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Abstract
This article presents information related to emerging pathogens that are foodborne or have the potential to be foodborne including bacteria, viruses, and parasites. The phenotypic characteristics of these pathogens, their epidemiology, prevalence in foods, and transmission routes to humans as well as means for their control are also discussed.
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Establishment and preliminary application of oligonucleotide microarray assay for detection of food-borne toxigenic microorganisms. Eur Food Res Technol 2013. [DOI: 10.1007/s00217-013-1951-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Herzallah S, Lledó ML, Holley R. Influence of NaCl and NaNO3 on sinigrin hydrolysis by foodborne bacteria. J Food Prot 2011; 74:2162-8. [PMID: 22186059 DOI: 10.4315/0362-028x.jfp-11-284] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The glucosinolate sinigrin (SNG) is converted by endogenous plant myrosinase or by bacterial myrosinase-like activity to form the potent antimicrobial allyl isothiocyanate. In order to use SNG as a natural antimicrobial precursor in food, it became important to better understand the ability of bacteria to synthesize the enzyme(s) and understand factors influencing this synthesis at a constant SNG concentration. Eight spoilage, pathogenic, or starter culture bacteria were grown separately in medium containing individual or combined salts with SNG. SNG degradation by the bacteria and the formation of its major degradation product, allyl isothiocyanate, were followed for 12 days at 30 or 35°C. The bacterial strains varied in their ability to metabolize SNG, and this was enhanced by NaCl and/or NaNO(3). SNG hydrolysis took place after 4 days, and the greatest amount occurred by day 12. At 12 days, Escherichia coli O157:H7 showed the greatest capacity to hydrolyze SNG (45.3% degradation), followed by Staphylococcus carnosus (44.57%), while Pseudomonas fluorescens was not active against SNG. The ability of tested strains to metabolize SNG, in decreasing order, was as follows: Escherichia coli O157:H7 > Staphylococcus carnosus > Staphylococcus aureus > Pediococcus pentosaceus > Salmonella Typhimurium > Listeria monocytogenes > Enterococcus faecalis > Pseudomonas fluorescens.
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Affiliation(s)
- S Herzallah
- Department of Nutrition and Food Science, Mutah University, Karak, Jordan
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Wang H, Yang R, Liu Y, Zhang W, Zhao W, Zhang Y, Hua X. Effects of low dose gamma irradiation on microbial inactivation and physicochemical properties of fried shrimp (Penaeus vannamei). Int J Food Sci Technol 2010. [DOI: 10.1111/j.1365-2621.2010.02179.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Kanatt S, Chawla S, Chander R, Sharma A. Development of shelf-stable, ready-to-eat (RTE) shrimps (Penaeus indicus) using -radiation as one of the hurdles. Lebensm Wiss Technol 2006. [DOI: 10.1016/j.lwt.2005.03.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Wouafo M, Pouillot R, Kwetche PF, Tejiokem MC, Kamgno J, Fonkoua MC. An Acute Foodborne Outbreak Due to Plesiomonas shigelloides in Yaounde, Cameroon. Foodborne Pathog Dis 2006; 3:209-11. [PMID: 16761948 DOI: 10.1089/fpd.2006.3.209] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We investigated an acute foodborne outbreak in Yaounde, Cameroon, following a private party. Plesiomonas shigelloides, which has rarely been reported as the causative agent of foodborne outbreaks, was strongly suspected. The unusual short incubation period suggested the presence of a preformed toxin within the incriminated food.
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Annamalai T, Venkitanarayanan K. Expression of major cold shock proteins and genes by Yersinia enterocolitica in synthetic medium and foods. J Food Prot 2005; 68:2454-8. [PMID: 16300089 DOI: 10.4315/0362-028x-68.11.2454] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Yersinia enterocolitica is a psychrotrophic foodborne pathogen that has been implicated in outbreaks of foodborne illness involving cold-stored foods, especially milk and pork. A major mechanism bacteria use to adapt to cold is expression of cold shock proteins. The objective of this research was to study the expression of major cold shock proteins of Y. enterocolitica in Luria-Bertani (LB) broth, milk, and pork following a temperature downshift from 30 to 4 degrees C. Y. enterocolitica was inoculated into 10 ml of LB broth, sterile skim milk, or pork, and the samples were stored at 4 degrees C (cold shock) or 30 degrees C (control) for 0, 4, 8, 12, and 24 h. At each sampling time, total protein and total RNA were extracted from Y. enterocolitica harvested from LB broth, milk, and pork and subjected to two-dimensional gel electrophoresis and dot blot analysis. Two major cold shock proteins (CspA1 and CspA2) of approximately 7 kDa and their genes were expressed by Y. enterocolitica following cold shock. However, the CspA1 and CspA2 proteins were not expressed by Y. enterocolitica at 30 degrees C. Y. enterocolitica CspA1 and CspA2 were observed as early as 2 h of cold shock in cultures from LB broth and milk and at 8 h of cold shock in cultures from pork.
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Rao MS, Chander R, Sharma A. Development of Shelf-stable Intermediate-moisture Meat Products Using Active Edible ChitosanCoating and Irradiation. J Food Sci 2005. [DOI: 10.1111/j.1365-2621.2005.tb11475.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Al-Bachir M. The irradiation of spices, packaging materials and luncheon meat to improve the storage life of the end products. Int J Food Sci Technol 2005. [DOI: 10.1111/j.1365-2621.2004.00931.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Analisaram-se 200 amostras de diferentes produtos e locais do fluxograma de abate de frangos com o objetivo de identificar os pontos de contaminação da carne de frango por Aeromonas. Das 25 amostras analisadas para cada um dos oito pontos estudados foram isoladas Aeromonas spp. em nove (36%) amostras de penas, em 14 (56%) de fezes, em 18 (72%) de carcaças não evisceradas, evisceradas e resfriadas e em 20 (80%) de água do pré-resfriamento. Não foram isoladas Aeromonas spp. da água de abastecimento da indústria e da água do tanque de escaldagem. Foram identificadas as espécies, Aeromonas hydrophila em 39 (15,2%) amostras, A. sobria em 69 (26,9%), A. caviae em 87 (34%), A. veronii em 18 (7%), A. schubertii em três (1,2%), A. trota em duas (0,8%) e A. jandaei em uma (0,4%). O resultado sugere que independente do controle higiênico-sanitário adotado na indústria, as carcaças de frangos podem se contaminar já a partir de sua obtenção, determinando o aparecimento de Aeromonas em carcaças resfriadas e prontas para a comercialização.
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Kanatt SR, Chawla SP, Chander R, Bongirwar DR. Shelf-stable and safe intermediate-moisture meat products using hurdle technology. J Food Prot 2002; 65:1628-31. [PMID: 12380750 DOI: 10.4315/0362-028x-65.10.1628] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A number of ready-to-use shelf-stable intermediate-moisture (IM) spiced mutton and spiced chicken products were developed with a combination of hurdles (reduced moisture, vacuum packing, and irradiation). The water activity of the products was reduced to about 0.80 either by grilling or by hot-air drying. These IM products were vacuum packed and subjected to gamma radiation processing at 0 to 10 kGy. Microbiological analyses revealed a radiation dose-dependent reduction in total viable counts and in numbers of Staphylococcus species. IM meat products that did not undergo radiation treatment showed visible mold growth within 2 months. The products subjected to irradiation at 10 kGy showed an absence of viable microorganisms and also retained high sensory acceptability for up to 9 months at ambient temperatures.
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Affiliation(s)
- Sweetie R Kanatt
- Food Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, India
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McMahon CM, Byrne CM, Sheridan JJ, McDowell DA, Blair IS, Hegarty T. The effect of culture growth phase on induction of the heat shock response in Yersinia enterocolitica and Listeria monocytogenes. J Appl Microbiol 2000; 89:198-206. [PMID: 10971751 DOI: 10.1046/j.1365-2672.2000.01097.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effect of culture growth phase on induction of the heat shock response in Yersinia enterocolitica and Listeria monocytogenes, was examined. Exponential or stationary preconditioned cultures were heat shocked and survivor numbers estimated using selective and overlay/resuscitation recovery techniques. The results indicate that prior heat shock induced increased heat resistance in both micro-organisms to higher heat treatments. Heat-shocked cells of each micro-organism were able to survive much longer than non-heat-shocked cells when heated at 55 degrees C. The size of the change in heat resistance between heat-shocked and non-heat-shocked cells was greatest for exponential cultures (X:X). Results indicate that the overall relative thermal resistance of each pathogen was dependent on cell growth phase. Stationary cultures (S:S) were significantly (P < 0.01) more thermotolerant than exponential cultures (X:X) under identical processing conditions. Under most conditions, the use of an overlay/resuscitation recovery medium resulted in higher D-values (P < 0.05) compared with a selective recovery medium.
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Affiliation(s)
- C M McMahon
- The National Food Centre, Teagasc, Dublin, Ireland.
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Thomas C, O'Beirne D. Evaluation of the impact of short-term temperature abuse on the microbiology and shelf life of a model ready-to-use vegetable combination product. Int J Food Microbiol 2000; 59:47-57. [PMID: 10946838 DOI: 10.1016/s0168-1605(00)00290-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The growth dynamics of indigenous aerobic mesophilic populations (AMP), lactic acid bacteria (LAB) and inoculated (Listeria spp.) microbial populations on cooked and fresh vegetable products, packaged as separate entities and in combination, subjected to temperature fluctuation, were assessed. Microbial proliferation was temperature and product dependent, being most pronounced at 12 degrees C in all products with maximum growth rates of 0.140, 0.175 and 0.126 log10 CFU/g per h being identified for Listeria, aerobic mesophilic and LAB populations, respectively. Listeria spp. and AMP generally demonstrated higher rates of growth within products containing cooked vegetables. Prolonged storage at 3 degrees C resulted in a reduced ability by AMP and Listeria spp. to proliferate upon exposure to growth temperatures; this was not the case with LAB populations. Comparison of Listeria population estimates made using selective (Oxford) and non-selective (nutrient agar) identified reduced recovery on the former. The magnitude of the deviation increased with the duration of exposure of Listeria populations to 3 degrees C with recoveries on selective systems being reduced by 6.3% immediately after inoculation and 82.3% after 168 h at 3 degrees C, respectively. Growth of populations associated with exposure to abuse temperatures was not accompanied by significant changes in product colour (P < 0.05).
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Affiliation(s)
- C Thomas
- Food Science Research Centre, Department of Life Sciences, University of Limerick, Ireland.
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Bolton DJ, McMahon CM, Doherty AM, Sheridan JJ, McDowell DA, Blair IS, Harrington D. Thermal inactivation of Listeria monocytogenes and Yersinia enterocolitica in minced beef under laboratory conditions and in sous-vide prepared minced and solid beef cooked in a commercial retort. J Appl Microbiol 2000; 88:626-32. [PMID: 10792520 DOI: 10.1046/j.1365-2672.2000.01001.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
D-values were obtained for Listeria monocytogenes and Yersinia enterocolitica at 50, 55 and 60 degrees C in vacuum-packed minced beef samples heated in a laboratory water-bath. The experiment was repeated using vacutainers, which allowed heating of the beef to the desired temperature before inoculation. D-values of between 0.15 and 36.1 min were obtained for L. monocytogenes. Pre-heating the beef samples significantly affected (P < 0.05) the D60 value only. D-values for Y. enterocolitica ranged from 0.55 to 21.2 min and all the D-values were significantly different (P < 0.05) after pre-heating. In general, the D-values obtained for core inoculated solid beef samples were significantly higher (P < 0.05) than those generated in minced beef when heated in a Barriquand Steriflow commercial retort.
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Affiliation(s)
- D J Bolton
- The National Food Centre, Teagasc, Dunsinea, Castleknock, Dublin 15, Ireland.
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Nortjé G, Vorster S, Greebe R, Steyn P. Occurrence of Bacillus cereus and Yersinia enterocolitica in South African retail meats. Food Microbiol 1999. [DOI: 10.1006/fmic.1998.0240] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Breidt F, Fleming HP. Modeling of the competitive growth of Listeria monocytogenes and Lactococcus lactis in vegetable broth. Appl Environ Microbiol 1998; 64:3159-65. [PMID: 9726854 PMCID: PMC106704 DOI: 10.1128/aem.64.9.3159-3165.1998] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/1998] [Accepted: 06/10/1998] [Indexed: 11/20/2022] Open
Abstract
Current mathematical models used by food microbiologists do not address the issue of competitive growth in mixed cultures of bacteria. We developed a mathematical model which consists of a system of nonlinear differential equations describing the growth of competing bacterial cell cultures. In this model, bacterial cell growth is limited by the accumulation of protonated lactic acid and decreasing pH. In our experimental system, pure and mixed cultures of Lactococcus lactis and Listeria monocytogenes were grown in a vegetable broth medium. Predictions of the model indicate that pH is the primary factor that limits the growth of L. monocytogenes in competition with a strain of L. lactis which does not produce the bacteriocin nisin. The model also predicts the values of parameters that affect the growth and death of the competing populations. Further development of this model will incorporate the effects of additional inhibitors, such as bacteriocins, and may aid in the selection of lactic acid bacterium cultures for use in competitive inhibition of pathogens in minimally processed foods.
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Affiliation(s)
- F Breidt
- Agricultural Research Service, U.S. Department of Agriculture, and North Carolina Agricultural Research Service, Department of Food Science, North Carolina State University, Raleigh, North Carolina 27695-7624, USA.
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Panisello P, Quantick P. Application of Food MicroModel predictive software in the development of Hazard Analysis Critical Control Point (HACCP) systems. Food Microbiol 1998. [DOI: 10.1006/fmic.1998.0195] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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DOHERTY ALICEM, McMAHON CAROLM, SHERIDAN J, BLAIR I, McDOWELL D, HEGARTY T. THERMAL RESISTANCE OF YERSINIA ENTEROCOLITICA AND LISTERIA MONOCYTOGENES IN MEAT AND POTATO SUBSTRATES. J Food Saf 1998. [DOI: 10.1111/j.1745-4565.1998.tb00204.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Dieuleveux V, Van Der Pyl D, Chataud J, Gueguen M. Purification and characterization of anti-Listeria compounds produced by Geotrichum candidum. Appl Environ Microbiol 1998; 64:800-3. [PMID: 9464426 PMCID: PMC106124 DOI: 10.1128/aem.64.2.800-803.1998] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/1997] [Accepted: 11/21/1997] [Indexed: 02/06/2023] Open
Abstract
Geotrichum candidum can produce and excrete compounds that inhibit Listeria monocytogenes. These were purified by ultrafiltration, centrifugal partition chromatography, thin-layer chromatography, gel filtration, and high-pressure liquid chromatography, and analyzed by liquid chromatography-mass spectrometry, infrared spectrometry, nuclear magnetic resonance spectrometry, and optical rotation. Two inhibitors were identified: D-3-phenyllactic acid and D-3-indollactic acid.
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Affiliation(s)
- V Dieuleveux
- Laboratoire de Microbiologie Alimentaire, Institut de Recherche en Biologie Appliquée, Université de Caen, France
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CAMPOS CARMENA, MAZZOTTA ALEJANDROS, MONTVILLE THOMASJ. INHIBITION OF LISTERIA MONOCYTOGENES BY CARNOBACTERIUM PISCICOLA IN VACUUM-PACKAGED COOKED CHICKEN AT REFRIGERATION TEMPERATURES. J Food Saf 1997. [DOI: 10.1111/j.1745-4565.1997.tb00184.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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JUNEJA VIJAYK, MARMER BENNES, CALL JEFFREYE. INFLUENCE OF MODIFIED ATMOSPHERE PACKAGING ON GROWTH OF CLOSTRIDIUM PERFRINGENS IN COOKED TURKEY. J Food Saf 1996. [DOI: 10.1111/j.1745-4565.1996.tb00155.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Montville TJ, Bruno ME. Evidence that dissipation of proton motive force is a common mechanism of action for bacteriocins and other antimicrobial proteins. Int J Food Microbiol 1994; 24:53-74. [PMID: 7703030 DOI: 10.1016/0168-1605(94)90106-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
While bacteriocins from lactic acid bacteria (LAB) have generated tremendous interest among food microbiologists, they are not unique. The biosphere is awash with antimicrobial proteins such as colicins, defensins, cecropins, and magainins. These proteins share many characteristics. They are low molecular weight, cationic, amphiphilic, tend to aggregate and are benign to the producing organism. In cases where the mode of action has been investigated, the cell membrane appears to be the site of action. There is increasing evidence that bacteriocins from many bacterial genera also share these characteristics. After a brief introduction on the significance of LAB bacteriocins, this review provides some background on proton motive force. Current studies of mechanisms for various bacteriocins are reviewed. Evidence is then introduced that bacteriocins produced by lactic acid bacteria act by the common mechanism of depleting proton motive force. The role and importance of energized membranes in this process is examined. These observations are linked to literature which demonstrates that many other classes of antimicrobial proteins act by the same mechanism. Questions regarding the role of receptor proteins and the physical mechanism by which PMF is depleted remain unresolved.
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Affiliation(s)
- T J Montville
- New Jersey Agricultural Experiment Station, Department of Food Science, Cook College, Rutgers, State University of New Jersey, New Brunswick 08903-0231
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McClure PJ, Cole MB, Davies KW. An example of the stages in the development of a predictive mathematical model for microbial growth: the effects of NaCl, pH and temperature on the growth of Aeromonas hydrophila. Int J Food Microbiol 1994; 23:359-75. [PMID: 7873337 DOI: 10.1016/0168-1605(94)90163-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The stages involved in developing a predictive model are illustrated using data describing the effects of temperature (3-20 degrees C), NaCl concentration (0.5-4.5% w/v) and pH (4.6-7.0) on the aerobic growth of Aeromonas hydrophila (cocktail of 6 strains). Optical density measurements using micro-titre plates were used as an initial screen, to determine the appropriate sampling times for viable counts to be made and to determine the approximate boundaries for growth. Growth curves were generated from viable counts and fitted using a modified Gompertz equation. Quadratic response surface equations were fitted to the log of lag and generation times, in response to the variables of temperature, NaCl and pH (in terms of hydrogen ion concentration). The effects of various combinations of these controlling factors are described. Comparisons between predicted growth rates and lag times from our response surface equations and other models for growth of A. hydrophila, developed with viable count data and optical density measurements, are made, together with comparisons with data from the literature on the growth of this bacterium in foods.
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Affiliation(s)
- P J McClure
- Unilever Research Laboratory, Sharnbrook, UK
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Naclerio G, Ricca E, Sacco M, De Felice M. Antimicrobial activity of a newly identified bacteriocin of Bacillus cereus. Appl Environ Microbiol 1993; 59:4313-6. [PMID: 8285719 PMCID: PMC195902 DOI: 10.1128/aem.59.12.4313-4316.1993] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A bacteriocin-producing Bacillus cereus strain was isolated. The bacteriocin, here called cerein, was shown to be active specifically against other B. cereus strains and inactive against all other bacterial species tested. Cerein was detected in the culture supernatants of stationary-phase cells, and its appearance was inhibited by induction of sporulation. The bacterial activity of cerein was insensitive to organic solvents and nonproteolytic enzymes, partially stable to heat, and active over a wide range of pH values. Direct detection of antimicrobial activity on sodium dodecyl sulfate-polyacrylamide gel suggested an apparent molecular mass of about 9 kDa.
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Affiliation(s)
- G Naclerio
- Department of General and Environmental Physiology, University Federico II, Naples, Italy
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Winkowski K, Crandall AD, Montville TJ. Inhibition of Listeria monocytogenes by Lactobacillus bavaricus MN in beef systems at refrigeration temperatures. Appl Environ Microbiol 1993; 59:2552-7. [PMID: 8368843 PMCID: PMC182319 DOI: 10.1128/aem.59.8.2552-2557.1993] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The ability of Lactobacillus bavaricus, a meat isolate, to inhibit the growth of three Listeria monocytogenes strains was examined in three beef systems: beef cubes, beef cubes in gravy, and beef cubes in gravy containing glucose. The beef was minimally heat treated, inoculated with L. bavaricus at 10(5) or 10(3) CFU/g and L. monocytogenes at 10(2) CFU/g, vacuum sealed, and stored at 4 or 10 degrees C. The meat samples were monitored for microbial growth, pH, and bacteriocin production. The pathogen was inhibited by L. bavaricus MN. At 4 degrees C, L. monocytogenes was inhibited or killed depending on the initial inoculum level of L. bavaricus. At 10 degrees C, at least a 10-fold reduction of the pathogen occurred, except in the beef without gravy. This system showed a transient inhibition of the pathogen during the first week of storage followed by growth to control levels by the end of the incubation period. Bacteriocin was detected in the samples, and inhibition could not be attributed to acidification. Low refrigeration temperatures significantly (P < or = 0.05) enhanced L. monocytogenes inhibition. Moreover, the addition of glucose-containing gravy and the higher inoculum level of L. bavaricus were significantly (P < or = 0.05) more effective in reducing L. monocytogenes populations in most of the systems studied.
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Affiliation(s)
- K Winkowski
- Department of Food Science, Cook College, Rutgers, State University, New Brunswick 08903
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Grant IR, Nixon CR, Patterson MF. Effect of low-dose irradiation on growth of and toxin production by Staphylococcus aureus and Bacillus cereus in roast beef and gravy. Int J Food Microbiol 1993; 18:25-36. [PMID: 8466810 DOI: 10.1016/0168-1605(93)90004-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effect of irradiation (2 kGy) on growth of and toxin production by Staphylococcus aureus and Bacillus cereus in roast beef and gravy during storage at abuse temperatures (15 and 22 degrees C) was assessed by inoculation studies. Irradiation resulted in a 3-4 log10 reduction in numbers of both pathogens. Whenever B. cereus and S. aureus numbers reached 10(6) and 10(7) cfu/g, respectively, during storage their toxins were detectable. As the time taken to attain these levels was longer in irradiated than in unirradiated samples, toxin production by both pathogens was delayed by irradiation. When samples initially containing low levels (10(2)/g) of S. aureus were irradiated no toxin was produced during subsequent storage at 15 or 22 degrees C. Diarrhoeal toxin produced by B. cereus was detected after 2 days at 22 degrees C, but not at 15 degrees C, in samples containing 10(2) cells/g prior to irradiation. When higher numbers (10(6)/g) of either pathogen were present prior to irradiation, toxins were produced by both pathogens at 22 degrees C, but not at 15 degrees C. Microbial competition had an effect on the growth of B. cereus and S. aureus after irradiation when a low initial inoculum was applied. However, when a higher inoculum was used the pathogens outnumbered their competitors and competition effects were less important. It was concluded that low-dose irradiation would improve the microbiological safety of roast beef and gravy.
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Affiliation(s)
- I R Grant
- Department of Food Microbiology, Queen's University of Belfast, Northern Ireland, UK
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