-life, RF cooking had a shorter cooking time, and more uniform heating. Thus, RF cooking of meat has a high potential as a substitute for the hot water-bath cooking.
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Affiliation(s)
- Q Guo
- School of Engineering, University of Guelph, Guelph, Ont., Canada N1G 2W1
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72
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Abstract
Only a decade ago, the secretion and perception of small signalling molecules that in turn are transduced to coordinate behaviour of a 'minimal unit' of microorganisms was termed quorum sensing by EP Greenberg and colleagues. Since then, an explosion (or exponential growth) in understanding and prevalence of quorum-sensing systems has ensued, with sightings ranging from virulence in human and plant pathogens to degradative capacity of activated sludge. Not surprisingly, regulatory mechanisms span traditional inducer/repressor motifs homologous to the lac operon to the recently discovered interfering RNAs. Further characterisation of signalling circuits, coupled with creative niche applications, suggest a wealth of opportunity for advancing commercial biotechnology.
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Affiliation(s)
- John C March
- Center for Biosystems Research, University of Maryland Biotechnology Institute, 5115 Plant Sciences Building, College Park 20742, USA
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73
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Bruhn JB, Christensen AB, Flodgaard LR, Nielsen KF, Larsen TO, Givskov M, Gram L. Presence of acylated homoserine lactones (AHLs) and AHL-producing bacteria in meat and potential role of AHL in spoilage of meat. Appl Environ Microbiol 2004; 70:4293-302. [PMID: 15240313 PMCID: PMC444785 DOI: 10.1128/aem.70.7.4293-4302.2004] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Quorum-sensing (QS) signals (N-acyl homoserine lactones [AHLs]) were extracted and detected from five commercially produced vacuum-packed meat samples. Ninety-six AHL-producing bacteria were isolated, and 92 were identified as Enterobacteriaceae. Hafnia alvei was the most commonly identified AHL-producing bacterium. Thin-layer chromatographic profiles of supernatants from six H. alvei isolates and of extracts from spoiling meat revealed that the major AHL species had an R(f) value and shape similar to N-3-oxo-hexanoyl homoserine lactone (OHHL). Liquid chromatography-mass spectrometry (MS) (high-resolution MS) analysis confirmed the presence of OHHL in pure cultures of H. alvei. Vacuum-packed meat spoiled at the same rate when inoculated with the H. alvei wild type compared to a corresponding AHL-lacking mutant. Addition of specific QS inhibitors to the AHL-producing H. alvei inoculated in meat or to naturally contaminated meat did not influence the spoilage of vacuum-packed meat. An extracellular protein of approximately 20 kDa produced by the H. alvei wild-type was not produced by the AHL-negative mutant but was restored in the mutant when complemented by OHHL, thus indicating that AHLs do have a regulatory role in H. alvei. Coinoculation of H. alvei wild-type with an AHL-deficient Serratia proteamaculans B5a, in which protease secretion is QS regulated, caused spoilage of liquid milk. By contrast, coinoculation of AHL-negative strains of H. alvei and S. proteamaculans B5a did not cause spoilage. In conclusion, AHL and AHL-producing bacteria are present in vacuum-packed meat during storage and spoilage, but AHL does not appear to influence the spoilage of this particular type of conserved meat. Our data indicate that AHL-producing H. alvei may induce food quality-relevant phenotypes in other bacterial species in the same environment. H. alvei may thus influence spoilage of food products in which Enterobacteriaceae participate in the spoilage process.
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Affiliation(s)
- Jesper Bartholin Bruhn
- Danish Institute for Fisheries Research, Department of Seafood Research, Søltofts Plads, c/o Technical University of Denmark bldg. 221, DK-2800 Kgs. Lyngby, Denmark.
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74
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Lu L, Hume ME, Pillai SD. Autoinducer-2-like activity associated with foods and its interaction with food additives. J Food Prot 2004; 67:1457-62. [PMID: 15270501 DOI: 10.4315/0362-028x-67.7.1457] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The autoinducer-2 (AI-2) molecule produced by bacteria as part of quorum sensing is considered to be a universal inducer signal in bacteria because it reportedly influences gene expression in a variety of both gram-negative and gram-positive bacteria. The objective of this study was to determine whether selected fresh produce and processed foods have AI-2-like activity and whether specific food additives can act as AI-2 mimics and result in AI-2-like activity. The luminescence-based response of the reporter strain Vibrio harveyi BB170 was used as the basis for determining AI-2 activity in the selected foods and food ingredients. Maximum AI-2 activity was seen on the frozen fish sample (203-fold, compared with the negative control) followed by tomato, cantaloupe, carrots, tofu, and milk samples. Interestingly, some samples were capable of inhibiting AI-2 activity. Turkey patties showed the highest inhibition (99.8% compared with the positive control) followed by chicken breast (97.5%), homemade cheeses (93.7%), beef steak (90.6%), and beef patties (84.4%). AI-2 activity was almost totally inhibited by sodium propionate, whereas sodium benzoate caused 93.3% inhibition, compared with 75% inhibition by sodium acetate. Sodium nitrate did not have any appreciable effect, even at 200 ppm. Understanding the relationships that exist between AI-2 activity on foods and the ecology of pathogens and food spoilage bacteria on foods could yield clues about factors controlling food spoilage and pathogen virulence.
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Affiliation(s)
- Lingeng Lu
- Poultry Science Department and Institute of Food Science and Engineering, Food Safety and Environmental Microbiology Program, Texas A&M University, College Station, Texas 77843, USA
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Abstract
Quorum sensing is a signaling mechanism through which bacteria modulate a number of cellular functions (genes), including sporulation, biofilm formation, bacteriocin production, virulence responses, as well as others. Quorum sensing is a mechanism of cell-to-cell communication and is mediated by extracellular chemical signals generated by the bacteria when specific cell densities are reached. When the concentration of the signal (and cell population) is sufficiently high, the target gene or genes are either activated or repressed. Quorum sensing increases the ability of the bacteria to have access to nutrients or to more favorable environmental niches and enhances bacterial defenses against eukaryotic hosts, competing bacteria, and environmental stresses. The physiological and clinical aspects of quorum sensing have received considerable attention and have been studied at the molecular level. Little is known, however, on the role of quorum sensing in food spoilage or in the growth and/or toxin production of pathogens present in food. A number of compounds have been isolated or synthesized that antagonize quorum sensors, and application of these antagonists may potentially be useful in inhibiting the growth or virulence mechanisms of bacteria in different environments, including food. It is important that food microbiologists have an awareness and an understanding of the mechanisms involved in bacterial quorum sensing, since strategies targeting quorum sensing may offer a means to control the growth of undesirable bacteria in foods.
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Affiliation(s)
- James L Smith
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
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