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Effects of Modified Atmosphere Packaging with Various CO2 Concentrations on the Bacterial Community and Shelf-Life of Smoked Chicken Legs. Foods 2022; 11:foods11040559. [PMID: 35206036 PMCID: PMC8870794 DOI: 10.3390/foods11040559] [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: 01/20/2022] [Revised: 02/06/2022] [Accepted: 02/14/2022] [Indexed: 12/04/2022] Open
Abstract
The effects of modified atmosphere packaging (MAP) with various CO2 concentrations on the bacterial community and shelf-life of smoked chicken legs during 25 d of storage at 4 °C were evaluated herein. Four treatments were stored in pallets (PAL) and MAP under 20% (M20), 60% (M60), and 100% (M100) CO2, respectively. The results indicated that the MAP treatments provided the legs with higher redness and hardness and lower yellowness, luminance, and lipid oxidation, compared with the PAL treatment. In addition, the MAP treatments effectively inhibited the growth of viable bacteria, delayed bacterial spoilage, and extended the shelf-life of the samples. The M60 and M100 treatments had a better inhibition effect on bacteria. In terms of bacterial community, Carnobacterium, Pseudomonas, Brochothrix, and Lactococcus were the most predominant genera in the 25 d-stored MAP samples, with Carnobacterium maltaromaticum, Pseudomonas fragi, Shewanella baltica, and Lactococcus piscium being the dominant species. However, while the inhibition effects of the M60 and M100 treatments on the bacterial community at Day 25 were similar, the outer package of the M100 treatment collapsed. Overall, the M60 treatment may be a promising approach to improving the quality and extending the shelf-life of smoked chicken legs.
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Quintieri L, Caputo L, Brasca M, Fanelli F. Recent Advances in the Mechanisms and Regulation of QS in Dairy Spoilage by Pseudomonas spp. Foods 2021; 10:foods10123088. [PMID: 34945641 PMCID: PMC8701193 DOI: 10.3390/foods10123088] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 11/28/2021] [Accepted: 12/08/2021] [Indexed: 11/16/2022] Open
Abstract
Food spoilage is a serious issue dramatically impacting the worldwide need to counteract food insecurity. Despite the very expensive application of low temperatures, the proper conservation of fresh dairy products is continuously threatened at different stages of production and commercialization by psychrotrophic populations mainly belonging to the Pseudomonas genus. These bacteria cause discolouration, loss of structure, and off-flavours, with fatal implications on the quality and shelf-life of products. While the effects of pseudomonad decay have been widely reported, the mechanisms responsible for the activation and regulation of spoilage pathways are still poorly explored. Recently, molecule signals and regulators involved in quorum sensing (QS), such as homoserine lactones, the luxR/luxI system, hdtS, and psoR, have been detected in spoiled products and bacterial spoiler species; this evidence suggests the role of bacterial cross talk in dairy spoilage and paves the way towards the search for novel preservation strategies based on QS inhibition. The aim of this review was to investigate the advancements achieved by the application of omic approaches in deciphering the molecular mechanisms controlled by QS systems in pseudomonads, by focusing on the regulators and metabolic pathways responsible for spoilage of fresh dairy products. In addition, due the ability of pseudomonads to quickly spread in the environment as biofilm communities, which may also include pathogenic and multidrug-resistant (MDR) species, the risk derived from the gaps in clearly defined and regulated sanitization actions is underlined.
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Affiliation(s)
- Laura Quintieri
- Institute of Sciences of Food Production, National Research Council of Italy, 70126 Bari, Italy; (L.C.); (F.F.)
- Correspondence: author:
| | - Leonardo Caputo
- Institute of Sciences of Food Production, National Research Council of Italy, 70126 Bari, Italy; (L.C.); (F.F.)
| | - Milena Brasca
- Institute of Sciences of Food Production, National Research Council of Italy, 20133 Milan, Italy;
| | - Francesca Fanelli
- Institute of Sciences of Food Production, National Research Council of Italy, 70126 Bari, Italy; (L.C.); (F.F.)
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Transcriptional profiling of biofilms formed on chilled beef by psychrotrophic meat spoilage bacterium, Pseudomonas fragi 1793. Biofilm 2021; 3:100045. [PMID: 33718862 PMCID: PMC7921472 DOI: 10.1016/j.bioflm.2021.100045] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 01/26/2021] [Accepted: 02/02/2021] [Indexed: 11/21/2022] Open
Abstract
Pseudomonas fragi is the predominant bacterial species associated with spoiled aerobically stored chilled meat worldwide. It readily forms biofilms on meat under refrigerated temperature conditions used in the meat industry. Biofilm growth leads to slime development on meat which in turn becomes a major quality defect. To understand the genetic regulation that aids P. fragi to survive under chilled conditions used in the meat industry, as well to obtain an overview of the transcriptomic behavior of this organism when grown as biofilms, RNA sequencing was carried out for the main stages of the P. fragi 1793 biofilm. RNA was extracted at different stages of the biofilm cycle namely initiation, maturation and dispersal. At the same time, the biofilm growth was assessed by fluorescent staining and imaging using confocal laser scanning microscope. The results of RNA sequencing were verified by qRT-PCR using twelve genes that were most significantly up and down regulated at each stage. Differential expression analysis at biofilm maturation revealed 332 significantly upregulated genes and 37 downregulated genes relative to initiation. Differential expression analysis at biofilm dispersal reveled 658 upregulated and 275 downregulated genes relative to initiation. During biofilm maturation and dispersal, genes coding for flp family type IVb pilin, ribosome modulation factor, creatininase were the most upregulated genes while genes encoding for iron uptake systems including TonB-dependent siderophore receptor and taurine transport were significantly down regulated. The results show that protein synthesis and cellular multiplication cease after the biofilm population maximum has reached.
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Wickramasinghe NN, Hlaing MM, Ravensdale JT, Coorey R, Chandry PS, Dykes GA. Characterization of the biofilm matrix composition of psychrotrophic, meat spoilage pseudomonads. Sci Rep 2020; 10:16457. [PMID: 33020559 PMCID: PMC7536239 DOI: 10.1038/s41598-020-73612-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 09/11/2020] [Indexed: 02/02/2023] Open
Abstract
Psychrotrophic Pseudomonas species are the key spoilage bacteria of aerobically stored chilled meat. These organisms readily form biofilms on meat under refrigerated conditions leading to consumer rejection and associated economic losses. Limited information is available on the matrix composition of the biofilms formed by these bacteria. We quantified and characterized the main components of the matrix of mono-species biofilms of selected Pseudomonas fragi and Pseudomonas lundensis strains using chemical analysis and Raman spectroscopy. The biofilms were grown at 10 °C and 25 °C on nitro-cellulose membranes placed on surface sterilized beef cuts. Extra-cellular polymeric substances of the matrix were extracted in soluble and bound forms and were chemically assessed for total carbohydrates, proteins and extra-cellular DNA. Both Pseudomonas species showed a significant increase in total carbohydrates and total proteins when grown at 10 °C as compared to 25 °C. Extra-cellular DNA did not show a strong correlation with growth temperature. Raman spectra were obtained from planktonic bacteria and membrane grown biofilms at 10 °C and 25 °C. Higher levels of guanine were detected in planktonic cells as compared to biofilm cells. This study suggests that psychrotrophic Pseudomonas species may respond to cold stress by increasing extra-cellular polymer secretions.
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Affiliation(s)
- Nirmani N Wickramasinghe
- School of Public Health, Curtin University, Bentley, WA, 6102, Australia
- CSIRO, Agriculture and Food, Werribee, VIC, 3030, Australia
| | - Mya M Hlaing
- CSIRO, Agriculture and Food, Werribee, VIC, 3030, Australia
| | | | - Ranil Coorey
- School of Molecular and Life Sciences, Curtin University, Bentley, WA, 6102, Australia
| | | | - Gary A Dykes
- Graduate Research School, Curtin University, Bentley, WA, 6102, Australia.
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5
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Wickramasinghe NN, Ravensdale JT, Coorey R, Dykes GA, Scott Chandry P. In situ characterisation of biofilms formed by psychrotrophic meat spoilage pseudomonads. BIOFOULING 2019; 35:840-855. [PMID: 31558055 DOI: 10.1080/08927014.2019.1669021] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Psychrotrophic Pseudomonas species form biofilms on meat during refrigerated and temperature abuse conditions. Biofilm growth leads to slime formation on meat which is a key organoleptic degradation characteristic. Limited research has been undertaken characterising biofilms grown on meat during chilled aerobic storage. In this work, biofilms formed by two key meat spoilage organisms, Pseudomonas fragi and Pseudomonas lundensis were studied in situ using five strains from each species. Biofilm structures were studied using confocal microscope images, cellular arrangement, cell counts and biomass quantifications. This work demonstrated that highly dense, compact biofilms are a characteristic of P. fragi strains. P. lundensis formed biofilms with loosely arranged cells. The cells in P. fragi biofilm appear to be vertically oriented whereas this characteristic was absent in P. lundensis biofilms formed under identical conditions. Despite the continued access to nutrients, biofilms formed on meat by proteolytic Pseudomonas species dispersed after a population maximum was reached.
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Affiliation(s)
- Nirmani N Wickramasinghe
- School of Public Health, Curtin University, Bentley, Western Australia, Australia
- Agriculture and Food, CSIRO, Werribee, Victoria, Australia
| | - Joshua T Ravensdale
- School of Public Health, Curtin University, Bentley, Western Australia, Australia
| | - Ranil Coorey
- School of Molecular and Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Gary A Dykes
- School of Public Health, Curtin University, Bentley, Western Australia, Australia
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Wickramasinghe NN, Ravensdale J, Coorey R, Chandry SP, Dykes GA. The Predominance of Psychrotrophic Pseudomonads on Aerobically Stored Chilled Red Meat. Compr Rev Food Sci Food Saf 2019; 18:1622-1635. [DOI: 10.1111/1541-4337.12483] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/27/2019] [Accepted: 07/02/2019] [Indexed: 01/05/2023]
Affiliation(s)
- Nirmani N. Wickramasinghe
- School of Public HealthCurtin Univ. Perth Western Australia 6845 Australia
- Dept. of Agriculture and FoodCSIRO Werribee Victoria 3030 Australia
| | - Joshua Ravensdale
- School of Public HealthCurtin Univ. Perth Western Australia 6845 Australia
| | - Ranil Coorey
- School of Molecular an Health SciencesCurtin Univ. Perth Western Australia 6845 Australia
| | - Scott P. Chandry
- Dept. of Agriculture and FoodCSIRO Werribee Victoria 3030 Australia
| | - Gary A. Dykes
- School of Public HealthCurtin Univ. Perth Western Australia 6845 Australia
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Nahar S, Mizan MFR, Ha AJW, Ha SD. Advances and Future Prospects of Enzyme-Based Biofilm Prevention Approaches in the Food Industry. Compr Rev Food Sci Food Saf 2018; 17:1484-1502. [DOI: 10.1111/1541-4337.12382] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/22/2018] [Accepted: 06/27/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Shamsun Nahar
- Dept. of Food Science and Technology; Chung-Ang Univ.; Anseong Gyeonggi-Do 456-756 Republic of Korea
| | | | - Angela Jie-won Ha
- Dept. of Food Science and Technology; Chung-Ang Univ.; Anseong Gyeonggi-Do 456-756 Republic of Korea
| | - Sang-Do Ha
- Dept. of Food Science and Technology; Chung-Ang Univ.; Anseong Gyeonggi-Do 456-756 Republic of Korea
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Gopu V, Shetty PH. Regulation of acylated homoserine lactones (AHLs) in beef by spice marination. Journal of Food Science and Technology 2016; 53:2686-94. [PMID: 27478224 DOI: 10.1007/s13197-016-2240-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 04/25/2016] [Accepted: 04/27/2016] [Indexed: 11/26/2022]
Abstract
Quorum sensing (QS) is a signaling mechanism used by bacteria to communicate each other through the release of auto-inducing signaling molecules. Despite the fact that bacteria regulate its phenotypes by QS mechanism, their potential role in meat spoilage is not yet elucidated. In the current study, beef samples were analyzed for its microbial association and for the presence of N-acyl-homoserine-lactone (AHLs) throughout the storage experiments. Isolates were screened for AHLs production and selected spices were screened for their quorum sensing inhibitory (QSI) activity. In addition, effect of spices on AHLs production of Y. enterocolitica was quantified through high performance thin layer chromatography (HP-TLC). Outcome showed that microbial association of beef mainly consists of lactic acid bacteria (LAB) and Enterobacteriaceae. Samples stored at both aerobic and modified atmospheric packaging (MAP) exhibited higher counts whereas; marinated samples stored at MAP exhibited the lowest. It was found that out of 35 isolates Y. enterocolitica induced reporter strain CV026 and its cell-free supernatant contained 26.36 nM/100 ml of AHLs when compared to standard. Among the tested spices, C. cyminum exhibited pronounced results by significantly reducing the AHLs concentration up to 47.75 %. Findings revealed the presence of quorum molecules (AHLs) in beef meat throughout the spoilage process and spices can acts as quorum quenchers to influence the spoilage rate by reducing AHLs production.
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Affiliation(s)
- Venkadesaperumal Gopu
- Department of Food Science and Technology, Pondicherry University, Puducherry, 605013 India
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Inhibition of biofilm development and spoilage potential of Shewanella baltica by quorum sensing signal in cell-free supernatant from Pseudomonas fluorescens. Int J Food Microbiol 2016; 230:73-80. [PMID: 27149651 DOI: 10.1016/j.ijfoodmicro.2016.04.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 04/06/2016] [Accepted: 04/11/2016] [Indexed: 11/21/2022]
Abstract
The objective of this study was to in vitro evaluate the effect of a cell-free supernatant (CFS) containing quorum sensing (QS) signal of Pseudomonas fluorescens on the growth, biofilm development and spoilage potential of Shewanella baltica, and preliminarily assess the interactive influences of various chemically synthesized autoinducers on spoilage phenotypes of S. baltica. PF01 strain isolated from spoiled Pseudosciaen crocea was identified P. fluorescens. The addition of 25% and 50% CFS to S. baltica culture had no effect on the growth rate during the lag and exponential phase, however, caused cell decline during the stationary phase. The presence of CFS from P. fluorescens significantly inhibited biofilm development, and greatly decreased the production of trimethylamine (TMA) and biogenic amino in S. baltica. Various signal molecules of QS in the CFS of P. fluorescens culture were detected, including seven N-acyl-l-homoserine lactones (AHLs), autoinducer-2 (AI-2) and two diketopiperazines (DKPs). Exogenous supplement of synthesized seven AHLs containing in the CFS decreased biofilm formation and TMA production in S. baltica, while exposure to exogenous cyclo-(l-Pro-l-Leu) was showed to promote spoilage potential, which revealed that S. baltica also sense the two QS molecules. Furthermore, the stimulating effect of cyclo-(l-Pro-l-Leu) was affected when AHL was simultaneously added, suggesting that the inhibitory activity of spoilage phenotypes in S. baltica might be attributed to a competitive effect of these QS compounds in the CFS of P. fluorescens. The present studies provide a good basis for future research on the role of QS in the regulation of spoilage microbial flora.
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Bai A J, Rai Vittal R. Quorum Sensing Regulation and Inhibition of Exoenzyme Production and Biofilm Formation in the Food Spoilage BacteriaPseudomonas psychrophilaPSPF19. FOOD BIOTECHNOL 2014. [DOI: 10.1080/08905436.2014.963601] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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11
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Blana VA, Nychas GJE. Presence of quorum sensing signal molecules in minced beef stored under various temperature and packaging conditions. Int J Food Microbiol 2014; 173:1-8. [DOI: 10.1016/j.ijfoodmicro.2013.11.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 11/21/2013] [Accepted: 11/26/2013] [Indexed: 10/25/2022]
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12
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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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Abstract
Food spoilage may be defined as a process that renders a product undesirable or unacceptable for consumption and is the outcome of the biochemical activity of a microbial community that eventually dominates according to the prevailing ecological determinants. Although limited information are reported, this activity has been attributed to quorum sensing (QS). Consequently, the potential role of cell-to-cell communication in food spoilage and food safety should be more extensively elucidated. Such information would be helpful in designing approaches for manipulating these communication systems, thereby reducing or preventing, for instance, spoilage reactions or even controlling the expression of virulence factors. Due to the many reports in the literature on the fundamental features of QS, e.g., chemistry and definitions of QS compounds, in this minireview, we only allude to the types and chemistry of QS signaling molecules per se and to the (bioassay-based) methods of their detection and quantification, avoiding extensive documentation. Conversely, we attempt to provide insights into (i) the role of QS in food spoilage, (ii) the factors that may quench the activity of QS in foods and review the potential QS inhibitors that might "mislead" the bacterial coordination of spoilage activities and thus may be used as biopreservatives, and (iii) the future experimental approaches that need to be undertaken in order to explore the "gray" or "black" areas of QS, increase our understanding of how QS affects microbial behavior in foods, and assist in finding answers as to how we can exploit QS for the benefit of food preservation and food safety.
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Nicolaisen MH, Worm J, Jørgensen NO, Middelboe M, Nybroe O. Proteinase production inPseudomonas fluorescensON2 is affected by carbon sources and allows surface-attached but not planktonic cells to utilize protein for growth in lake water. FEMS Microbiol Ecol 2012; 80:168-78. [DOI: 10.1111/j.1574-6941.2011.01285.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 11/30/2011] [Accepted: 12/15/2011] [Indexed: 11/30/2022] Open
Affiliation(s)
- Mette H. Nicolaisen
- Genetics and Microbiology Section; Department of Agriculture and Ecology; University of Copenhagen; Frederiksberg; Denmark
| | - Jakob Worm
- Genetics and Microbiology Section; Department of Agriculture and Ecology; University of Copenhagen; Frederiksberg; Denmark
| | - Niels O.G. Jørgensen
- Genetics and Microbiology Section; Department of Agriculture and Ecology; University of Copenhagen; Frederiksberg; Denmark
| | - Mathias Middelboe
- Marine Biological Section; Department of Biology; University of Copenhagen; Helsingør; Denmark
| | - Ole Nybroe
- Genetics and Microbiology Section; Department of Agriculture and Ecology; University of Copenhagen; Frederiksberg; Denmark
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Blana VA, Doulgeraki AI, Nychas GJE. Autoinducer-2-like activity in lactic acid bacteria isolated from minced beef packaged under modified atmospheres. J Food Prot 2011; 74:631-5. [PMID: 21477479 DOI: 10.4315/0362-028x.jfp-10-276] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Fifteen fingerprints (assigned to Leuconostoc spp., Leuconostoc mesenteroides, Weissella viridescens, Leuconostoc citreum, and Lactobacillus sakei) of 89 lactic acid bacteria (LAB) isolated from minced beef stored under modified atmospheres at various temperatures were screened for their ability to exhibit autoinducer-2 (AI-2)-like activity under certain growth conditions. Cellfree meat extracts (CFME) were collected at the same time as the LAB isolates and tested for the presence of AI-2-like molecules. All bioassays were conducted using the Vibrio harveyi BAA-1117 (sensor 1(-), sensor 2(+)) biosensor strain. The possible inhibitory effect of meat extracts on the activity of the biosensor strain was also evaluated. AI-2-like activity was observed for Leuconostoc spp. isolates, but none of the L. sakei strains produced detectable AI-2-like activity. The AI-2-like activity was evident mainly associated with the Leuconostoc sp. B 233 strain, which was the dominant isolate recovered from storage at 10 and 15°C and at the initial and middle stages of storage at chill temperatures (0 and 5°C). The tested CFME samples displayed low AI-2-like activity and inhibited AI-2 activity regardless of the indigenous bacterial populations. The LAB isolated during meat spoilage exhibited AI-2-like activity, whereas the LAB strains retrieved depended on storage time and temperature. The production of AI-2-like molecules may affect the dominance of different bacterial strains during storage. The results provide a basis for further research concerning the effect of storage temperature on the expression of genes encoding AI-2 activity and on the diversity of the ephemeral bacterial population.
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Affiliation(s)
- Vasiliki A Blana
- Laboratory of Microbiology and Biotechnology of Foods, Department of Food Science, Technology and Human Nutrition, Agricultural University of Athens, Iera Odos 75, Athens 11855, Greece
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