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Sample records for monocytogenes inoculated 4-5

  1. Survival of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes on inoculated walnut kernels during storage

    National Research Council Canada - National Science Library

    Blessington, Tyann; Mitcham, Elizabeth J; Harris, Linda J

    2012-01-01

    ...:H7, and Listeria monocytogenes was evaluated on walnut kernels. Kernels were separately inoculated with an aqueous preparation of the pathogens at 3 to 10 log CFU/g, dried for 7 days, and then stored at 23...

  2. Inhibitory Effect of Nisin on Listeria monocytogenes Inoculated into Surimi and Minced Meat

    Directory of Open Access Journals (Sweden)

    Masoud Rezaei

    2012-02-01

    Full Text Available Background & Objective: Listeria monocytogenes has already established as an important food born pathogen which induce listeriosis in human. Use of bacteriocins to provide food safety has been increased dramatically. Nisin has a wide spectrum inhibitory effect than the other bacteriocins and inhibits food-borne pathogens such as L. monocytogenes and many other Gram-positive spoilage microorganisms. The purpose of this study was to investigate the inhibitory effect of Nisin on population of Listeria monocytogenes and the role of changes in food components on the antilisterial properties of Nisin. Materials & Methods: The minced meat and surimi samples were inoculated by 1×104 cfu/g of L. monocytogenes. Then samples exposed to Nisin at the levels of 500 or 1000 IU/g were prepared. All treatments after packaging in plastic bags were kept for 12 days at refrigerator temperature. Samples were cultured on CHROMagarTM Listeria every 2 days and the number of listeria monocytogenes was counted. Results: two different concentrations of Nisin (500 or 1000 IU/g was not able to inhibit L. monocytogenes below the acceptable level for raw food (100 cells per g in minced meat and surimi of silver carp. But the number of bacteria reduces more in fish surimi as compared to the mince meal. Also, antilisterial activity of Nisin was reduced during the storage period. Conclusion: Inhibitory property of Nisin against L. monocytogenes in surimi significantly was higher than the minced (P<0.05. So it is possible the antilisterial properties of Nisin will increase by elimination of some enzymes during processing.

  3. Atmospheric Cold Plasma Inactivation of Escherichia Coli, Salmonella Enterica Serovar Typhimurium and Listeria Monocytogenes Inoculated on Fresh Produce

    OpenAIRE

    2014-01-01

    Atmospheric cold plasma (ACP) represents a potential alternative to traditional methods for non-thermal decontamination of foods. In this study, the antimicrobial efficacy of a novel dielectric barrier discharge ACP device against Escherichia coli, Salmonella enterica Typhimurium and Listeria monocytogenes inoculated on cherry tomatoes and strawberries, was examined. Bacteria were spot inoculated on the produce surface, air dried and sealed inside a rigid polypropylene container. Samples were...

  4. Effects of irradiation and fumaric acid treatment on the inactivation of Listeria monocytogenes and Salmonella typhimurium inoculated on sliced ham

    Science.gov (United States)

    Song, Hyeon-Jeong; Lee, Ji-Hye; Song, Kyung Bin

    2011-11-01

    To examine the effects of fumaric acid and electron beam irradiation on the inactivation of foodborne pathogens in ready-to-eat meat products, sliced ham was inoculated with Listeria monocytogenes and Salmonella typhimurium. The inoculated ham slices were treated with 0.5% fumaric acid or electron beam irradiation at 2 kGy. Fumaric acid treatment reduced the populations of L. monocytogenes and S. typhimurium by approximately 1 log CFU/g compared to control populations. In contrast, electron beam irradiation decreased the populations of S. typhimurium and L. monocytogenes by 3.78 and 2.42 log CFU/g, respectively. These results suggest that electron beam irradiation is a better and appropriate technique for improving the microbial safety of sliced ham.

  5. Effects of irradiation and fumaric acid treatment on the inactivation of Listeria monocytogenes and Salmonella typhimurium inoculated on sliced ham

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hyeon-Jeong; Lee, Ji-Hye [Department of Food Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Song, Kyung Bin, E-mail: kbsong@cnu.ac.kr [Department of Food Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2011-11-15

    To examine the effects of fumaric acid and electron beam irradiation on the inactivation of foodborne pathogens in ready-to-eat meat products, sliced ham was inoculated with Listeria monocytogenes and Salmonella typhimurium. The inoculated ham slices were treated with 0.5% fumaric acid or electron beam irradiation at 2 kGy. Fumaric acid treatment reduced the populations of L. monocytogenes and S. typhimurium by approximately 1 log CFU/g compared to control populations. In contrast, electron beam irradiation decreased the populations of S. typhimurium and L. monocytogenes by 3.78 and 2.42 log CFU/g, respectively. These results suggest that electron beam irradiation is a better and appropriate technique for improving the microbial safety of sliced ham. - Highlights: > We compare irradiation and fumaric acid treatment on the inactivation of pathogens. > We examine changes in the populations of L. monocytogenes and S. typhimurium. > Irradiation at 2 kGy is more effective in sliced ham than fumaric acid treatment. > Low-dose irradiation can improve the microbial safety of sliced ham during storage.

  6. Atmospheric cold plasma inactivation of Escherichia coli, Salmonella enterica serovar Typhimurium and Listeria monocytogenes inoculated on fresh produce.

    Science.gov (United States)

    Ziuzina, D; Patil, S; Cullen, P J; Keener, K M; Bourke, P

    2014-09-01

    Atmospheric cold plasma (ACP) represents a potential alternative to traditional methods for non-thermal decontamination of foods. In this study, the antimicrobial efficacy of a novel dielectric barrier discharge ACP device against Escherichia coli, Salmonella enterica Typhimurium and Listeria monocytogenes inoculated on cherry tomatoes and strawberries, was examined. Bacteria were spot inoculated on the produce surface, air dried and sealed inside a rigid polypropylene container. Samples were indirectly exposed (i.e. placed outside plasma discharge) to a high voltage (70 kVRMS) air ACP and subsequently stored at room temperature for 24 h. ACP treatment for 10, 60 and 120 s resulted in reduction of Salmonella, E. coli and L. monocytogenes populations on tomato to undetectable levels from initial populations of 3.1, 6.3, and 6.7 log10 CFU/sample, respectively. However, an extended ACP treatment time was necessary to reduce bacterial populations attached on the more complex surface of strawberries. Treatment time for 300 s resulted in reduction of E. coli, Salmonella and L. monocytogenes populations by 3.5, 3.8 and 4.2 log10 CFU/sample, respectively, and also effectively reduced the background microflora of tomatoes.

  7. Effect of several food ingredients on radiation inactivation of Escherichia coli and Listeria monocytogenes inoculated into ground pork

    Science.gov (United States)

    Yun, Hyejeong; Lacroix, Monique; Jung, Samooel; Kim, Keehyuk; Lee, Ju Woon; Jo, Cheorun

    2011-09-01

    The objective of this study was to examine the effects of several food ingredients on the relative radiation sensitivity (RRS) of Escherichia coli and Listeria monocytogenes inoculated onto ground pork. Garlic, leek, onion, and ginger were prepared in 3 different forms; pressurized, freeze-dried, and 70% ethanol extracted. The prepared food ingredients were subdivided into 2 groups, non-irradiated and irradiated with 5 kGy of gamma irradiation, before addition to ground pork. The prepared food ingredients were added at concentrations of 1% and 5% (w/w) into radiation-sterilized ground pork and inoculated with E. coli and L. monocytogenes (10 6 CFU/mL). For E. coli inoculated pork, the most efficient ingredient was ethanol extracted leek (RRS=3.89), followed by freeze-dried ginger and leek (RRS=3.66 and 3.63, respectively) when used without pasteurization. However, when the food ingredients were irradiation-pasteurized, the freeze-dried ginger showed the highest RRS (4.10). When 5% natural materials were added, RRS was the highest for freeze-dried and ethanol extracted onion (4.44 and 4.65, respectively). For L. monocytogenes, the RRS was relatively lower than E. coli in general. The most efficient material was pressurized and freeze-dried onion (RRS=2.13 and 2.08, respectively) at a concentration of 1%. No increase in RRS was observed at increased concentration of food ingredients. These results suggest that the addition of particular food ingredients increased the efficiency of radiation-sterilization. However, changes in RRS were dependent on the species of microorganism as well as the form of the food ingredients.

  8. Effect of several food ingredients on radiation inactivation of Escherichia coli and Listeria monocytogenes inoculated into ground pork

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Hyejeong [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Lacroix, Monique [Canadian Irradiation Center, Research Laboratory in Science Applied to Food, INRS-Institut Armand-Frappier, Qebec (Canada); Jung, Samooel [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Kim, Keehyuk [Department of Culinary Nutrition, Woosong University, Daejeon 300-718 (Korea, Republic of); Lee, Ju Woon [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Jo, Cheorun, E-mail: cheorun@cnu.ac.kr [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2011-09-15

    The objective of this study was to examine the effects of several food ingredients on the relative radiation sensitivity (RRS) of Escherichia coli and Listeria monocytogenes inoculated onto ground pork. Garlic, leek, onion, and ginger were prepared in 3 different forms; pressurized, freeze-dried, and 70% ethanol extracted. The prepared food ingredients were subdivided into 2 groups, non-irradiated and irradiated with 5 kGy of gamma irradiation, before addition to ground pork. The prepared food ingredients were added at concentrations of 1% and 5% (w/w) into radiation-sterilized ground pork and inoculated with E. coli and L. monocytogenes (10{sup 6} CFU/mL). For E. coli inoculated pork, the most efficient ingredient was ethanol extracted leek (RRS=3.89), followed by freeze-dried ginger and leek (RRS=3.66 and 3.63, respectively) when used without pasteurization. However, when the food ingredients were irradiation-pasteurized, the freeze-dried ginger showed the highest RRS (4.10). When 5% natural materials were added, RRS was the highest for freeze-dried and ethanol extracted onion (4.44 and 4.65, respectively). For L. monocytogenes, the RRS was relatively lower than E. coli in general. The most efficient material was pressurized and freeze-dried onion (RRS=2.13 and 2.08, respectively) at a concentration of 1%. No increase in RRS was observed at increased concentration of food ingredients. These results suggest that the addition of particular food ingredients increased the efficiency of radiation-sterilization. However, changes in RRS were dependent on the species of microorganism as well as the form of the food ingredients. - Highlights: > Several food ingredients increased the efficiency of irradiation sterilization. > Different forms of food ingredients may affect the efficiency. > The increase of efficiency decreased the required irradiation dose, thereby avoiding sensory impairments of food.

  9. Evaluation of inoculation method and inoculum drying time for their effects on survival and efficiency of recovery of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes inoculated on the surface of tomatoes.

    Science.gov (United States)

    Lang, Megan M; Harris, Linda J; Beuchat, Larry R

    2004-04-01

    A study was undertaken to evaluate methods for applying inoculum and to examine the effect of inoculum drying time on survival and recovery of foodborne pathogens inoculated onto the surface of raw, ripe tomatoes. Five-strain mixtures of Escherichia coli O157:H7, Salmonella, or Listeria monocytogenes were applied to tomatoes by dip, spot, or spray inoculation methods. Inocula were dried for 1 or 24 h at 22 degrees C before tomatoes were treated with water (control) or chlorine (200 micrograms/ml). Significantly (alpha = 0.05) larger populations (CFU per tomato) of E. coli O157:H7 and Salmonella were recovered from dipinoculated tomatoes than from spot- or spray-inoculated tomatoes. This difference was attributed to larger numbers of cells adhering to tomatoes subjected to dip inoculation. Populations of E. coli O157:H7 and Salmonella recovered from spot- and spray-inoculated tomatoes containing the same initial number of cells were not significantly different. Significantly different L. monocytogenes population sizes were recovered from inoculated tomatoes (dip > spot > spray). Populations of pathogens recovered from tomatoes were significantly larger when inocula were dried for 1 h compared with 24 h. Significant differences (water > chlorine) were observed in the sizes of populations for all pathogens recovered from tomatoes treated with chlorine, regardless of inoculation method or drying time. Results indicate that inoculation method, drying time, and treatment affect survival and/or recovery of foodborne pathogens inoculated onto the surface of tomatoes. We recommend that spot inoculation with a drying time of 24 h at 22 degrees C be used with standard methods to determine the efficacy of chlorine and other sanitizers for killing foodborne pathogens on tomatoes.

  10. Effect of inoculation of Carnobacterium divergens V41, a bio-preservative strain against Listeria monocytogenes risk, on the microbiological, chemical and sensory quality of cold-smoked salmon.

    Science.gov (United States)

    Brillet, Anne; Pilet, Marie-France; Prevost, Hervé; Cardinal, Mireille; Leroi, Françoise

    2005-10-25

    The aim of this study was to develop a bio-preservation strategy for cold-smoked salmon (CSS) by the use of lactic acid bacteria previously selected for their capability to inhibit the growth of Listeria monocytogenes in the product. The spoiling potential of three Carnobacterium strains (Carnobacterium divergens V41, Carnobacterium piscicola V1 and SF668) was tested in sterile CSS blocks inoculated by 10(4-5) CFU g(-)(1) and stored under vacuum for 9 days at 4 degrees C followed by 19 days at 8 degrees C. C. divergens V41 grew a little faster than the other strains and none of the three carnobacteria showed any adverse effect on quality of the product, i.e. no off-odour detected by a trained panel, no total volatile basic nitrogen (TVBN) production, no acidification and no biogenic amine except a slight production of tyramine. An application on commercial CSS was tested by spraying C. divergens V41 (10(4-5) CFU g(-1)) on slices of four batches freshly processed in different smoke-houses. Microbial, chemical and sensory characteristics were weekly compared to a control during 4 weeks of vacuum storage. When the natural microflora was initially weak (two batches10(4-5) CFU g(-1)), no effect on the microflora, TVBN and biogenic amine production, nor on the sensory characteristics was observed in presence of C. divergens V41. In conclusion, bio-preservation of CSS using lactic acid bacteria such as C. divergens V41 is a promising way to inhibit the growth of pathogenic bacteria such as L. monocytogenes with low effect on the quality of the product.

  11. Chemical Composition, Antioxidant and Antimicrobial Activities of Thymus capitata Essential Oil with Its Preservative Effect against Listeria monocytogenes Inoculated in Minced Beef Meat

    Directory of Open Access Journals (Sweden)

    Nariman El Abed

    2014-01-01

    Full Text Available The chemical composition, antioxidant and antimicrobial activities, and the preservative effect of Thymus capitata essential oil against Listeria monocytogenes inoculated in minced beef meat were evaluated. The essential oil extracted was chemically analyzed by gas chromatography-mass spectrometry. Nineteen components were identified, of which carvacrol represented (88.89% of the oil. The antioxidant activity was assessed in vitro by using both the DPPH and the ABTS assays. The findings showed that the essential oil exhibited high antioxidant activity, which was comparable to the reference standards (BHT and ascorbic acid with IC50 values of 44.16 and 0.463 μg/mL determined by the free-radical scavenging DPPH and ABTS assays, respectively. Furthermore, the essential oil was evaluated for its antimicrobial activity using disc agar diffusion and microdilution methods. The results demonstrated that the zone of inhibition varied from moderate to strong (15–80 mm and the minimum inhibition concentration values ranged from 0.32 to 20 mg/mL. In addition, essential oil evaluated in vivo against Listeria monocytogenes showed clear and strong inhibitory effect. The application of 0.25 or 1% (v/w essential oil of T. capitata to minced beef significantly reduced the L. monocytogenes population when compared to those of control samples (P-value  <0.01.

  12. Chemical Composition, Antioxidant and Antimicrobial Activities of Thymus capitata Essential Oil with Its Preservative Effect against Listeria monocytogenes Inoculated in Minced Beef Meat.

    Science.gov (United States)

    El Abed, Nariman; Kaabi, Belhassen; Smaali, Mohamed Issam; Chabbouh, Meriem; Habibi, Kamel; Mejri, Mondher; Marzouki, Mohamed Nejib; Ben Hadj Ahmed, Sami

    2014-01-01

    The chemical composition, antioxidant and antimicrobial activities, and the preservative effect of Thymus capitata essential oil against Listeria monocytogenes inoculated in minced beef meat were evaluated. The essential oil extracted was chemically analyzed by gas chromatography-mass spectrometry. Nineteen components were identified, of which carvacrol represented (88.89%) of the oil. The antioxidant activity was assessed in vitro by using both the DPPH and the ABTS assays. The findings showed that the essential oil exhibited high antioxidant activity, which was comparable to the reference standards (BHT and ascorbic acid) with IC50 values of 44.16 and 0.463 μ g/mL determined by the free-radical scavenging DPPH and ABTS assays, respectively. Furthermore, the essential oil was evaluated for its antimicrobial activity using disc agar diffusion and microdilution methods. The results demonstrated that the zone of inhibition varied from moderate to strong (15-80 mm) and the minimum inhibition concentration values ranged from 0.32 to 20 mg/mL. In addition, essential oil evaluated in vivo against Listeria monocytogenes showed clear and strong inhibitory effect. The application of 0.25 or 1% (v/w) essential oil of T. capitata to minced beef significantly reduced the L. monocytogenes population when compared to those of control samples (P-value  <0.01).

  13. Reduction of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes with electrolyzed oxidizing water on inoculated hass avocados (Persea americana var. Hass).

    Science.gov (United States)

    Rodríguez-Garcia, O; González-Romero, V M; Fernández-Escartín, E

    2011-09-01

    This study was intended to evaluate the bactericidal effect of electrolyzed oxidizing water (EOW) and chlorinated water on populations of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes inoculated on avocados (Persea americana var. Hass). In the first experiment, inoculated avocados were treated with a water wash applied by spraying tap water containing 1 mg/liter free chlorine for 15 s (WW); WW treatment and then spraying sodium hypochlorite in water containing 75 mg/liter free chlorine for 15 s (Cl75); WW treatment and then spraying alkaline EOW for 30 s (AkEW) and then spraying acid EOW (AcEW) for 15 s; and spraying AkEW and then AcEW. In another experiment, the inoculated avocados were treated by spraying AkEW and then AcEW for 15, 30, 60, or 90 s. All three pathogen populations were lowered between 3.6 and 3.8 log cycles after WW treatment. The application of Cl75 did not produce any further reduction in counts, whereas AkEW and then AcEW treatment resulted in significantly lower bacterial counts for L. monocytogenes and E. coli O157:H7 but not for Salmonella. Treatments with AkEW and then AcEW produced a significant decrease in L. monocytogenes, Salmonella, and E. coli O157:H7 populations, with estimated log reductions of 3.9 to 5.2, 5.1 to 5.9, and 4.2 to 4.9 log CFU/cm², respectively. Spraying AcEW for more than 15 s did not produce any further decrease in counts of Salmonella or E. coli O157:H7, whereas L. monocytogenes counts were significantly lower after spraying AcEW for 60 s. Applying AkEW and then AcEW for 15 or 30 s seems to be an effective alternative to reduce bacterial pathogens on avocado surfaces.

  14. Viability of a multi-strain mixture of Listeria monocytogenes, Salmonella typhimurium, or Escherichia coli O157:H7 inoculated into the batter or onto the surface of a soudjouk-style fermented semi-dry sausage

    Science.gov (United States)

    Multi-strain mixtures of Listeria monocytogenes, Salmonella typhimurium, or Escherichia coli O157:H7 were separately inoculated either into soudjouk batter or onto the surface of slices of commercial soudjouk to levels of ca. 6.0 log10 CFU per gram or slice, respectively. After fermentation and dryi...

  15. Effect of acidified sodium chlorite, chlorine, and acidic electrolyzed water on Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes inoculated onto leafy greens.

    Science.gov (United States)

    Stopforth, J D; Mai, T; Kottapalli, B; Samadpour, M

    2008-03-01

    Recent foodborne outbreaks implicating spinach and lettuce have increased consumer concerns regarding the safety of fresh produce. While the most common commercial antimicrobial intervention for fresh produce is wash water containing 50 to 200 ppm chlorine, this study compares the effectiveness of acidified sodium chlorite, chlorine, and acidic electrolyzed water for inactivating Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes inoculated onto leafy greens. Fresh mixed greens were left uninoculated or inoculated with approximately 6 log CFU/g of E. coli O157:H7, Salmonella, and L. monocytogenes and treated by immersion for 60 or 90 s in different wash solutions (1:150, wt/vol), including 50 ppm of chlorine solution acidified to pH 6.5, acidic electrolyzed water (pH 2.1 +/- 0.2, oxygen reduction potential of 1,100 mV, 30 to 35 ppm of free chlorine), and acidified sodium chlorite (1,200 ppm, pH 2.5). Samples were neutralized and homogenized. Bacterial survival was determined by standard spread plating on selective media. Each test case (organism x treatment x time) was replicated twice with five samples per replicate. There was no difference (P > or = 0.05) in the time of immersion on the antimicrobial effectiveness of the treatments. Furthermore, there was no difference (P > or = 0.05) in survival of the three organisms regardless of treatment or time. Acidified sodium chlorite, resulted in reductions in populations of 3 to 3.8 log CFU/g and was more effective than chlorinated water (2.1 to 2.8 log CFU/g reduction). These results provide the produce industry with important information to assist in selection of effective antimicrobial strategies.

  16. The effects of X-ray radiation on Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica and Shigella flexneri inoculated on whole Roma tomatoes.

    Science.gov (United States)

    Mahmoud, Barakat S M

    2010-12-01

    In the last two decades several foodborne disease outbreaks associated with produce were reported. Tomatoes, in particular, have been associated with several multi-state Salmonella outbreaks. Inactivation of inoculated Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica and Shigella flexneri on whole Roma tomato surfaces by X-ray at 0.1, 0.5, 0.75, 1.0, and 1.5 kGy was studied. The main purpose of this study was to achieve a 5 log reduction in consistent with the recommendations of the National Advisory Committee on Microbiological Criteria for Foods. Moreover, the effect of X-ray on inherent microflora (mesophilic counts, psychrotrophic counts and yeast and mold counts) of untreated and treated Roma tomatoes, during storage at ambient temperature (22°C) for 20 days was also determined. Mixtures of three or two strains of each tested organism was spot inoculated (100 μl) onto the surface of Roma tomatoes (approximately 7-9 log per tomato), separately, and air-dried, followed by treatment with X-ray doses at 22°C and 55-60% relative humidity. Surviving bacterial populations on tomato surfaces were evaluated using a nonselective medium (tryptic soy agar) with a selective medium overlay for each bacteria; E. coli O157:H7 (CT-SMAC agar), L. monocytogenes (MOA), and S. enterica and S. flexneri (XLD). Treatment with X-ray significantly reduced the population of the tested pathogens on whole Roma tomato surfaces, compared with the control. Approximately 4.2, 2.3, 3.7 and 3.6 log CFU reduction of E. coli O157:H7, L. monocytogenes, S. enterica and S. flexneri per tomato were achieved by treatment with 0.75 kGy X-ray, respectively. More than a 5 log CFU reduction per tomato was achieved at 1.0 or 1.5 kGy X-ray for all tested pathogens. Furthermore, treatment with X-ray significantly reduced the inherent microflora on Roma tomatoes. Inherent levels were significantly (p<0.05) lower than the control sample throughout storage for 20 days.

  17. Inhibitory activity of Syzygium aromaticum and Cymbopogon citratus (DC. Stapf. essential oils against Listeria monocytogenes inoculated in bovine ground meat

    Directory of Open Access Journals (Sweden)

    Thales Leandro Coutinho de Oliveira

    2013-01-01

    Full Text Available This research evaluated the antimicrobial effect of the clove (Syzygium aromaticum and lemongrass (Cymbopogon citratus (DC. Stapf. essential oils (EOs against Listeria monocytogenes ATCC 19117 growth added to bovine ground meat stored under refrigeration (5 ± 2 °C for three days. The EOs, extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS, were tested in vitro using an agar well diffusion methodology for determination of Minimum Inhibitory Concentration (MIC. The MIC concentrations for both essential oils on culture tested of L. monocytogenes were 1.56%. The EOs concentrations applied in contaminated ground beef were 1.56, 3.125 and 6.25% (w/v based on MIC levels and possible activity reductions by food constituents. The bacteria populations were significantly reduced (p < 0.05 after one day of storage in ground meat samples treated with clove and lemongrass EOs at concentrations of 1.56%. There were no significant counts of L. monocytogenes in samples at the other concentrations of the two oils applied after the second day of storage. The sensory acceptability evaluation of the bovine ground meat samples treated with EOs showed that the addition at concentrations higher than 1.56% promote undesirable alterations of taste, odor and characteristic color. The application of EOs at low concentrations in food products can be used in combination with other preservation methods, such as refrigeration, to control pathogens and spoilage bacteria during shelf-life; which goes according to current market trends, where consumers are requesting natural products.

  18. Inhibitory activity of Syzygium aromaticum and Cymbopogon citratus (DC.) Stapf. essential oils against Listeria monocytogenes inoculated in bovine ground meat.

    Science.gov (United States)

    de Oliveira, Thales Leandro Coutinho; das Graças Cardoso, Maria; de Araújo Soares, Rodrigo; Ramos, Eduardo Mendes; Piccoli, Roberta Hilsdorf; Tebaldi, Victor Maximiliano Reis

    2013-01-01

    This research evaluated the antimicrobial effect of the clove (Syzygium aromaticum) and lemongrass (Cymbopogon citratus (DC.) Stapf.) essential oils (EOs) against Listeria monocytogenes ATCC 19117 growth added to bovine ground meat stored under refrigeration (5 ± 2 °C) for three days. The EOs, extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), were tested in vitro using an agar well diffusion methodology for determination of Minimum Inhibitory Concentration (MIC). The MIC concentrations for both essential oils on culture tested of L. monocytogenes were 1.56%. The EOs concentrations applied in contaminated ground beef were 1.56, 3.125 and 6.25% (w/v) based on MIC levels and possible activity reductions by food constituents. The bacteria populations were significantly reduced (p ≤ 0.05) after one day of storage in ground meat samples treated with clove and lemongrass EOs at concentrations of 1.56%. There were no significant counts of L. monocytogenes in samples at the other concentrations of the two oils applied after the second day of storage. The sensory acceptability evaluation of the bovine ground meat samples treated with EOs showed that the addition at concentrations higher than 1.56% promote undesirable alterations of taste, odor and characteristic color. The application of EOs at low concentrations in food products can be used in combination with other preservation methods, such as refrigeration, to control pathogens and spoilage bacteria during shelf-life; which goes according to current market trends, where consumers are requesting natural products.

  19. Inhibitory activity of Syzygium aromaticum and Cymbopogon citratus (DC.) Stapf. essential oils against Listeria monocytogenes inoculated in bovine ground meat

    Science.gov (United States)

    de Oliveira, Thales Leandro Coutinho; das Graças Cardoso, Maria; de Araújo Soares, Rodrigo; Ramos, Eduardo Mendes; Piccoli, Roberta Hilsdorf; Tebaldi, Victor Maximiliano Reis

    2013-01-01

    This research evaluated the antimicrobial effect of the clove (Syzygium aromaticum) and lemongrass (Cymbopogon citratus (DC.) Stapf.) essential oils (EOs) against Listeria monocytogenes ATCC 19117 growth added to bovine ground meat stored under refrigeration (5 ± 2 °C) for three days. The EOs, extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), were tested in vitro using an agar well diffusion methodology for determination of Minimum Inhibitory Concentration (MIC). The MIC concentrations for both essential oils on culture tested of L. monocytogenes were 1.56%. The EOs concentrations applied in contaminated ground beef were 1.56, 3.125 and 6.25% (w/v) based on MIC levels and possible activity reductions by food constituents. The bacteria populations were significantly reduced (p ≤ 0.05) after one day of storage in ground meat samples treated with clove and lemongrass EOs at concentrations of 1.56%. There were no significant counts of L. monocytogenes in samples at the other concentrations of the two oils applied after the second day of storage. The sensory acceptability evaluation of the bovine ground meat samples treated with EOs showed that the addition at concentrations higher than 1.56% promote undesirable alterations of taste, odor and characteristic color. The application of EOs at low concentrations in food products can be used in combination with other preservation methods, such as refrigeration, to control pathogens and spoilage bacteria during shelf-life; which goes according to current market trends, where consumers are requesting natural products. PMID:24294222

  20. Preliminary Study on the Effect of Fermented Cheese Whey on Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Goldcoast Populations Inoculated onto Fresh Organic Lettuce.

    Science.gov (United States)

    Santos, Maria I S; Lima, Ana I; Monteiro, Sara A V S; Ferreira, Ricardo M S B; Pedroso, Laurentina; Sousa, Isabel; Ferreira, Maria A S S

    2016-08-01

    Cheese whey fermented by an industrial starter consortium of lactic acid bacteria was evaluated for its antibacterial capacity to control a selection of pathogenic bacteria. For their relevance on outbreak reports related to vegetable consumption, this selection included Listeria monocytogenes, serotype 4b, Escherichia coli O157:H7, and Salmonella Goldcoast. Organically grown lettuce was inoculated with an inoculum level of ∼10(7) colony-forming unit (CFU)/mL and was left for about 1 h in a safety cabinet before washing with a perceptual solution of 75:25 (v/v) fermented whey in water, for 1 and 10 min. Cells of pathogens recovered were then counted and their number compared with that obtained for a similar treatment, but using a chlorine solution at 110 ppm. Results show that both treatments, either with chlorine or fermented whey, were able to significantly reduce (p whey may be as effective as the solution of chlorine used in industrial processes in reducing the pathogens under study (best efficacy shown for Salmonella), with the advantage of avoiding health risks arising from the formation of carcinogenic toxic chlorine derivates.

  1. Performance of a growth-no growth model for Listeria monocytogenes developed for mayonnaise-based salads: influence of strain variability, food matrix, inoculation level, and presence of sorbic and benzoic acid.

    Science.gov (United States)

    Vermeulen, A; Smigic, N; Rajkovic, A; Gysemans, K; Bernaerts, K; Geeraerd, A; Van Impe, J; Debevere, J; Devlieghere, F

    2007-09-01

    A previously developed growth-no growth model for Listeria monocytogenes, based on nutrient broth data and describing the influence of water activity (a(w)), pH, and acetic acid concentrations, was validated (i) for a variety of L. monocytogenes strains and (ii) in a laboratory-made, mayonnaise-based surimi salad (as an example of a mayonnaise-based salad). In these challenge tests, the influence of the inoculation level was tested as well. Also, the influence of chemical preservatives on the growth probability of L. monocytogenes in mayonnaise-based salads was determined. To evaluate the growth-no growth model performance on the validation data, four quantitative criteria are determined: concordance index, % correct predictions, % fail-dangerous, and % fail-safe. First, the growth probability of 11 L. monocytogenes strains, not used for model development, was assessed in nutrient broth under conditions within the interpolation region. Experimental results were compared with model predictions. Second, the growth-no growth model was assessed in a laboratory-made, sterile, mayonnaise-based surimi salad to identify a possible model completeness error related to the food matrix, making use of the above-mentioned validation criteria. Finally, the effect on L. monocytogenes of common chemical preservatives (sorbic and benzoic acid) at different concentrations under conditions typical of mayonnaise-based salads was determined. The study showed that the growth-no growth zone was properly predicted and consistent for all L. monocytogenes strains. A larger prediction error was observed under conditions within the transition zone between growth-no growth. However, in all cases, the classification between no growth (P = 0) and any growth (P > 0) occurred properly, which is most important for the food industry, where outgrowth needs to be prevented in all instances. The results in the sterile mayonnaise-based salad showed again that the growth-no growth zone was well predicted

  2. Viability of multi-strain mixtures of Listeria monocytogenes, Salmonella typhimurium, or Escherichia coli O157:H7 inoculated into the batter or onto the surface of a soudjouk-style fermented semi-dry sausage.

    Science.gov (United States)

    Porto-Fett, A C S; Hwang, C-A; Call, J E; Juneja, V K; Ingham, S C; Ingham, B H; Luchansky, J B

    2008-09-01

    The fate of Listeria monocytogenes, Salmonella typhimurium, or Escherichia coli O157:H7 were separately monitored both in and on soudjouk. Fermentation and drying alone reduced numbers of L. monocytogenes by 0.07 and 0.74 log(10)CFU/g for sausages fermented to pH 5.3 and 4.8, respectively, whereas numbers of S. typhimurium and E. coli O157:H7 were reduced by 1.52 and 3.51 log(10)CFU/g and 0.03 and 1.11 log(10)CFU/g, respectively. When sausages fermented to pH 5.3 or 4.8 were stored at 4, 10, or 21 degrees C, numbers of L. monocytogenes, S. typhimurium, and E. coli O157:H7 decreased by an additional 0.08-1.80, 0.88-3.74, and 0.68-3.17 log(10)CFU/g, respectively, within 30 days. Storage for 90 days of commercially manufactured soudjouk that was sliced and then surface inoculated with L. monocytogenes, S. typhimurium, and E. coli O157:H7 generated average D-values of ca. 10.1, 7.6, and 5.9 days at 4 degrees C; 6.4, 4.3, and 2.9 days at 10 degrees C; 1.4, 0.9, and 1.6 days at 21 degrees C; and 0.9, 1.4, and 0.25 days at 30 degrees C. Overall, fermentation to pH 4.8 and storage at 21 degrees C was the most effective treatment for reducing numbers of L. monocytogenes (2.54 log(10)CFU/g reduction), S. typhimurium (> or =5.23 log(10)CFU/g reduction), and E. coli O157:H7 (3.48 log(10)CFU/g reduction). In summary, soudjouk-style sausage does not provide a favorable environment for outgrowth/survival of these three pathogens.

  3. In vitro activity of naturally occurring peptides (defensins against Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Nascimento Maria da Graça F.

    1994-01-01

    Full Text Available Autoclaved distilled water samples were inoculated with L. monocytogenes strain V7 and strain VPH-1, and incubated aerobically, at 30 C for 48 hours. Each strain was tested individually, and growth curves were determined at 1, 2, 3, 4, 5, 21, 24, and 48 hours. The growth or survival of L. monocytogenes was similar for both strains, with survivors at 24 hour-incubation. The microbicidal activity of one synthetic cationic peptide (NP-2 was examined against L. monocytogenes strain V7, in a water system. Antibacterial activity of NP-2 (1, 5, and 10 g/ml was best expressed at 60 minute-incubation, with 10 g/ml of peptide, at 30 C.

  4. In vitro activity of naturally occurring peptides (defensins against Listeria monocytogenes Ação in vitro de peptídeos naturais (defensinas sobre Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Maria da Graça F. Nascimento

    1994-12-01

    Full Text Available Autoclaved distilled water samples were inoculated with L. monocytogenes strain V7 and strain VPH-1, and incubated aerobically, at 30 C for 48 hours. Each strain was tested individually, and growth curves were determined at 1, 2, 3, 4, 5, 21, 24, and 48 hours. The growth or survival of L. monocytogenes was similar for both strains, with survivors at 24 hour-incubation. The microbicidal activity of one synthetic cationic peptide (NP-2 was examined against L. monocytogenes strain V7, in a water system. Antibacterial activity of NP-2 (1, 5, and 10 g/ml was best expressed at 60 minute-incubation, with 10 g/ml of peptide, at 30 C.Amostras de água destilada, autoclavadas, foram inoculadas com L. monocytogenes cepa V7 e cepa VPH-1, e incubadas, aerobicamente, a 30ºC por 48 horas. Cada cepa foi testada individualmente, e determinou-se curvas de crescimento a 1, 2, 3, 4, 5, 21, 24, e 48 horas. O crescimento ou sobrevivência das duas cepas foi semelhante e encontrou-se sobreviventes em 24 horas de incubação. Examinou-se a atividade bactericida de um dos peptídeos catiônicos sintéticos (NP-2 contra L. monocytogenes cepa V7, em sistema aquoso. A atividade antibacteriana de NP-2 (1, 5, and 10µg/ml foi melhor aos 60 minutos de incubação, com 10µg/ml de peptídeo, a 30 C.

  5. CHALLENGE TESTS WITH LISTERIA MONOCYTOGENES IN SALAMI: PRELIMINARY RESULTS

    Directory of Open Access Journals (Sweden)

    R. Mioni

    2013-02-01

    Full Text Available Challenge tests are the preferable methodology to study the behaviour of Listeria monocytogenes on ready to eat foods, according to Regulation (EC 2073/2005. Challenge testing using L. monocytogenes in seasoned salami from different food business operators showed, after seasoning of the product, a count reduction of the inoculated organisms without any further growth of the pathogen; however differences of L. monocytogenes behaviour could be observed according to different production protocols.

  6. Internalization of Listeria monocytogenes in Whole Avocado.

    Science.gov (United States)

    Chen, Yi; Evans, Peter; Hammack, Thomas S; Brown, Eric W; Macarisin, Dumitru

    2016-08-01

    In recent years, tree fruits have emerged as a new concern for Listeria monocytogenes contamination. The objective of the current study was to evaluate the potential internalization of L. monocytogenes from the surface of avocados into the edible portions of the fruit during certain postharvest practices simulated in a laboratory setting. One set of intact avocados was spot inoculated with L. monocytogenes on the stem scar, and the second set was hydrocooled in water contaminated with L. monocytogenes. Under these experimental conditions, L. monocytogenes internalized into the avocado pulp through the stem or stem scar after both spot inoculation and hydrocooling. In avocados spot inoculated with 50, 130, 500, and 1,300 CFU per fruit, bacteria were detected in the edible portion adjacent to the stem scar within 15 days postinoculation during storage at 4°C. In avocados hydrocooled in water containing L. monocytogenes at 10(6) and 10(8) CFU/ml, bacteria reached the bottom end of the fruit, and the populations in the edible portion adjacent to the stem scar reached up to 5.90 to 7.19 log CFU/g within 10 to 15 days during storage at 4°C. Dye mixed with inoculum was useful for guiding subsequent sampling, but dye penetration patterns were not always consistent with bacterial penetration.

  7. Determination of Listeria monocytogenes Growth during Mushroom Production and Distribution

    Directory of Open Access Journals (Sweden)

    Dara Leong

    2013-11-01

    Full Text Available In the EU, food is considered safe with regard to Listeria monocytogenes if its numbers do not exceed 100 CFU/g throughout the shelf-life of the food. Therefore, it is important to determine if a food supports growth of L. monocytogenes. Challenge studies to determine the ability of a food to support growth of L. monocytogenes are essential as predictive modelling often overestimates the growth ability of L. monocytogenes. The aim of this study was to determine if growth of L. monocytogenes was supported during the production and distribution of mushrooms. A three-strain mixture of L. monocytogenes was inoculated onto three independent batches of whole mushrooms, sliced mushrooms, mushroom casing and mushroom substrate at a concentration of about 100–1000 CFU/g. The batches were incubated at potential abuse temperatures, as a worst case scenario, and at intervals during storage L. monocytogenes numbers, % moisture and pH were determined. The results showed that the sliced and whole mushrooms had the ability to support growth, while mushroom casing allowed survival but did not support growth. Mushroom substrate showed a rich background microflora that grew on Listeria selective media and this hindered enumeration of L. monocytogenes. In the case of this study, Combase predictions were not always accurate, indicating that challenge studies may be a necessary part of growth determination of L. monocytogenes.

  8. Determination of thermal inactivation kinetics of Listeria monocytogenes in chicken meat by isothermal and dynamic methods

    Science.gov (United States)

    The objective of this research is to determine the thermal inactivation kinetics of Listeria monocytogenes in chicken breast meat using both isothermal and dynamic conditions. A four-strain cocktail of L. monocytogenes was inoculated to chicken breast meat. Isothermal studies were performed by sub...

  9. Controlling attachment and growth of Listeria monocytogenes in polyvinyl chloride model floor drains using a peroxide chemical, chitosan-arginine, or heat.

    Science.gov (United States)

    Berrang, Mark E; Hofacre, Charles L; Frank, Joseph F

    2014-12-01

    Listeria monocytogenes can colonize a poultry processing plant as a resident in floor drains. Limiting growth and attachment to drain surfaces may help lessen the potential for cross-contamination of product. The objective of this study was to compare a hydrogen peroxide-peroxyacetic acid-based chemical to chitosan-arginine or heat to prevent attachment of or destroy existing L. monocytogenes on the inner surface of model floor drains. L. monocytogenes was introduced to result in about 10(9) planktonic and attached cells within untreated polyvinyl chloride model drain pipes. Treatments (0.13 % peroxide-based sanitizer, 0.1 % chitosan-arginine, or 15 s of hot water at 95 to 100°C) were applied immediately after inoculation or after 24 h of incubation. Following treatment, all pipes were incubated for an additional 24 h; planktonic and attached cells were enumerated by plate count. All treatments significantly (P < 0.05) lowered numbers of planktonic and attached cells recovered. Chitosan-arginine resulted in approximately a 6-log reduction in planktonic cells when applied prior to incubation and a 3-log reduction after the inoculum had a chance to grow. Both heat and peroxide significantly outperformed chitosan-arginine (8- to 9-log reduction) and were equally effective before and after incubation. Heat was the only treatment that eliminated planktonic L. monocytogenes. All treatments were less effective against attached cells. Chitosan-arginine provided about a 4.5-log decrease in attached cells when applied before incubation and no significant decrease when applied after growth. Like with planktonic cells, peroxide-peroxyacetic acid and heat were equally effective before or after incubation, causing decreases ranging from 7 to 8.5 log for attached L. monocytogenes. Applied at the most efficacious time, any of these techniques may lessen the potential for L. monocytogenes to remain as a long-term resident in processing plant floor drains.

  10. LISTERIA MONOCYTOGENES RISK EVALUATION IN READY TO EAT DELI PRODUCTS

    Directory of Open Access Journals (Sweden)

    T Civera

    2013-02-01

    Full Text Available Listeria monocytogenes has become one of the major concerns for food safety. Its ability to survive and replicate at low temperature, pH and high salt concentration, makes the bacterium a threat, mostly for RTE products. For these reasons, the present research was aimed at detecting the ability of growth of L. monocytogenes in RTE products retrieved from one deli store. Samples were analysed for L. monocytogenes detection, then inoculated with the pathogen (105cell/ml and stored at refrigeration temperature for the duration of their shelf-life (15-60 days. In all the products L. monocytogenes was not detected before experimental contamination. The challenge test evidenced that experimentally inoculated L. monocytogenes was not able to multiply for the duration of the entire shelf-life. These results indicated that the tested products could be considered as foods which are not able to support the growth of L. monocytogenes, as indicated by E.C. Regulation 2073/05. However, in order to guarantee consumer’s safety, it needs to be emphasized the need of a correct application of the GMPs, required for lowering the risk of initial contamination.

  11. Growth of Listeria monocytogenes in Salmon Roe - a kinetic analysis

    Science.gov (United States)

    The objective of this study was to investigate the growth kinetics of Listeria monocytogenes in unsalted and salted (3%) salmon roe. Growth curves, developed using inoculated samples incubated at constant temperatures between 5 and 30 degrees C, were analyzed by curve-fitting to the Huang and Baran...

  12. Lactobacillus plantarum inhibits growth of Listeria monocytogenes in an in vitro continuous flow gut model, but promotes invasion of L. monocytogenes in the gut of gnotobiotic rats

    DEFF Research Database (Denmark)

    Bernbom, Nete; Licht, Tine Rask; Saadbye, Peter;

    2006-01-01

    The ability of the pediocin AcH producing Lactobacillus plantarum DDEN 11007 and its non-producing plasmid-cured isogenic variant, DDEN 12305 to prevent the persistence and growth of Listeria monocytogenes EP2 in two gastrointestinal (GI) tract models was examined. In vitro studies conducted...... in a two-stage continuous flow system showed that L. plantarum DDEN 11007 inhibited L. monocytogenes EP2 under these conditions, while less effect was seen of the non-bacteriocin producing variant. The inhibitory effect was more pronounced at pH 5 than at pH 7. No effect on persistence of L. monocytogenes...... in the GI tract was seen in gnotobiotic rats colonized with either the pediocin AcH producing or the non-bacteriocin producing variant of L. plantarum when compared to rats inoculated with L. monocytogenes EP2 alone. Surprisingly, inoculation of the gnotobiotic animals with either of the L. plantarum...

  13. Effect of a bacteriophage cocktail in combination with modified atmosphere packaging in controlling Listeria monocytogenes on fresh-cut spinach

    Directory of Open Access Journals (Sweden)

    Boyacioglu O.

    2016-06-01

    Full Text Available A Listeria monocytogenes-specific bacteriophage cocktail was evaluated for its activity against a nalidixic acid-resistant L. monocytogenes (Lm-NalR isolate on fresh-cut spinach stored under modified atmosphere packaging at various temperatures. Pieces (~2 × 2 cm2 of fresh spinach inoculated with 4.5 log CFU/cm2 Lm-NalR were sprayed with the phage cocktail (6.5 log plaque-forming units [PFU]/cm2 or a control. The samples were stored at 4°C or 10°C for up to 14 d in sealed packages filled with either atmospheric air (AA or modified atmosphere (MA. At 4°C under AA, the phages significantly (P ≤ 0.05 lowered the Lm-NalR populations on spinach, compared to control-treated inoculated samples, by 1.12 and 1.51 log CFU/cm2 after 1 and 14 d, respectively. At 4°C under MA, Lm-NalR was significantly reduced by 1.95 log CFU/cm2 compared to control leaves after both 1 and 14 d. At 10°C under AA, the phages significantly reduced Lm-NalR by 1.50 and 2.51 log CFU/cm2 after 1 and 14 d compared to the control. Again at 10°C under MA, the phages significantly reduced Lm-NalR by 1.71 and 3.24 log CFU/cm2 compared to control after 1 and 14 d, respectively. The results support the potential of lytic bacteriophages in effectively reducing populations of L. monocytogenes on freshcut leafy produce, under both AA and MA conditions.

  14. Animal models for oral transmission of Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Sarah E F D'Orazio

    2014-02-01

    Full Text Available Listeria monocytogenes has been recognized as a food borne pathogen in humans since the 1980s, but we still understand very little about oral transmission of L. monocytogenes or the host factors that determine susceptibility to gastrointestinal infection, due to the lack of an appropriate small animal model of oral listeriosis. Early feeding trials suggested that many animals were highly resistant to oral infection, and the more reproducible intravenous or intraperitoneal routes of inoculation soon came to be favored. There are a fair number of previously published studies using an oral infection route, but the work varies widely in terms of bacterial strain choice, the methods used for oral transmission, and various manipulations used to enhance infectivity. This mini review will summarize the published literature using oral routes of L. monocytogenes infection and will highlight recent technological advances that have made oral infection a more attractive model system.

  15. Effect of Listeria monocytogenes inoculation, sodium acetate and ...

    African Journals Online (AJOL)

    Jane

    2011-08-08

    Aug 8, 2011 ... This pathogen is able to survive in a wide range of temperature, pH and NaCl concentration. In refrigerated stored meat ... stomacher (stomacher 400 Lab Blender, Seward Medical, UK) ..... Packaging Technol. Sci., 15: 241- ...

  16. Survival and Metabolic Activity of Listeria monocytogenes on Ready-to-Eat Roast Beef Stored at 4 °C.

    Science.gov (United States)

    Broady, Johnathan W; Han, Dong; Yuan, Jing; Liao, Chao; Bratcher, Christy L; Lilies, Mark R; Schwartz, Elizabeth H; Wang, Luxin

    2016-07-01

    Three brands of commercial roast beef were purchased and artificially inoculated with a 5-strain Listeria monocytogenes cocktail at 2 inoculation levels (approximately 3 and 6 Log CFU/g). Although all 3 brands contained sodium diacetate and sodium lactate, inoculated Listeria cocktail survived for 16 d in all 3 brands; significant increases in L. monocytogenes numbers were seen on inoculated Brand B roast beef on days 12 and 16. Numbers of L. monocytogenes increased to 4.14 Log CFU/g for the 3 Log CFU/g inoculation level and increased to 7.99 Log CFU/g for the 6 Log CFU/g inoculation level by day 16, with the pH values being 5.4 and 5.8 respectively. To measure the cell viability in potential biofilms formed, an Alamar blue assay was conducted. Brand B meat homogenate had the highest metabolic activities (P monocytogenes in ready-to-eat roast beef. Native microflora (both diversity and abundance), together with product formula, pH, antimicrobial concentrations, and storage conditions may all impact the survival and growth of L. monocytogenes. © 2016 Institute of Food Technologists®

  17. Modeling the growth of Listeria monocytogenes on cut cantaloupe, honeydew and watermelon.

    Science.gov (United States)

    Danyluk, Michelle D; Friedrich, Loretta M; Schaffner, Donald W

    2014-04-01

    A recent outbreak linked to whole cantaloupes underscores the importance of understanding growth kinetics of Listeria monocytogenes in cut melons at different temperatures. Whole cantaloupe, watermelon, and honeydew purchased from a local supermarket were cut into 10 ± 1 g cubes. A four-strain cocktail of L. monocytogenes from food related outbreaks was used to inoculate fruit, resulting in ~10(3) CFU/10 g. Samples were stored at 4, 10, 15, 20, or 25 °C and L. monocytogenes were enumerated at appropriate time intervals. The square root model was used to describe L. monocytogenes growth rate as a function of temperature. The model was compared to prior models for Salmonella and Escherichia coli O157:H7 growth on cut melon, as well as models for L. monocytogenes on cantaloupe and L. monocytogenes ComBase models. The current model predicts faster growth of L. monocytogenes vs. Salmonella and E. coli O157:H7 at temperatures below 20 °C, and agrees with estimates from ComBase Predictor, and a corrected published model for L. monocytogenes on cut cantaloupe. The model predicts ~4 log CFU increase following 15 days at 5 °C, and ∼1 log CFU increase following 6 days at 4 °C. The model can also be used in subsequent quantitative microbial risk assessments.

  18. Loss of viability of Listeria monocytogenes in contaminated processed cheese during storage at 4, 12 and 22 degrees C.

    Science.gov (United States)

    Angelidis, Apostolos S; Boutsiouki, Paraskevi; Papageorgiou, Demetrios K

    2010-09-01

    The behaviour of Listeria monocytogenes in a processed cheese product was evaluated over time by inoculating the product with three different L. monocytogenes strains (Scott A, CA and a strain isolated from processed cheese) at three different inoculation levels (ca. 6x10(5), ca. 6x10(3) and 10(2)CFU/g of cheese or less) and after storage of the contaminated products at 4, 12 or 22 degrees C. Growth of L. monocytogenes was not observed in any of the experimental trials (experiments involving different combinations of strain, inoculum level and storage temperature) throughout the storage period. L. monocytogenes populations decreased over time with a rate that was strain- and storage temperature-dependent. Nonetheless, for cheeses that had been inoculated with the higher inoculum and stored at 4 degrees C viable populations of L. monocytogenes could be detected for up to nine months post-inoculation. The L. monocytogenes survival curves obtained from the different trials were characterised by a post-inoculation phase during which the populations remained essentially unchanged (lag phase) followed by a phase of logarithmic decline. The duration of the lag phase and the rate of inactivation of L. monocytogenes in the different trials were estimated based on data from the linear descending portions of the survival curves. In addition, a non-linear Weibull-type equation was fitted to the data from each survival curve with satisfactory results. The results of the present study emphasize that, according to the definition laid down in the European Union Regulation 1441/2007, the processed cheese product tested in this work should be considered and classified as one that does not support the growth of L. monocytogenes under reasonable foreseeable conditions of distribution and storage. However, post-processing contamination of the product should be austerely avoided as the pathogen can survive in the product for extended periods of time, particularly under refrigerated

  19. Growth kinetics of Listeria monocytogenes and spoilage microorganisms in fresh-cut cantaloupe.

    Science.gov (United States)

    Fang, Ting; Liu, Yanhong; Huang, Lihan

    2013-05-01

    The main objective of this study was to investigate the growth kinetics of Listeria monocytogenes and background microorganisms in fresh-cut cantaloupe. Fresh-cut cantaloupe samples, inoculated with three main serotypes (1/2a, 1/2b, and 4b) of L. monocytogenes, were incubated at different temperatures, ranging from 4 to 43 °C, to develop kinetic growth models. During storage studies, the population of both background microorganisms and L. monocytogenes began to increase almost immediately, with little or no lag phase for most growth curves. All growth curves, except for two growth curves of L. monocytogenes 1/2a at 4 °C, developed to full curves (containing exponential and stationary phases), and can be described by a 3-parameter logistic model. There was no significant difference (P = 0.28) in the growth behaviors and the specific growth rates of three different serotypes of L. monocytogenes inoculated to fresh-cut cantaloupe. The effect of temperature on the growth of L. monocytogenes and spoilage microorganisms was evaluated using three secondary models. For L. monocytogenes, the minimum and maximum growth temperatures were estimated by both the Ratkowsky square-root and Cardinal parameter models, and the optimum temperature and the optimum specific growth rate by the Cardinal parameter model. An Arrhenius-type model provided more accurate estimation of the specific growth rate of L. monocytogenes at temperatures <4 °C. The kinetic models developed in this study can be used by regulatory agencies and food processors for conducting risk assessment of L. monocytogenes in fresh-cut cantaloupe, and for estimating the shelf-life of fresh-cut products.

  20. Listeria monocytogenes: diagnostic problems

    NARCIS (Netherlands)

    Beumer, R.R.; Hazeleger, W.C.

    2003-01-01

    The first isolation methods for the detection of Listeria spp. were generally based on the direct culture of samples on simple agar media, but isolation of the pathogenic Listeria monocytogenes was difficult. In time, new techniques were developed, based on a variety of selective and elective agents

  1. Listeria monocytogenes endocarditis.

    Science.gov (United States)

    Sheinman, B D; Evans, T; Sage, R

    1985-01-01

    A fatal case of endocarditis due to Listeria monocytogenes is reported. Case reports of endocarditis due to this organism are rare but indicate a higher mortality than with many other causes of bacterial endocarditis. The size of the problem may be underestimated because the organism has a "diphtheroid' appearance and may be incorrectly dismissed as a contaminant.

  2. Mathematical modelling of growth of Listeria  monocytogenes in raw chilled pork.

    Science.gov (United States)

    Ye, K; Wang, K; Liu, M; Liu, J; Zhu, L; Zhou, G

    2017-04-01

    The aim of this study was to analyse the growth kinetics of Listeria monocytogenes in naturally contaminated chilled pork. A cocktail of 26 meat-borne L. monocytogenes was inoculated to raw or sterile chilled pork to observe its growth at 4, 10, 16, 22 and 28°C respectively. The growth data were fitted by the Baranyi model and Ratkowsky square-root model. Results showed that the Baranyi model and Ratkowsky square-root model could describe the growth characteristics of L. monocytogenes at different temperatures reasonably well in raw chilled pork (1·0 ≤ Bf ≤ Af ≤ 1·1). Compared with the growth of L. monocytogenes in sterile chilled pork, the background microflora had no impact on the growth parameters of L. monocytogenes, except for the lag phase at low temperature storage. The microbial predictive models developed in this study can be used to predict the growth of L. monocytogenes during natural spoilage, and construct quantitative risk assessments in chilled pork. This study simulated the actual growth of Listeria monocytogenes in chilled pork to the maximum extent, and described its growth characteristics of L. monocytogenes during natural spoilage. This study showed that the background microflora had no impact on the growth parameters of L. monocytogenes, except for the lag phase at low temperature storage. The models developed in this study can be used to predict the growth of L. monocytogenes during refrigerated storage. © 2017 The Society for Applied Microbiology.

  3. Evaluation of Listeria monocytogenes survival in ice cream mixes flavored with herbal tea using Taguchi method.

    Science.gov (United States)

    Ozturk, Ismet; Golec, Adem; Karaman, Safa; Sagdic, Osman; Kayacier, Ahmed

    2010-10-01

    In this study, the effects of the incorporation of some herbal teas at different concentrations into the ice cream mix on the population of Listeria monocytogenes were studied using Taguchi method. The ice cream mix samples flavored with herbal teas were prepared using green tea and sage at different concentrations. Afterward, fresh culture of L. monocytogenes was inoculated into the samples and the L. monocytogenes was counted at different storage periods. Taguchi method was used for experimental design and analysis. In addition, some physicochemical properties of samples were examined. Results suggested that there was some effect, although little, on the population of L. monocytogenes when herbal tea was incorporated into the ice cream mix. Additionally, the use of herbal tea caused a decrease in the pH values of the samples and significant changes in the color values.

  4. Thermal inactivation of Listeria monocytogenes and Salmonella spp. in sous-vide processed marinated chicken breast

    Science.gov (United States)

    The heat resistance of a cocktail of five Salmonella strains and five L. monocytogenes strains was determined in teriyaki-marinated chicken breasts. Inoculated meat, packaged in bags, were completely immersed in a circulating water bath and cooked to a final temperature of 55, 57.5 or 60C in one h...

  5. QUANTIFICATION OF LISTERIA MONOCYTOGENES IN MILK BY MPN-PCR AND MPN-CULTURE METHODS

    Directory of Open Access Journals (Sweden)

    Mahzad Hosseini

    2014-10-01

    Full Text Available The aim of this study was to compare the MPN-PCR (Most Probable Number- Polymerase Chain Reaction and MPN-Culture methods in enumerating of Listeria monocytogenes in milk. In order to compare the accuracy of these methods, 103 cell/ml Listeria monocytogenes and different background bacteria which may be present in raw milk, were inoculated in sterilized milk. After preparing serial dilutions, three replicates per dilution were inoculated in tubes containing listeria enrichment broth. After 48 hours of incubation, for MPN-Culture three inoculated replicates were subcultured on Oxford agar and suspected colonies were confirmed by performing by biochemical tests. For MPN-PCR assay, the DNA extraction was performed from the three inoculated replicates which were already used for MPN-Culture and PCR assay was performed using primers specific for Listeria monocytogenes. The experiment was repeated three times and the average of enumerated bacteria was calculated by each method separately. Statistical analysis using one sample Wilcoxon signed rank test showed that enumeration by MPN-PCR method was more accurate than enumeration by MPN-Culture method. The result of this study showed that MPN-PCR method in comparision with MPN-Culture even in the presence of different background microorganisms is more rapid and reliable. It is concluded that MPN-PCR method facilitates the enumeration of Listeria monocytogenes without excessive work and could be considered as an alternative to MPN-Culture technique.

  6. Control of Listeria monocytogenes in turkey deli loaves using organic acids as formulation ingredients.

    Science.gov (United States)

    Lloyd, T; Alvarado, C Z; Brashears, M M; Thompson, L D; McKee, S R; Berrang, M

    2009-10-01

    The growth of Listeria monocytogenes in further-processed meat products has become a major concern and an important food safety issue. The meat and poultry industries have incorporated interventions such as organic acids in marinades to inhibit the growth of L. monocytogenes. In this study, organic acids were utilized in the raw product and as a postcook dip to determine their inhibitory effect on the growth of L. monocytogenes in turkey deli loaves. The turkey deli loaves were processed, cooked, cooled, inoculated with streptomycin-resistant L. monocytogenes, and then dipped. Treatments were potassium lactate (PL) in the raw product with sodium lactate (SL), sodium diacetate (SD) dip, PL with SL/PL/SD dip, SL with SL/SD dip, and SL with SL/PL/SD dip. There was also a positive (inoculated) and negative (noninoculated) control, which was dipped in distilled water. Days 0, 7, 14, 21, 28, 42, and 56 were sampled for L. monocytogenes. There were no differences (P>0.05) among the organic acid treatments in the turkey deli loaves at any time points; therefore, all of the treatments increased the lag phase of L. monocytogenes, extending the shelf-life of the product. However, there was a difference between the treatments and the positive control at d 7, 14, 21, 28, 42, and 56. The growth of L. monocytogenes increased immediately in the positive control, whereas the negative control appeared to have no growth. These organic acids can provide meat processors with a useful method for extending the lag phase of L. monocytogenes in ready-to-eat meat and poultry products.

  7. Evaluation of Three Swabbing Devices for Detection of Listeria monocytogenes on Different Types of Food Contact Surfaces

    Directory of Open Access Journals (Sweden)

    Evy Lahou

    2014-01-01

    Full Text Available Listeria monocytogenes can adhere to different types of food contact surfaces within a food processing environment. Therefore, environmental sampling devices should be capable of detecting unacceptable contamination. In this study, a sponge-stick, foam spatula and an environmental swab were evaluated on their ability to detect low concentrations of L. monocytogenes on different types of food contact surfaces. A cocktail of four L. monocytogenes serotypes was inoculated with a concentration of 100 CFU/250 cm2 onto stainless steel (SS, high density polyethylene (HDPE and rubber surfaces in a 250 cm2 area. Immediately after inoculation and after 1 h exposure, the surfaces were swabbed with the different swabbing devices. The results of the study show only minor differences in the ability of the swabbing devices to detect L. monocytogenes. All devices were capable to detect the contamination immediately after inoculation. However, when the surfaces were allowed to air-dry for 1 h, L. monocytogenes was undetected in 11.1% of the samples (n = 27 with the sponge stick, in 7.4% of the samples (n = 27 with the foam spatula and in 3.7% of the samples (n = 27 with the environmental swab, especially on SS surfaces. The detection ability of the different devices for L. monocytogenes can be concluded to be rather high on different types of food contact surfaces.

  8. Effect of Listeria seeligeri or Listeria welshimeri on Listeria monocytogenes detection in and recovery from buffered Listeria enrichment broth.

    Science.gov (United States)

    Dailey, Rachel C; Welch, Lacinda J; Hitchins, Anthony D; Smiley, R Derike

    2015-04-01

    The presence of multiple species of Listeria in regulated food products is not uncommon and can complicate the recovery of Listeria monocytogenes particularly on a non-differentiating medium. The potential complications of Listeria seeligeri and Listeria welshimeri on the recovery of L. monocytogenes from inoculated food test samples using the U.S. Food and Drug Administration's (FDA) selective enrichment procedure was investigated. Post-enrichment enumeration, in the absence of food product, indicates that some L. seeligeri and L. monocytogenes pairings may have population differentials as great as 2.7 ± 0.1 logs with L. seeligeri being the predominant species. A similar observation was noted for L. welshimeri and L. monocytogenes pairings which resulted in population differentials as large as 3.7 ± 0.2 logs with L. welshimeri being the predominant species. Select strain pairings were used to inoculate guacamole, crab meat, broccoli, and cheese with subsequent recovery by the FDA Bacteriological Analytical Manual (BAM) method with 10 colonies per sample selected for confirmation. The presence of L. seeligeri had little effect on the recovery of L. monocytogenes. The presence of L. welshimeri resulted in the failure to recover L. monocytogenes in three out of the four food matrices. This work extends the observation that non-pathogenic species of Listeria can complicate the recovery of L. monocytogenes and that competition during selective enrichment is not limited to the presence of just Listeria innocua. Published by Elsevier Ltd.

  9. Effect of Listeria seeligeri or Listeria welshimeri on Listeria monocytogenes detection in and recovery from buffered Listeria enrichment broth☆

    Science.gov (United States)

    Dailey, Rachel C.; Welch, Lacinda J.; Hitchins, Anthony D.; Smiley, R. Derike

    2016-01-01

    The presence of multiple species of Listeria in regulated food products is not uncommon and can complicate the recovery of Listeria monocytogenes particularly on a non-differentiating medium. The potential complications of Listeria seeligeri and Listeria welshimeri on the recovery of L. monocytogenes from inoculated food test samples using the U.S. Food and Drug Administration's (FDA) selective enrichment procedure was investigated. Post-enrichment enumeration, in the absence of food product, indicates that some L. seeligeri and L. monocytogenes pairings may have population differentials as great as 2.7 ± 0.1 logs with L. seeligeri being the predominant species. A similar observation was noted for L. welshimeri and L. monocytogenes pairings which resulted in population differentials as large as 3.7 ± 0.2 logs with L. welshimeri being the predominant species. Select strain pairings were used to inoculate guacamole, crab meat, broccoli, and cheese with subsequent recovery by the FDA Bacteriological Analytical Manual (BAM) method with 10 colonies per sample selected for confirmation. The presence of L. seeligeri had little effect on the recovery of L. monocytogenes. The presence of L. welshimeri resulted in the failure to recover L. monocytogenes in three out of the four food matrices. This work extends the observation that non-pathogenic species of Listeria can complicate the recovery of L. monocytogenes and that competition during selective enrichment is not limited to the presence of just Listeria innocua. PMID:25475325

  10. EFFECTIVENESS OF ELECTROLYZED OXIDIZING WATER FOR INACTIVATING Listeria monocytogenes IN LETTUCE

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    Casadiego Laíd Paola

    2005-06-01

    Full Text Available The effectiveness of electrolyzed oxidizing (EO water for the inactivation of L. monocytogenes in suspension and when inoculated on lettuce leaves was evaluated. An electrolytic cell for the production of EO water was built and a solution of 5% NaCl was used. The EO water produced had a residual chlorine concentration of 29 parts per million (ppm and pH 2.83. Ten strains of L. monocytogenes isolated from processed chicken (109 CFU/ml were inoculated into 9 ml of EO water or 9 ml of deionized water (control and incubated at 15°C for 5, 10, 15 and 20 min. The surviving population of each strain was determined on Columbia agar. An exposure time of 5 min reduced the populations by approximately 6.6 log CFU/ml. The most resistant strains to sodium hypochlorite (NaOCl were selected and used in a strain mixture (9.56 log CFU/ml, 109UFC/ml approximately for the inoculation of 35 lettuce samples, by the dip inoculation method using distilled water as control. The population mean of L. monocytogenes after treatment with EO water and distilled water was reduced by 3.92 and 2.46 log CFU/ml respectively (p=0.00001. EO water and 6% acetic acid (vinegar were combined to improve the EO water effect on L. monocytogenes inoculated in lettuce; the effectiveness of this combination was examined. The results showed that there was a synergistic effect of both antimicrobial agents (population reduction by 5.49 log CFU/ml approximately on the viability of L. monocytogenes cells.

  11. Biotic and abiotic soil properties influence survival of Listeria monocytogenes in soil.

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    Aude Locatelli

    Full Text Available Listeria monocytogenes is a food-borne pathogen responsible for the potentially fatal disease listeriosis and terrestrial ecosystems have been hypothesized to be its natural reservoir. Therefore, identifying the key edaphic factors that influence its survival in soil is critical. We measured the survival of L. monocytogenes in a set of 100 soil samples belonging to the French Soil Quality Monitoring Network. This soil collection is meant to be representative of the pedology and land use of the whole French territory. The population of L. monocytogenes in inoculated microcosms was enumerated by plate count after 7, 14 and 84 days of incubation. Analysis of survival profiles showed that L. monocytogenes was able to survive up to 84 days in 71% of the soils tested, in the other soils (29% only a short-term survival (up to 7 to 14 days was observed. Using variance partitioning techniques, we showed that about 65% of the short-term survival ratio of L. monocytogenes in soils was explained by the soil chemical properties, amongst which the basic cation saturation ratio seems to be the main driver. On the other hand, while explaining a lower amount of survival ratio variance (11%, soil texture and especially clay content was the main driver of long-term survival of L. monocytogenes in soils. In order to assess the effect of the endogenous soils microbiota on L. monocytogenes survival, sterilized versus non-sterilized soils microcosms were compared in a subset of 9 soils. We found that the endogenous soil microbiota could limit L. monocytogenes survival especially when soil pH was greater than 7, whereas in acidic soils, survival ratios in sterilized and unsterilized microcosms were not statistically different. These results point out the critical role played by both the endogenous microbiota and the soil physic-chemical properties in determining the survival of L. monocytogenes in soils.

  12. A note on challenge trials to determine the growth of Listeria monocytogenes on mushrooms (Agaricus bisporus

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    Leong Dara

    2015-12-01

    Full Text Available In the EU, food is considered safe with regard to Listeria monocytogenes if the number of micro-organisms does not exceed 100 colony forming units (cfu/g throughout its shelf-life. Therefore, it is important to determine if a food supports growth of L. monocytogenes. Guidelines for conducting challenge tests for growth assessment of L. monocytogenes on foods were published by the European Union Reference Laboratory (EURL in 2014. The aim of this study was to use these guidelines to determine if refrigerated, fresh, whole, closed-cap, prepackaged mushrooms (Agaricus bisporus support the growth of L. monocytogenes. Three batches of mushrooms were artificially inoculated at approximately 100 cfu/g with a three-strain mix of L. monocytogenes and incubated for 2 days at 8°C followed by 4 days at 12°C. L. monocytogenes numbers were determined (in triplicate for each batch on days 0, 2 and 6. Water activity, pH and total bacterial counts were also determined. There was no increase in the number of L. monocytogenes above the threshold of 0.5 log cfu/g in any of the replicates. In 8 of 9 replicates, the numbers decreased indicating that A. bisporus do not support the growth of L. monocytogenes. As the EU regulations allow < 100 cfu/g if the food cannot support growth of L. monocytogenes, the significance of this study is that mushrooms with < 100 cfu/g may be within the regulations and therefore, quantitative rather than qualitative determination may be required.

  13. Effects of essential oil from mint (Mentha piperita) on Salmonella enteritidis and Listeria monocytogenes in model food systems at 4 degrees and 10 degrees C.

    Science.gov (United States)

    Tassou, C C; Drosinos, E H; Nychas, G J

    1995-06-01

    The effect of mint (Mentha piperita) essential oil (0.5, 1.0, 1.5 and 2.0%, v/w) on Salmonella enteritidis and Listeria monocytogenes in a culture medium and three model foods; tzatziki (pH 4.5), taramosalata (pH 5.0) and pâté (pH 6.8), inoculated at 10(7) cfu g-1, at 4 degrees and 10 degrees C for ca 1 week was studied. In the culture medium supplemented with the essential oil, no growth was observed over 2 d at 30 degrees C determined by a conductance method with a Malthus 2000 growth analyser. Salmonella enteritidis died in tzatziki in all treatments and declined in the other foods except for pâté at 10 degrees C as judged with viable counts. Listeria monocytogenes populations showed a declining trend towards the end of the storage period but was increased in pâté. Mint essential oil antibacterial action depended mainly on its concentration, food pH, composition, storage temperature and the nature of the micro-organism.

  14. Viability of Listeria monocytogenes on Boneless, Water-Added Hams, Commercially Prepared with and without Food-Grade Chemicals, during Extended Storage at 4 and/or -2.2°C.

    Science.gov (United States)

    Luchansky, John B; Campano, Stephen G; Shoyer, Bradley A; Porto-Fett, Anna C S

    2016-04-01

    Viability of Listeria monocytogenes was monitored during refrigerated (4°C) and/or frozen (i.e., deep chilling at -2.2°C) storage on casing-cooked hams that were commercially prepared with and without potassium lactate and sodium diacetate (1.6%), buffered vinegar (2.2%), buffered vinegar and potassium lactate (1.7%), or a blend of potassium lactate, potassium acetate, and sodium diacetate (1.7%). A portion of these hams were subsequently surface treated with lauric arginate ester (LAE; 44 ppm). In phase I, hams (ca. 3.5 kg each) were sliced (ca. 0.7 cm thick, ca. 100 g), inoculated (ca. 4.0 log CFU per slice), surface treated with LAE, and stored at either 4°C for 120 days or at -2.2°C for 90 days and then at 4°C for an additional 120 days. In phase I, without antimicrobials, the population of L. monocytogenes increased by ca. 5.9 log CFU per slice within 120 days at 4°C; however, pathogen levels increased only slightly (ca. 0.45 log CFU per slice) for hams formulated with potassium lactate and sodium diacetate and decreased by ca. 1.2 log CFU per slice when formulated with the other antimicrobials. For slices held at -2.2°C and then stored at 4°C, but not treated with LAE, L. monocytogenes increased by ca. 4.5 log CFU per slice for controls, whereas when formulated with antimicrobials, pathogen levels decreased by ca. 1.4 to 1.8 log CFU per slice. For product treated with LAE, L. monocytogenes increased by ca. 4.0 log CFU per slice for controls, whereas when formulated with antimicrobials, pathogen levels decreased by ca. 0.9 to 1.9 log CFU per slice. In phase II, whole hams (ca. 1.0 kg each) containing antimicrobials were inoculated (6.8 log CFU per ham) and then stored at -2.2°C for 6 months. Pathogen levels decreased by ca. 2.0 to 3.5 log CFU per ham (without LAE treatment) and by ca. 4.2 to 5.2 log CFU per ham (with application of LAE via Sprayed Lethality in Container) when product was held at -2.2°C. In general, deep chilling hams was listericidal

  15. Phosphatidylinositol 5-phosphatase oculocerebrorenal syndrome of Lowe protein (OCRL) controls actin dynamics during early steps of Listeria monocytogenes infection.

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    Kühbacher, Andreas; Dambournet, Daphné; Echard, Arnaud; Cossart, Pascale; Pizarro-Cerdá, Javier

    2012-04-13

    Listeria monocytogenes is a bacterial pathogen that induces its own entry into a broad range of mammalian cells through interaction of the bacterial surface protein InlB with the cellular receptor Met, promoting an actin polymerization/depolymerization process that leads to pathogen engulfment. Phosphatidylinositol bisphosphate (PI[4,5]P(2)) and trisphosphate (PI[3,4,5]P(3)) are two major phosphoinositide species that function as molecular scaffolds, recruiting cellular effectors that regulate actin dynamics during L. monocytogenes infection. Because the phosphatidylinositol 5'-phosphatase OCRL dephosphorylates PI(4,5)P(2) and to a lesser extent PI(3,4,5)P(3), we investigated whether this phosphatase modulates cell invasion by L. monocytogenes. Inactivation of OCRL by small interfering RNA (siRNA) leads to an increase in the internalization levels of L. monocytogenes in HeLa cells. Interestingly, OCRL depletion does not increase but rather decreases the surface expression of the receptor Met, suggesting that OCRL controls bacterial internalization by modulating signaling cascades downstream of Met. Immuno-fluorescence microscopy reveals that endogenous and overexpressed OCRL are present at L. monocytogenes invasion foci; live-cell imaging additionally shows that actin depolymerization coincides with EGFP-OCRL-a accumulation around invading bacteria. Together, these observations suggest that OCRL promotes actin depolymerization during L. monocytogenes infection; in agreement with this hypothesis, OCRL depletion leads to an increase in actin, PI(4,5)P(2), and PI(3,4,5)P(3) levels at bacterial internalization foci. Furthermore, in cells knocked down for OCRL, transfection of enzymatically active EGFP-OCRL-a (but not of a phosphatase-dead enzyme) decreases the levels of intracellular L. monocytogenes and of actin associated with invading bacteria. These results demonstrate that through its phosphatase activity, OCRL restricts L. monocytogenes invasion by modulating

  16. Cross-contamination between processing equipment and deli meats by Listeria monocytogenes.

    Science.gov (United States)

    Lin, Chia-Min; Takeuchi, Kazue; Zhang, Lei; Dohm, Cynthia B; Meyer, Joseph D; Hall, Paul A; Doyle, Michael P

    2006-01-01

    Contamination of luncheon meats by Listeria monocytogenes has resulted in outbreaks of listeriosis and major product recalls. Listeriae can survive on processing equipment such as meat slicers which serve as a potential contamination source. This study was conducted to determine (i) the dynamics of cross-contamination of L. monocytogenes from a commercial slicer and associated equipment onto sliced meat products, (ii) the influence of sample size on the efficacy of the BAX-PCR and U.S. Department of Agriculture-Food Safety and Inspection Service enrichment culture assays to detect L. monocytogenes on deli meat, and (iii) the fate of L. monocytogenes on sliced deli meats of different types during refrigerated storage. Three types of deli meats, uncured oven-roasted turkey, salami, and bologna containing sodium diacetate and potassium lactate, were tested. A five-strain mixture of L. monocytogenes was inoculated at ca.10(3) CFU onto the blade of a commercial slicer. Five consecutive meat slices were packed per package, then vacuum sealed, stored at 4 degrees C, and sampled at 1 and 30 days postslicing. Two sample sizes, 25 g and contents of the entire package of meat, were assayed. Total numbers of L. monocytogenes-positive samples, including the two sample sizes and two sampling times, were 80, 9, and 3 for turkey, salami, and bologna, respectively. A higher percentage of turkey meat samples were L. monocytogenes positive when contents of the entire package were assayed than when the 25-g sample was assayed (12.5 and 7.5%, respectively). Lower inoculum populations of ca. 10(1) or 10(2) CFU of L. monocytogenes on the slicer blade were used for an additional evaluation of oven-roasted turkey using two additional sampling times of 60 and 90 days postslicing. L. monocytogenes-positive samples were not detected until 60 days postslicing, and more positive samples were detected at 90 days than at 60 days postslicing. When BAX-PCR and enrichment culture assays were

  17. High-pressure processing of Gorgonzola cheese: influence on Listeria monocytogenes inactivation and on sensory characteristics.

    Science.gov (United States)

    Carminati, D; Gatti, M; Bonvini, B; Neviani, E; Mucchetti, G

    2004-08-01

    The presence of Listeria monocytogenes on the rind of Gorgonzola cheese is difficult to avoid. This contamination can easily occur as a consequence of handling during ripening. The aims of this study were to determine the efficiency of high-pressure processing (HPP) for inactivation of L. monocytogenes on cheese rind and to evaluate the influence of HPP treatments on sensory characteristics. Gorgonzola cheese rinds, after removal, were inoculated (about 7.0 log CFU/g) with L. monocytogenes strains previously isolated from other Gorgonzola cheeses. The inoculated cheese rinds were processed with an HPP apparatus under conditions of pressure and time ranging from 400 to 700 MPa for 1 to 15 min. Pressures higher than 600 MPa for 10 min or 700 MPa for 5 min reduced L. monocytogenes more than 99%. A reduction higher than 99.999% was achieved pressurizing cheese rinds at 700 MPa for 15 min. Lower pressure or time treatments were less effective and varied in effectiveness with the cheese sample. Changes in sensory properties possibly induced by the HPP were evaluated on four different Gorgonzola cheeses. A panel of 18 members judged the treated and untreated cheeses in a triangle test. Only one of the four pressurized cheeses was evaluated as different from the untreated sample. HPP was effective in the reduction of L. monocytogenes on Gorgonzola cheese rinds without significantly changing its sensory properties. High-pressure technology is a useful tool to improve the safety of this type of cheese.

  18. [Listeria monocytogenes in food].

    Science.gov (United States)

    Mícková, V

    1992-12-01

    As in recent years laboratory diagnostics of listeria has become part of food microbiology, the frequency of occurrence of the bacteria Listeria monocytogenes has been followed in various kinds of foods for a year. A total of 51 strains of L. monocytogenes (7.2%) was isolated from 700 kinds of samples (raw milk, pasteurized milk, meat surface, poultry, cheeses, thermally not treated meat products, food--industry machinery). As can be seen in Tab. I, the highest number of strains was isolated from meat surfaces (13.5%), followed by meat--industry machinery (12.72%), poultry (10%) and cheeses (5%). The lower numbers of strains were found out in thermally not treated meat products (3.8%) and in raw milk (3.3%). Pasteurized milk did not contain any strains. Our findings in raw milk (3.3%) and in pasteurized milk (0) are in agreement with the data cited e. g. by authors from the USA (Lovett et al., 1987), who mention the value of 4.2% in raw milk and the zero value in pasteurized milk. The percentage of strains monitored in cheeses (5%) can be evaluated as low as the assortment of investigated cheeses was small (all strains were isolated from soft ripening cheeses). German authors (Tham et al., 1988) speak about the 2.5% percentage of L. monocytogenes strains; this is in keeping with our findings. The findings in thermally not treated meat products (3.8%) can be evaluated as low although the number of strains found in raw meat was high.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Fat content increases the lethality of ultra-high-pressure homogenization on Listeria monocytogenes in milk.

    Science.gov (United States)

    Roig-Sagués, A X; Velázquez, R M; Montealegre-Agramont, P; López-Pedemonte, T J; Briñez-Zambrano, W J; Guamis-López, B; Hernandez-Herrero, M M

    2009-11-01

    Listeria monocytogenes CCUG 15526 was inoculated at a concentration of approximately 7.0 log(10) cfu/mL in milk samples with 0.3, 3.6, 10, and 15% fat contents. Milk samples with 0.3 and 3.6% fat content were also inoculated with a lower load of approximately 3.0 log(10) cfu/mL. Inoculated milk samples were subjected to a single cycle of ultra-high-pressure homogenization (UHPH) treatment at 200, 300, and 400 MPa. Microbiological analyses were performed 2 h after the UHPH treatments and after 5, 8, and 15 d of storage at 4 degrees C. Maximum lethality values were observed in samples treated at 400 MPa with 15 and 10% fat (7.95 and 7.46 log(10) cfu/mL), respectively. However, in skimmed and 3.6% fat milk samples, complete inactivation was not achieved and, during the subsequent 15 d of storage at 4 degrees C, L. monocytogenes was able to recover and replicate until achieving initial counts. In milk samples with 10 and 15% fat, L. monocytogenes recovered to the level of initial counts only in the milk samples treated at 200 MPa but not in the milk samples treated at 300 and 400 MPa. When the load of L. monocytogenes was approximately 3.0 log(10) cfu/mL in milk samples with 0.3 and 3.6% fat, complete inactivation was not achieved and L. monocytogenes was able to recover and grow during the subsequent cold storage. Fat content increased the maximum temperature reached during UHPH treatment; this could have contributed to the lethal effect achieved, but the amount of fat of the milk had a stronger effect than the temperature on obtaining a higher death rate of L. monocytogenes.

  20. Antimicrobial treatments to control Listeria monocytogenes in queso fresco.

    Science.gov (United States)

    Lourenço, António; Kamnetz, Mary B; Gadotti, Camila; Diez-Gonzalez, Francisco

    2017-06-01

    Queso fresco, is a Hispanic non-fermented cheese highly susceptible to contamination with L. monocytogenes. This research was aimed to determine the effect of GRAS antimicrobial ingredients to control L. monocytogenes. Antimicrobials included caprylic acid (CA), Nisaplin(®) (N, 2.5% nisin), a mixture of sodium lactate and sodium diacetate (SL/SD), Lactococcus lactis sbp. lactis DPC 3147, monolaurin, and lactic acid (LA). Batches of queso fresco curds were inoculated with 10(4) CFU/g and stored at 4 °C for three weeks. During storage the count of L. monocytogenes reached 7 to 8 Log CFU/g in control samples. Most individual antimicrobial treatments resulted in less than 1 Log CFU/g reductions in final counts, with the exception of N (0.5 g/kg) and CA (2.9 g/kg) that caused more than 3 and 5 Log CFU/g differences with controls, respectively. Mixtures of ingredients were more effective in inhibiting L. monocytogenes growth, and treatments with N and CA consistently delivered 6 Log CFU/g less counts than controls. Supplementation of 12 g/kg LA to treatments with SL/SD (3%/0.22%) caused differences of more than 4 Log CFU/g in final Listeria populations. Samples treated with the binary mixtures of N and CA (0.5 and 0.7 g/kg, respectively) were evaluated in a consumer panel (n = 67). Panelists slightly preferred control and commercial over treated samples, but all samples were in average rated between "slightly liking" and "moderately liking." These experiments indicated that combined use of antimicrobial ingredients may be an effective way to control the population of Listeria monocytogenes in queso fresco.

  1. Diferenciação entre Listeria monocytogenes e Erysipelothrix rhusiopathiae com o clorêto de Trifeniltetrazólio

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    Vinicius Moreira Dias

    1958-12-01

    Full Text Available Experiências foram realizadas com bactérias dos gêneros Listeria e Erysipelothrix, em meios líquido e sólido, utilizando o clorêto de 2, 3, 5 - trifeniltetrazólio. A atividade enzimática redutora das listérias para o TTC foi diferente da do E. rhusiopathiae, principalmente em meio líquido e nas horas iniciais de observação. Preparações feitas para microscopia ótica e electrônica dos germes tratados com TTC revelaram a presença de granulações polares, bipolares e centrais dentro do corpo das listérias. A evidenciação de granulações coradas de formazana, intracelulares nas listérias, confirma estudos anteriores quanto à possibilidade da existência de mitocôndrias nas bactérias.Based on a similarity of cultural and biochemical properties, WILSON and MILLES (6 compared the microorganisms of listeriosis with those of swine erysipelas including them in the genus Erysipelothrix with the species E. monocytogenes and E. rhusiopathiae. However, BARBER (1 and JULIANELLE (4, in a comparative study of both microorganisms, do not admit that possibility. Observing the morphological and citochemical characteristics of L. monocytogenes (N.º 7 973, 5 348, 5 105, 5 214, of the Seeliger collection and E. ehusiopathiae cultures (N.º 1, 7, 11, 27, 37, of the WIX collection, both in phase "S", we were able to verify their comparative behavior when in contact with 2-3-5-triphenyltetrazolium chloride (TTC, "Synthetical Laboratories, Chicago, U.S.A". 1. To 1,0 ml of cultures of both microorganisms grown in plain broth plus 5% horse serum for 24 hours at 37ºC, 0.1 ml of sterilized 1% aqueous solution of TTC was added. The tubes were left at room temperature (± 25ºC or in the incubator (37ºC. In the tubes with L. monocytogenes immediately appeared a red coloration (fig. 1 characteristic of formazan production, that became gradually more pronounced, from bottom to top (figs. 2, 3, 4, 5; at the and of 24 hours the color was intense the tube

  2. Validation of the ANSR(®) Listeria monocytogenes Method for Detection of Listeria monocytogenes in Selected Food and Environmental Samples.

    Science.gov (United States)

    Caballero, Oscar; Alles, Susan; Le, Quynh-Nhi; Gray, R Lucas; Hosking, Edan; Pinkava, Lisa; Norton, Paul; Tolan, Jerry; Mozola, Mark; Rice, Jennifer; Chen, Yi; Ryser, Elliot; Odumeru, Joseph

    2016-01-01

    Work was conducted to validate performance of the ANSR(®) for Listeria monocytogenes method in selected food and environmental matrixes. This DNA-based assay involves amplification of nucleic acid via an isothermal reaction based on nicking enzyme amplification technology. Following single-step sample enrichment for 16-24 h for most matrixes, the assay is completed in 40 min using only simple instrumentation. When 50 distinct strains of L. monocytogenes were tested for inclusivity, 48 produced positive results, the exceptions being two strains confirmed by PCR to lack the assay target gene. Forty-seven nontarget strains (30 species), including multiple non-monocytogenes Listeria species as well as non-Listeria, Gram-positive bacteria, were tested, and all generated negative ANSR assay results. Performance of the ANSR method was compared with that of the U.S. Department of Agriculture, Food Safety and Inspection Service Microbiology Laboratory Guidebook reference culture procedure for detection of L. monocytogenes in hot dogs, pasteurized liquid egg, and sponge samples taken from an inoculated stainless steel surface. In addition, ANSR performance was measured against the U.S. Food and Drug Administration Bacteriological Analytical Manual reference method for detection of L. monocytogenes in Mexican-style cheese, cantaloupe, sprout irrigation water, and guacamole. With the single exception of pasteurized liquid egg at 16 h, ANSR method performance as quantified by the number of positives obtained was not statistically different from that of the reference methods. Robustness trials demonstrated that deliberate introduction of small deviations to the normal assay parameters did not affect ANSR method performance. Results of accelerated stability testing conducted using two manufactured lots of reagents predicts stability at the specified storage temperature of 4°C of more than 1 year.

  3. Automatic agar tray inoculation device

    Science.gov (United States)

    Wilkins, J. R.; Mills, S. M.

    1972-01-01

    Automatic agar tray inoculation device is simple in design and foolproof in operation. It employs either conventional inoculating loop or cotton swab for uniform inoculation of agar media, and it allows technician to carry on with other activities while tray is being inoculated.

  4. Antimicrobial Activity of Chitosan Films With Essential Oils Against Listeria monocytogenes on Cabbage

    Science.gov (United States)

    Jovanovic, Gordana D.; Klaus, Anita S.; P. Niksic, Miomir

    2016-01-01

    Background The highest incidence of listeriosis, due to consumption of ready-to-eat foods and fresh, shredded, minimally processed vegetables, occurs among pregnant women and the elderly. In order to reduce the prevalence of listeriosis among consumers, better protective measures are recommended. Chitosan films, with or without added essential oils, represent a modern, safe method of preserving the quality of such vegetables and significantly reducing the incidence of Listeria monocytogenes in these foods. Objectives The present study was conducted to evaluate the antimicrobial properties of composite chitosan-gelatin films with and without essential oils against two strains of L. monocytogenes, ATCC 19115 and ATCC 19112, in fresh shredded cabbage. Methods Shredded cabbage was inoculated with L. monocytogenes and packed between two layers of the chitosan composite film, then placed in Petri dishes. The prepared samples were stored at 4°C then analyzed for total viable count on PALCAM agar while incubated at 37°C, every 24 hours for 7 days. Results Average L. monocytogenes content ranged from 4.2 - 5.4 log CFU/g, reaching values of 7.2 - 8.6 log CFU/g in samples of untreated cabbage. A complete reduction of L. monocytogenes ATCC 19115 on cabbage was achieved after 120 hours in the presence of 0.5% chitosan film, whereas reduction of L. monocytogenes ATCC 19112 was achieved after 144 hours. In the presence of 1% chitosan film, the bacteria withered more quickly and complete reduction of both species of L. monocytogenes was achieved after 96 hours. Conclusions All tested formulations of chitosan films exhibited strong antimicrobial activity on the growth of both strains of L. monocytogenes on cabbage. The best effect was achieved with a 1% chitosan concentration. The addition of essential oils increased the antimicrobial activity of all tested films. PMID:27800143

  5. In Vitro Evaluation of Bacteriocins Activity Against Listeria monocytogenes Biofilm Formation.

    Science.gov (United States)

    Camargo, Anderson Carlos; de Paula, Otávio Almeida Lino; Todorov, Svetoslav Dimitrov; Nero, Luís Augusto

    2016-03-01

    The present study aimed to assess the activity of cell-free supernatant (CFS) containing bacteriocins on the formation and maintenance of biofilms developed by Listeria monocytogenes, and the associated effect of bacteriocins and ethylene-diamine-tetra-acetic acid (EDTA) on the formed biofilm. CFS from 9 lactic acid bacteria (LAB) strains was tested for inhibitory activity against 85 L. monocytogenes isolates and 21 LAB strains. Then, 12 L. monocytogenes strains were selected based on genetic profiles and sensitivity to CFS and were subjected to an in vitro assay to assess biofilm formation in microtiter plates, considering different culture media and incubation conditions. Based on these results, 6 L. monocytogenes strains were subjected to the same in vitro procedure to assess biofilm formation, being co-inoculated with CFS. In addition, these strains were subjected to the same in vitro procedure, modified by adding the CFS after biofilm formation. Relevant decrease in biofilm formation was observed in the first experiment, but CFS added after biofilm formation did not eliminate them. CFS from Lactobacillus curvatus ET31 were selected due to its anti-biofilm activity, being associated to EDTA at different concentrations and tested for biofilm control of three strains of L. monocytogenes, using the same in vitro procedure described previously. Concentrated bacteriocin presented poor performance in eliminating formed biofilms, and EDTA concentration presented no evident interference on biofilm elimination. Twelve selected L. monocytogenes strains were positive for investigated virulence makers and negative for luxS gene, recognized as being involved in biofilm formation. Selected L. monocytogenes strains were able to produce biofilms under different conditions. CFSs have the potential to prevent biofilm formation, but they were not able to destroy already formed biofilms. Nevertheless, low concentrations of CFS combined with EDTA caused a relevant reduction in

  6. Comparative Evaluation of Veriflow® Listeria monocytogenes to USDA and AOAC Culture Based Methods for the Detection of Listeria monocytogenes in Food.

    Science.gov (United States)

    Joelsson, Adam C; Brown, Ashley S; Puri, Amrita; Keough, Martin P; Gaudioso, Zara E; Siciliano, Nicholas A; Snook, Adam E

    2015-01-01

    Veriflow® Listeria monocytogenes (LM) is a molecular based assay for the presumptive detection of Listeria monocytogenes from environmental surfaces, dairy, and ready-to-eat (RTE) food matrixes (hot dogs and deli meat). The assay utilizes a PCR detection method coupled with a rapid, visual, flow-based assay that develops in 3 min post PCR amplification and requires only 24 h of enrichment for maximum sensitivity. The Veriflow LM system eliminates the need for sample purification, gel electrophoresis, or fluorophore-based detection of target amplification, and does not require complex data analysis. This Performance Tested Method(SM) validation study demonstrated the ability of the Veriflow LM method to detect low levels of artificially inoculated L. monocytogenes in seven distinct environmental and food matrixes. In each unpaired reference comparison study, probability of detection analysis indicated no significant difference between the Veriflow LM method and the U.S. Department of Agriculture, Food Safety and Inspection Service Microbiology Laboratory Guidebook 8.08 or AOAC 993.12 reference method. Fifty strains of L. monocytogenes were detected in the inclusivity study, while 39 nonspecific organisms were undetected in the exclusivity study. The study results show that Veriflow LM is a sensitive, selective, and robust assay for the presumptive detection of L. monocytogenes sampled from environmental, dairy, or RTE (hot dogs and deli meat) food matrixes.

  7. Antilisterial properties of marinades during refrigerated storage and microwave oven reheating against post-cooking inoculated chicken breast meat.

    Science.gov (United States)

    Fouladkhah, Aliyar; Geornaras, Ifigenia; Nychas, George-John; Sofos, John N

    2013-02-01

    This study evaluated growth of Listeria monocytogenes inoculated on cooked chicken meat with different marinades and survival of the pathogen as affected by microwave oven reheating. During aerobic storage at 7 °C, on days 0, 1, 2, 4, and 7, samples were reheated by microwave oven (1100 W) for 45 or 90 s and analyzed microbiologically. L. monocytogenes counts on nonmarinated (control) samples increased (P Microwave oven reheating reduced L. monocytogenes counts by 1.9 to 4.1 (45 s) and >2.4 to 5.0 (90 s) log CFU/g. With similar trends across different marinates, the high levels of L. monocytogenes survivors found after microwave reheating, especially after storage for more than 2 d, indicate that length of storage and reheating time need to be considered for safe consumption of leftover cooked chicken.

  8. [Hematometra & Listeria monocytogenes].

    Science.gov (United States)

    Gómez Arzapalo, E; Pérez Mendizábal, A; Herrera Avalos, I; Gorozpe Calvillo, J I

    2001-05-01

    The hematometra is a nosological entity that may not always be attributed to an embryonic defect of the paramesonefros; cervical-vaginal infections such as etiological possibilities due to Listeria monocytogenes (Lm), cervix malignant neoplasias, iatrogenias due to endometrial ablation with Lasser, traumatic bloody uterine curetage and because of cervical cryocoagulation or electrocoagulation are also mentioned. The case to be reported is from a woman in reproductive stage, who is 32 years old, and had menarca at the age of 13, starting her sexual life at 31, not using any method to control her fertility. When having an eight-week amenorrhea after 8 months of marriage, she visited the doctor for assumed pregnancy, within the prenatal analysis a pelvic echographic study was requested, finding out images that we concluded as hematometra, having been drained and demonstrated the presence of LM by anti-Lm antibodies, being administered Azitromicina and Espiramicina.

  9. Inactivation of Listeria monocytogenes, Salmonella spp. and Escherichia coli O157:H7 on cantaloupes by octenidine hydrochloride

    Science.gov (United States)

    This study investigated the efficacy of a new generation disinfectant, namely octenidine dihydrochloride (OH) as wash and coating treatments for reducing Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7 on cantaloupe surface. Cantaloupe rind plugs inoculated separately with L. m...

  10. Inactivation of Listeria monocytogenes in Skim Milk and Liquid Egg White by Antimicrobial Bottle Coating with Polylactic Acid and Nisin

    Science.gov (United States)

    This study was to develop an antimicrobial bottle coating method to reduce the risk of outbreaks of human listeriosis caused by contaminated liquid foods. Liquid egg white and skim milk were inoculated with Listeria monocytogenes Scott A and stored in glass jars that were coated with a mixture of po...

  11. BEHAVIOR OF ESCHERICHIA COLI O157:H7, LISTERIA MONOCYTOGENES, AND SALMONELLA TYPHIMURIUM IN TEEWURST, A RAW SPREADABLE SAUSAGE

    Science.gov (United States)

    The fate of Listeria monocytogenes, Salmonella Typhimurium, or Escherichia coli O157:H7 were separately monitored both in and on teewurst, a traditional raw and spreadable sausage of Germanic origin. Multi-strain cocktails of each pathogen (ca. 5.0 log CFU/g) were used to separately inoculate teewur...

  12. Changes in Gene Expression during Adaptation of Listeria monocytogenes to the Soil Environment

    Science.gov (United States)

    Piveteau, Pascal; Depret, Géraldine; Pivato, Barbara; Garmyn, Dominique; Hartmann, Alain

    2011-01-01

    Listeria monocytogenes is a ubiquitous opportunistic pathogen responsible for listeriosis. In order to study the processes underlying its ability to adapt to the soil environment, whole-genome arrays were used to analyse transcriptome modifications 15 minutes, 30 minutes and 18 h after inoculation of L. monocytogenes EGD-e in soil extracts. Growth was observed within the first day of incubation and large numbers were still detected in soil extract and soil microcosms one year after the start of the experiment. Major transcriptional reprofiling was observed. Nutrient acquisition mechanisms (phosphoenolpyruvate-dependent phosphotransferase systems and ABC transporters) and enzymes involved in catabolism of specific carbohydrates (β-glucosidases; chitinases) were prevalent. This is consistent with the overrepresentation of the CodY regulon that suggests that in a nutrient depleted environment, L. monocytogenes recruits its extensive repertoire of transporters to acquire a range of substrates for energy production. PMID:21966375

  13. Antibacterial activity of bacteriocin-like substance P34 on Listeria monocytogenes in chicken sausage

    Science.gov (United States)

    Sant’Anna, Voltaire; Quadros, Deoni A.F.; Motta, Amanda S.; Brandelli, Adriano

    2013-01-01

    The antimicrobial activity of the bacteriocin-like substance (BLS) P34 against Listeria monocytogenes was investigated in chicken sausage. The BLS was applied to chicken sausages (256 AU g−1) previously inoculated with a suspension of 102 cfu g−1 of L. monocytogenes. BLS P34 inhibited the indicator microorganism in situ in all incubation times for up to 10 days at 5 °C. The effectiveness of BLS P34 was increased when it was added in combination with nisin. The bacteriocin was also tested in natural eatable natural bovine wrapping (salty semi-dried tripe) against the same indicator microorganism, also showing inhibitory capability in vitro. BLS P34 showed potential to control L. monocytogenes in refrigerated meat products. PMID:24688506

  14. Antibacterial activity of bacteriocin-like substance P34 on Listeria monocytogenes in chicken sausage

    Directory of Open Access Journals (Sweden)

    Voltaire Sant'Anna

    2013-12-01

    Full Text Available The antimicrobial activity of the bacteriocin-like substance (BLS P34 against Listeria monocytogenes was investigated in chicken sausage. The BLS was applied to chicken sausages (256 AU g-1 previously inoculated with a suspension of 10² cfu g-1 of L. monocytogenes. BLS P34 inhibited the indicator microorganism in situ in all incubation times for up to 10 days at 5 °C. The effectiveness of BLS P34 was increased when it was added in combination with nisin. The bacteriocin was also tested in natural eatable natural bovine wrapping (salty semi-dried tripe against the same indicator microorganism, also showing inhibitory capability in vitro. BLS P34 showed potential to control L. monocytogenes in refrigerated meat products.

  15. Antibacterial activity of bacteriocin-like substance P34 on Listeria monocytogenes in chicken sausage.

    Science.gov (United States)

    Sant'Anna, Voltaire; Quadros, Deoni A F; Motta, Amanda S; Brandelli, Adriano

    2013-12-01

    The antimicrobial activity of the bacteriocin-like substance (BLS) P34 against Listeria monocytogenes was investigated in chicken sausage. The BLS was applied to chicken sausages (256 AU g(-1)) previously inoculated with a suspension of 10(2) cfu g(-1) of L. monocytogenes. BLS P34 inhibited the indicator microorganism in situ in all incubation times for up to 10 days at 5 °C. The effectiveness of BLS P34 was increased when it was added in combination with nisin. The bacteriocin was also tested in natural eatable natural bovine wrapping (salty semi-dried tripe) against the same indicator microorganism, also showing inhibitory capability in vitro. BLS P34 showed potential to control L. monocytogenes in refrigerated meat products.

  16. Inhibition of Listeria monocytogenes and Salmonella by combinations of oriental mustard, malic acid, and EDTA.

    Science.gov (United States)

    Olaimat, Amin N; Holley, Richard A

    2014-04-01

    The antimicrobial activities of oriental mustard extract alone or combined with malic acid and EDTA were investigated against Salmonella spp. or Listeria monocytogenes at different temperatures. Five strain Salmonella or L. monocytogenes cocktails were separately inoculated in Brain Heart Infusion broth containing 0.5% (w/v) aqueous oriental mustard extract and incubated at 4 °C to 21 °C for 21 d. For inhibitor combination tests, Salmonella Typhimurium 02:8423 and L. monocytogenes 2-243 were individually inoculated in Mueller Hinton broth containing the mustard extract with either or both 0.2% (w/v) malic acid and 0.2% (w/v) EDTA and incubated at 10 °C or 21 °C for 10 to 14 d. Mustard extract inhibited growth of the L. monocytogenes cocktail at 4 °C up to 21 d (2.3 log10 CFU/mL inhibition) or at 10 °C for 7 d (2.4 log10 CFU/mL inhibition). Salmonella spp. viability was slightly, but significantly reduced by mustard extract at 4 °C by 21 d. Although hydrolysis of sinigrin in mustard extract by both pathogens was 2 to 6 times higher at 21 °C than at 4 °C to 10 °C, mustard was not inhibitory at 21 °C, perhaps because of the instability of its hydrolysis product (allyl isothiocyanate). At 21 °C, additive inhibitory effects of mustard extract with EDTA or malic acid led to undetectable levels of S. Typhimurium and L. monocytogenes by 7 d and 10 d, respectively. At 10 °C, S. Typhimurium was similarly susceptible, but combinations of antimicrobials were not more inhibitory to L. monocytogenes than the individual agents.

  17. Fødevarebetinget listeria monocytogenes endokarditis

    DEFF Research Database (Denmark)

    Frydland, Martin; Bundgaard, Henning; Moser, Claus

    2014-01-01

    Infection with Listeria monocytogenes is rare and mainly seen in immunosuppressed patients. Infection with L. monocytogenes has a mortality rate of 30%. We present a case report of L. monocytogenes bacteraemia and endocarditis in a 70-year-old man with several co-morbidities and following four...... major surgical procedures. This illustrates the findings and characteristics in one of the 16 patients who died in 2013 and 2014 this summer due to sausage-related L. monocytogenes infection....

  18. A Dual Microscopy-Based Assay To Assess Listeria monocytogenes Cellular Entry and Vacuolar Escape.

    Science.gov (United States)

    Quereda, Juan J; Pizarro-Cerdá, Javier; Balestrino, Damien; Bobard, Alexandre; Danckaert, Anne; Aulner, Nathalie; Shorte, Spencer; Enninga, Jost; Cossart, Pascale

    2015-10-23

    Listeria monocytogenes is a Gram-positive bacterium and a facultative intracellular pathogen that invades mammalian cells, disrupts its internalization vacuole, and proliferates in the host cell cytoplasm. Here, we describe a novel image-based microscopy assay that allows discrimination between cellular entry and vacuolar escape, enabling high-content screening to identify factors specifically involved in these two steps. We first generated L. monocytogenes and Listeria innocua strains expressing a β-lactamase covalently attached to the bacterial cell wall. These strains were then incubated with HeLa cells containing the Förster resonance energy transfer (FRET) probe CCF4 in their cytoplasm. The CCF4 probe was cleaved by the bacterial surface β-lactamase only in cells inoculated with L. monocytogenes but not those inoculated with L. innocua, thereby demonstrating bacterial access to the host cytoplasm. Subsequently, we performed differential immunofluorescence staining to distinguish extracellular versus total bacterial populations in samples that were also analyzed by the FRET-based assay. With this two-step analysis, bacterial entry can be distinguished from vacuolar rupture in a single experiment. Our novel approach represents a powerful tool for identifying factors that determine the intracellular niche of L. monocytogenes.

  19. The influence of mayonnaise pH and storage temperature on the growth of Listeria monocytogenes in seafood salad.

    Science.gov (United States)

    Hwang, Cheng-An; Tamplin, Mark L

    2005-07-25

    Seafood salad has been identified as a ready-to-eat food with a relatively high incidence of contamination by Listeria monocytogenes; however, little is known about the behavior of this pathogen in seafood salad as a function of product pH and storage temperature. To produce data towards the development of a predictive growth model, a 6-strain cocktail of L. monocytogenes was inoculated onto the surface of a shrimp-crabmeat product, mixed with mayonnaise that was previously adjusted with NaOH to pH 3.7, 4.0, 4.4, 4.7 or 5.1, and then stored at 4 degrees , 8 degrees or 12 degrees C under both aerobic and vacuum conditions. At each storage temperature, L. monocytogenes was able to grow in the seafood salad under both aerobic and vacuum conditions. The slowest growth of L. monocytogenes was observed in seafood salad with a mayonnaise pH of 3.7 and a storage temperature of 4 degrees C under vacuum condition. In salad with the same mayonnaise pH, the growth rate (GR, log10 cfu/h) of L. monocytogenes increased as a function of storage temperature. At the same storage temperature, the lag phase duration (LPD, h) of L. monocytogenes decreased as mayonnaise pH increased. At the same mayonnaise pH and temperature, LPD of L. monocytogenes was greater under aerobic than under vacuum conditions. Regression analyses indicated that mayonnaise pH is the main effector on the LPD of L. monocytogenes in seafood salad, and storage temperature was the main effector on the GR. Secondary models that describe LPD and GR of L. monocytogenes in seafood salad as a function of mayonnaise pH and storage temperature were produced.

  20. Reducing levels of Listeria monocytogenes contamination on raw salmon with acidified sodium chlorite.

    Science.gov (United States)

    Su, Yi-Cheng; Morrissey, Michael T

    2003-05-01

    The antimicrobial activity of acidified sodium chlorite (ASC) against Listeria monocytogenes in salmon was studied. Raw salmon (whole fish and fillets) inoculated with L. monocytogenes (10(3) CFU/cm2 or 10(4) CFU/g) were washed with ASC solution (50 ppm) for 1 min and stored at -18 degrees C for 1 month (whole salmon) or in ice for 7 days (fillets). L. monocytogenes populations were determined for whole salmon after frozen storage and for fillets on days 1, 3, 5, and 7 of storage. A wash with ASC solution followed by ASC glazing did not reduce L. monocytogenes on the skin of whole salmon during frozen storage. However, the wash resulted in an L. monocytogenes reduction of 0.5 log CFU/g for salmon fillets. The populations of L. monocytogenes in fillets increased slowly during ice storage, but the growth of these populations was retarded by ASC ice. By day 7, the populations were 0.25 log units smaller in fillets stored in ASC ice and 0.62 log units smaller in fillets that had been washed with ASC solution and stored in ASC ice than in control fillets. Treatment with ASC also reduced total plate counts (TPCs) by 0.43 log CFU/cm2 on the skin of whole salmon and by 0.31 log CFU/g in fillets. The TPCs for skin decreased during frozen storage but increased gradually for fillets stored at 5 degrees C or in ice. However, TPCs of ASC-treated samples were lower than those for controls at any point during the study. Washing with ASC solution significantly (P < 0.05) reduced TPCs on the skin of whole salmon and in fillets, as well as L. monocytogenes in fillets. The antimicrobial activity of ASC was enhanced when salmon was washed with ASC solution and stored in ASC ice.

  1. Rapid detection of Listeria monocytogenes by real-time PCR in processed meat and dairy products.

    Science.gov (United States)

    Heo, Eun Jeong; Song, Bo Ra; Park, Hyun Jung; Kim, Young Jo; Moon, Jin San; Wee, Sung Hwan; Kim, Jin-Seok; Yoon, Yohan

    2014-03-01

    The objectives of this study were to evaluate the detection of Listeria monocytogenes in different ready-to-eat foods using real-time PCR (RT-PCR). Various concentrations (10(0) to 10(5) CFU/ml) of L. monocytogenes ATCC 19115 were inoculated into ham, sausage, ground meat, processed milk, cheese, and infant formula. L. monocytogenes ATCC 19115 in the samples was then enumerated on Oxford agar, and DNA was extracted from the samples before and after incubation at 36°C for 4 h. A set of primers and hybridization probe designed in this study was then used to detect the pathogen. The standard curve was then prepared by plotting cycle threshold values for each dilution versus L. monocytogenes cell counts (log CFU). The specificity of the set of primers and hybridization probe was appropriate. A 4-h incubation at 36°C before DNA extraction produced optimum standard curves in comparison to the results for a 0-h incubation. Thus, a 4-h incubation at 36°C was applied for monitoring L. monocytogenes in collected food samples. To monitor L. monocytogenes in foods, 533 samples (ham, 129; sausage, 226; ground meat, 72; processed cheese, 54; processed milk, 42; and infant formula, 10) were collected from retail markets and from the step before pasteurization in plants. Of all 533 samples, 4 samples (0.8%) showed positive signals in RT-PCR. Two samples from hams (1.6%) and two samples from sausages (0.9%) were determined to be positive for L. monocytogenes at processed meat and milk products.

  2. Assessment of Listeria monocytogenes virulence in the Galleria mellonella insect larvae model

    Science.gov (United States)

    Rakic Martinez, Mira; Ferguson, Martine; Datta, Atin R.

    2017-01-01

    Several animal models have been used to understand the molecular basis of the pathogenicity, infectious dose and strain to strain variation of Listeria monocytogenes. The greater wax worm Galleria mellonella, as an alternative model, provides some useful advantages not available with other models and has already been described as suitable for the virulence assessment of various pathogens including L. monocytogenes. The objectives of this study are: 1) confirming the usefulness of this model with a wide panel of Listeria spp. including non-pathogenic L. innocua, L. seeligeri, L. welshimeri and animal pathogen L. ivanovii; 2) assessment of virulence of several isogenic in-frame deletion mutants in virulence and stress related genes of L. monocytogenes and 3) virulence assessment of paired food and clinical isolates of L. monocytogenes from 14 major listeriosis outbreaks occurred worldwide between 1980 and 2015. Larvae injected with different concentrations of Listeria were incubated at 37°C and monitored over seven days for time needed to kill 50% of larvae (LT50) and to determine change of bacterial population in G. mellonella, 2 and 24 hours post-inoculation. Non-pathogenic members of Listeria and L. ivanovii showed significantly (P monocytogenes strains. Isogenic mutants of L. monocytogenes with the deletions in prfA, plcA, hly, actA and virR genes, also showed significantly (P monocytogenes strains related to non-invasive (gastroenteritis) outbreaks of listeriosis showed significantly (P < 0.05) lower virulence than isolates of the same serotype obtained from outbreaks with invasive symptoms. The difference, however, was dose and strain- dependent. No significant differences in virulence were observed among the serotype tested in this study. PMID:28898264

  3. Effect of gamma-irradiation on the survival of Listeria monocytogenes and allergenicity of cherry tomatoes

    Science.gov (United States)

    Todoriki, Setsuko; Bari, Latiful; Kitta, Kazumi; Ohba, Mika; Ito, Yasuhiro; Tsujimoto, Yuka; Kanamori, Norihito; Yano, Erika; Moriyama, Tatsuya; Kawamura, Yukio; Kawamoto, Shinichi

    2009-07-01

    The presence of Listeria monocytogenes in fresh produce is a growing concern because of the possibility of food-borne illness. Ionizing radiation is an effective non-thermal means of eliminating pathogenic bacteria in fresh produce; however, the effect of ionizing irradiation on the allergenic properties of the host commodities remains unknown. This study aimed (i) to determine the effective dose of gamma-irradiation in eliminating L. monocytogenes on whole cherry tomatoes and (ii) to evaluate the effect of gamma-irradiation on the allergenic properties of tomato proteins. Cherry tomatoes that were inoculated with a mixture of five L. monocytogenes strains were treated with gamma-rays from a 60Co source. A 1.25 kGy dose of gamma-irradiation was found to be sufficient to eliminate L. monocytogenes on whole cherry tomatoes. The immunoblot profile of serum samples obtained from two patients with tomato allergy revealed that gamma-irradiation did not affect the allergenicity of tomato proteins for up to 7 days after irradiation when the tomatoes were stored at 20 °C. Additionally, the m-RNA levels of β-fructofuranosidase, polygalacturonase, pectin esterase, and superoxide dismutase, the main allergenic proteins in tomato, were not affected by the applied irradiation dose. Thus, this study demonstrated that a 1.25 kGy dose of gamma-irradiation effectively eliminates L. monocytogenes on cherry tomatoes without affecting the expression of allergenic proteins in the fruits.

  4. Efficacy of Acetic Acid against Listeria monocytogenes Attached to Poultry Skin during Refrigerated Storage.

    Science.gov (United States)

    Gonzalez-Fandos, Elena; Herrera, Barbara

    2014-09-11

    This work evaluates the effect of acetic acid dipping on the growth of L. monocytogenes on poultry legs stored at 4 °C for eight days. Fresh inoculated chicken legs were dipped into either a 1% or 2% acetic acid solution (v/v) or distilled water (control). Changes in mesophiles, psychrotrophs, Enterobacteriaceae counts and sensorial characteristics (odor, color, texture and overall appearance) were also evaluated. The shelf life of the samples washed with acetic acid was extended by at least two days over the control samples washed with distilled water. L. monocytogenes counts before decontamination were 5.57 log UFC/g, and after treatment with 2% acetic acid (Day 0), L. monocytogenes counts were 4.47 log UFC/g. Legs washed with 2% acetic acid showed a significant (p acetic acid. This study demonstrates that while acetic acid did reduce populations of L. monocytogenes on meat, it did not completely inactivate the pathogen. The application of acetic acid may be used as an additional hurdle contributing to extend the shelf life of raw poultry and reducing populations of L. monocytogenes.

  5. Effect of gamma-irradiation on the survival of Listeria monocytogenes and allergenicity of cherry tomatoes

    Energy Technology Data Exchange (ETDEWEB)

    Todoriki, Setsuko [National Food Research Institute, Tsukuba, Ibaraki 305-8642 (Japan)], E-mail: setsuko@affrc.go.jp; Bari, Latiful; Kitta, Kazumi; Ohba, Mika; Ito, Yasuhiro; Tsujimoto, Yuka [National Food Research Institute, Tsukuba, Ibaraki 305-8642 (Japan); Kanamori, Norihito [Japan International Research Center for Agricultural Science, Tsukuba, Ibaraki 305-8686 (Japan); Yano, Erika; Moriyama, Tatsuya; Kawamura, Yukio [School of Agriculture, Kinki University, Nara-city, Nara 631-8505 (Japan); Kawamoto, Shinichi [National Food Research Institute, Tsukuba, Ibaraki 305-8642 (Japan)

    2009-07-15

    The presence of Listeria monocytogenes in fresh produce is a growing concern because of the possibility of food-borne illness. Ionizing radiation is an effective non-thermal means of eliminating pathogenic bacteria in fresh produce; however, the effect of ionizing irradiation on the allergenic properties of the host commodities remains unknown. This study aimed (i) to determine the effective dose of gamma-irradiation in eliminating L. monocytogenes on whole cherry tomatoes and (ii) to evaluate the effect of gamma-irradiation on the allergenic properties of tomato proteins. Cherry tomatoes that were inoculated with a mixture of five L. monocytogenes strains were treated with gamma-rays from a {sup 60}Co source. A 1.25 kGy dose of gamma-irradiation was found to be sufficient to eliminate L. monocytogenes on whole cherry tomatoes. The immunoblot profile of serum samples obtained from two patients with tomato allergy revealed that gamma-irradiation did not affect the allergenicity of tomato proteins for up to 7 days after irradiation when the tomatoes were stored at 20 deg. C. Additionally, the m-RNA levels of {beta}-fructofuranosidase, polygalacturonase, pectin esterase, and superoxide dismutase, the main allergenic proteins in tomato, were not affected by the applied irradiation dose. Thus, this study demonstrated that a 1.25 kGy dose of gamma-irradiation effectively eliminates L. monocytogenes on cherry tomatoes without affecting the expression of allergenic proteins in the fruits.

  6. Use of germicidal UV light to reduce low numbers of Listeria monocytogenes on raw chicken meat.

    Science.gov (United States)

    Berrang, M E; Meinersmann, R J; Frank, J F

    2013-11-01

    Listeria monocytogenes is a common constituent of the microbiological community in poultry processing plants and can be found in low numbers on raw poultry. Raw meat is the most important source of this pathogen in commercial cooking facilities. Germicidal UV light was tested as a means to kill L. monocytogenes inoculated onto broiler breast fillets. Treatments at 800 μW/ cm(2) for 5 s to 5 min of exposure were tested against inocula of 35 to 60 cells per fillet. All fillets were sampled by rinsing in enrichment broth, and surviving pathogens were quantified using most-probable-number (MPN) analysis. Five replications each with 5 fillets per treatment were analyzed to achieve 25 sample fillets per treatment. All treatment times resulted in a significant decrease in L. monocytogenes numbers compared with paired untreated controls. Treated samples retained 0.2 to 1.5 MPN L. monocytogenes per fillet, and exposure time had no significant effect on the number of surviving cells. A 5-s treatment with germicidal UV light has potential as an intervention method to limit the transfer of L. monocytogenes on raw skinless breast fillets from a slaughter plant to a cooking plant.

  7. Antimicrobial activity of chitosan coatings and films against Listeria monocytogenes on black radish.

    Science.gov (United States)

    Jovanović, Gordana D; Klaus, Anita S; Nikšić, Miomir P

    2016-01-01

    The antibacterial activity of chitosan coatings prepared with acetic or lactic acid, as well as of composite chitosan-gelatin films prepared with essential oils, was evaluated in fresh shredded black radish samples inoculated with Listeria monocytogenes ATCC 19115 and L. monocytogenes ATCC 19112 during seven days of storage at 4°C. The chitosan coating prepared with acetic acid showed the most effective antibacterial activity. All tested formulations of chitosan films exhibited strong antimicrobial activity on the growth of L. monocytogenes on black radish, although a higher inhibition of pathogens was achieved at higher concentrations of chitosan. The antimicrobial effect of chitosan films was even more pronounced with the addition of essential oils. Chitosan-gelatin films with thyme essential oils showed the most effective antimicrobial activity. A reduction of 2.4log10CFU/g for L. monocytogenes ATCC 19115 and 2.1log10CFU/g for L. monocytogenes ATCC 19112 was achieved in the presence of 1% chitosan film containing 0.2% of thyme essential oil after 24h of storage. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  8. [Design of SCM inoculation device].

    Science.gov (United States)

    Qian, Mingli; Xie, Haiyuan

    2014-01-01

    The first step of bacilli culture is inoculation bacteria on culture medium. Designing a device to increase efficiency of inoculation is significative. The new device is controlled by SCM. The stepper motor can drive the culture medium rotating, accelerating, decelerating, overturn and suspending. The device is high practicability and efficient, let inoculation easy for operator.

  9. Evaluation of the transfer of Listeria monocytogenes from stainless steel and high-density polyethylene to Bologna and American cheese.

    Science.gov (United States)

    Rodríguez, Andrés; McLandsborough, Lynne A

    2007-03-01

    The objective of this study was to determine the factors involved in the transfer of Listeria monocytogenes from surfaces to foods. We evaluated the influence of surface type (stainless steel and high-density polyethylene), inoculation method (biofilm growth and attached cells), hydration level (visibly dry and wet), and food type (bologna and American cheese). Each experiment included all 16 combinations and was repeated 11 times. A four-strain cocktail of L. monocytogenes was used to inoculate stainless steel and high-density polyethylene either as growing biofilms or attached cells. Slides were placed on a universal testing machine and brought into contact with food at a constant pressure (45 kPa) and time (30 s). Food slices were blended, the number of transferred cells was determined by plating, and the efficiency of transfer (EOT) was calculated. The results strongly suggest that stainless steel surfaces transferred more L. monocytogenes to foods than did polyethylene (P = 0.05). Independent of the surface, biofilms tended to transfer more L. monocytogenes to foods (EOT = 0.57) than did attached cells (EOT = 0.16). Among foods, L. monocytogenes was transferred to bologna more easily than to cheese (P 0.05). We hypothesize that drying weakens cell-to-cell interactions in biofilms and cell-to-surface interactions of biofilms and thus allows increased transfer of cells to food products.

  10. Effect of selected generally recognized as safe preservative sprays on growth of Listeria monocytogenes on chicken luncheon meat.

    Science.gov (United States)

    Islam, Mahbub; Chen, Jinru; Doyle, Michael P; Chinnan, Manjeet

    2002-05-01

    The ability of selected generally recognized as safe (GRAS) chemical preservatives to reduce populations or inhibit growth of Listeria monocytogenes on chicken luncheon meat was evaluated. Slices of luncheon meat were treated by evenly spraying onto their surfaces 0.2 ml of a solution of one of four preservatives (sodium benzoate, sodium propionate, potassium sorbate, and sodium diacetate) at one of three different concentrations (15, 20, or 25% [wt/vol]). Each slice was then surface inoculated with a five-strain mixture of 10(5) CFU of L. monocytogenes per ml, held at 4, 13, or 22 degrees C, and assayed for L. monocytogenes immediately after inoculation and at 3, 7, 10, and 14 days of storage. Initial reductions of L. monocytogenes populations ranged from 0.78 to 1.32 log10 CFU g(-1) at day 0 for sodium benzoate- or sodium diacetate-treated meat, whereas reductions for the sodium propionate or potassium sorbate treatments were only 0.14 to 0.36 log10 CFU g(-1). After 14 days of storage at 4 degrees C, L. monocytogenes populations on all treated slices were 1.5 to 3 log10 CFU g(-1) less than on the untreated slices. At 13 degrees C and after 14 days of storage, L. monocytogenes populations were 3.5 and 5.2 log10 CFU g(-1) less on luncheon meat slices treated with 25% sodium benzoate or 25% sodium diacetate, respectively, and ca. 2 log10 CFU g(-1) less when treated with 25% sodium propionate or 25% potassium sorbate than on untreated control slices. Only sodium diacetate was highly inhibitory to L. monocytogenes on meat slices held at 22 degrees C for 7 days or longer. Untreated luncheon meat held at 22 degrees C was visibly spoiled within 10 days, whereas there was no evidence of visible spoilage on any treated luncheon meat at 14 days of storage.

  11. Control of Listeria monocytogenes in fresh cheese using protective lactic acid bacteria.

    Science.gov (United States)

    Coelho, M C; Silva, C C G; Ribeiro, S C; Dapkevicius, M L N E; Rosa, H J D

    2014-11-17

    In the past years, there has been a particular focus on the application of bacteriocins produced by lactic acid bacteria (LAB) in controlling the growth of pathogenic bacteria in foods. The aim of this study was to select LAB strains with antimicrobial activity, previously isolated from a traditional Azorean artisanal cheese (Pico cheese), in order to identify those with the greatest potential in reducing Listeria monocytogenes in fresh cheese. Eight bacteriocin producer strains identified as Lactococcus lactis (1) and Enterococcus faecalis (7) were tested. In general, the bacteriocin-producing strains presented a moderate growth in fresh cheese at refrigeration temperatures (4 °C), increasing one log count in three days. They exhibited slow acidification capacity, despite the increased production of lactic acid displayed by some strains after 24h. Bacteriocin activity was only detected in the whey of fresh cheese inoculated with two Enterococcus strains, but all cheeses made with bacteriocin-producing strains inhibited L. monocytogenes growth in the agar diffusion bioassay. No significant differences were found in overall sensory evaluation made by a non-trained panel of 50-52 tasters using the isolates as adjunct culture in fresh cheese, with the exception of one Enterococcus strain. To test the effect of in situ bacteriocin production against L. monocytogenes, fresh cheese was made from pasteurized cows' milk inoculated with bacteriocin-producing LAB and artificially contaminated with approximately 10(6) CFU/mL of L. monocytogenes. The numbers of L. monocytogenes were monitored during storage of fresh cheese at refrigeration temperature (4 °C) for up to 15 days. All strains controlled the growth of L. monocytogenes, although some Enterococcus were more effective in reducing the pathogen counts. After 7 days, this reduction was of approximately 4 log units compared to the positive control. In comparison, an increase of 4 log CFU/mL in pathogen numbers was

  12. BIOTECON diagnostics foodproof Listeria monocytogenes Detection Kit, 5' nuclease in combination with the foodproof ShortPrep II Kit.

    Science.gov (United States)

    Junge, Benjamin; Grönewald, Cordt; Berghof-Jäger, Kornelia

    2012-01-01

    A method was developed for the detection of Listeria monocytogenes in food. The method is based on real-time PCR using hydrolysis probes (5' Nuclease). This advanced PCR method was designed to reduce the time necessary to achieve results from PCR reactions and to enable the user to monitor the amplification of the PCR product simultaneously, in real-time. After DNA isolation using the BIOTECON foodproof ShortPrep II Kit designed for the rapid preparation of L. monocytogenes DNA for direct use in PCR, the real-time detection of L. monocytogenes DNA is carried out using the foodproof Listeria monocytogenes Detection Kit. The kit provides primers and hydrolysis probes for sequence-specific detection, convenient premixed reagents, and controls for reliable interpretation of results. For the internal comparison study, three different foods (soft cheese, coalfish, and smoked ham) were analyzed, chosen from the 15 food groups recommended by the AOAC Research Institute for detection of L. monocytogenes. From each food, 20 samples were inoculated with a low level (1-10 CFU/25 g) and 20 samples with a high level (10-50 CFU/25 g) of L. monocytogenes. Additionally, five nonspiked samples were prepared from each food. Depending on the matrix, the food samples were examined with the test kits and compared with the cultural methods according to the U.S. Food and Drug Administration's Bacteriological Analytical Manual or the U.S. Department of Agriculture/Food Safety and Inspection Service Microbiology Laboratory Guidebook.

  13. Control of Listeria monocytogenes on cold-smoked salmon using chitosan-based antimicrobial coatings and films.

    Science.gov (United States)

    Jiang, Zheng; Neetoo, Hudaa; Chen, Haiqiang

    2011-01-01

    The relatively high incidence of Listeria monocytogenes in ready-to-eat (RTE) products such as cold-smoked salmon is of serious concern. The objective of this study was to evaluate the efficacy of chitosan-based edible coatings and films incorporating 3 generally recognized as safe (GRAS) antimicrobials, sodium lactate (SL), sodium diacetate (SD), and potassium sorbate (PS), against L. monocytogenes on cold-smoked salmon. Salmon samples were surface-inoculated with a 5-strain cocktail of Listeria monocytogenes to a final concentration of 4.4 log CFU/cm(2) and then either coated with chitosan solutions or wrapped with chitosan films with or without the 3 antimicrobials. The samples were then vacuum packaged and stored at 4 °C for 30 d. The chitosan coatings with or without the antimicrobials consistently showed higher efficacy against L. monocytogenes than chitosan films having the same compositions. The most effective film treatments, chitosan films containing 1.2% SL/0.25% SD or 2.4% SL, achieved ≥ 1.3 log reductions of L. monocytogenes during the 30 d of refrigerated storage, while the most effective coating treatments, chitosan coatings containing 1.2% SL/0.25% SD or 0.15% PS/0.125% SD, achieved ≥ 2.8 log reductions. Practical Application: This study shows that chitosan-based edible coatings and films hold promise and can potentially assist fishery industries in their efforts to control L. monocytogenes.

  14. .NET 4.5 parallel extensions

    CERN Document Server

    Freeman, Bryan

    2013-01-01

    This book contains practical recipes on everything you will need to create task-based parallel programs using C#, .NET 4.5, and Visual Studio. The book is packed with illustrated code examples to create scalable programs.This book is intended to help experienced C# developers write applications that leverage the power of modern multicore processors. It provides the necessary knowledge for an experienced C# developer to work with .NET parallelism APIs. Previous experience of writing multithreaded applications is not necessary.

  15. Neuroinfections due to Listeria monocytogenes.

    Science.gov (United States)

    Streharova, A; Babjakova, A; Moravcikova, A; Harnicarova, A; Holeckova, K; Lesnakova, A; Sladeckova, V; Seckova, S; Kisac, P; Beno, P

    2007-11-01

    Listeria monocytogenes is not a rare pathogen causing meningitis, mainly in small children and in close contacts to livestock. The pathogen is naturally resistant to cephalosporins and some glycopeptides as well, therefore despite of syndromologic diagnosis of meningitis and initial therapy with 3rd generation cephalosporins according to the guidelines therapeutic failures with clinical consequences may occur.

  16. Microwave oven heating for inactivation of Listeria monocytogenes on frankfurters before consumption.

    Science.gov (United States)

    Rodríguez-Marval, Mawill; Geornaras, Ifigenia; Kendall, Patricia A; Scanga, John A; Belk, Keith E; Sofos, John N

    2009-10-01

    Microwave oven heating was evaluated for inactivation of Listeria monocytogenes on inoculated and stored frankfurters. Frankfurters formulated without/with 1.5% potassium lactate and 0.1% sodium diacetate were inoculated with L. monocytogenes (1.9 +/- 0.2 log CFU/cm(2)), vacuum-packaged, and stored (4 degrees C) to simulate conditions prior to purchase by consumers. At storage days 18, 36, and 54, packages were opened and placed at 7 degrees C, simulating aerobic storage in a household refrigerator. At 0, 3, and 7 d of aerobic storage, 2 frankfurters were placed in a bowl with water (250 mL) and treated in a household microwave oven at high (1100 W) power for 30, 45, 60, or 75 s, or medium (550 W) power for 60 or 75 s. Frankfurters and the heating water were analyzed for total microbial counts and L. monocytogenes populations. Exposure to high power for 75 s reduced pathogen levels (0.7 +/- 0.0 to 1.0 +/- 0.1 log CFU/cm(2)) to below the detection limit ( 1.5 and 5.9 log CFU/cm(2) from control levels of 1.5 +/- 0.1 to 7.2 +/- 0.5 log CFU/cm(2). Depending on treatment and storage time, the water used to reheat the frankfurters had viable L. monocytogenes counts of microwave oven at high power for 75 s to inactivate up to 3.7 log CFU/cm(2) of L. monocytogenes contamination.

  17. Control of Listeria monocytogenes growth in soft cheeses by bacteriophage P100

    Directory of Open Access Journals (Sweden)

    Elaine Nóbrega Gibson Silva

    2014-01-01

    Full Text Available The purpose of this study was to determine the effect of bacteriophage P100 on strains of Listeria monocytogenes in artificially inoculated soft cheeses. A mix of L. monocytogenes 1/2a and Scott A was inoculated in Minas Frescal and Coalho cheeses (approximately 10(5 cfu/g with the bacteriophage added thereafter (8.3 x 10(7 PFU/g. Samples were analyzed immediately, and then stored at 10 ºC for seven days. At time zero, 30 min post-infection, the bacteriophage P100 reduced L. monocytogenes counts by 2.3 log units in Minas Frescal cheese and by 2.1 log units in Coalho cheese, compared to controls without bacteriophage. However, in samples stored under refrigeration for seven days, the bacteriophage P100 was only weakly antilisterial, with the lowest decimal reduction (DR for the cheeses: 1.0 log unit for Minas Frescal and 0.8 log units for Coalho cheese. The treatment produced a statistically significant decrease in the counts of viable cells (p < 0.05 and in all assays performed, we observed an increase of approximately one log cycle in the number of viable cells of L. monocytogenes in the samples under refrigeration for seven days. Moreover, a smaller effect of phages was observed. These results, along with other published data, indicate that the effectiveness of the phage treatment depends on the initial concentration of L. monocytogenes, and that a high concentration of phages per unit area is required to ensure sustained inactivation of target pathogens on food surfaces.

  18. Real-time PCR detection of Listeria monocytogenes in infant formula and lettuce following macrophage-based isolation and enrichment.

    Science.gov (United States)

    Day, J B; Basavanna, U

    2015-01-01

    To develop a rapid detection procedure for Listeria monocytogenes in infant formula and lettuce using a macrophage-based enrichment protocol and real-time PCR. A macrophage cell culture system was employed for the isolation and enrichment of L. monocytogenes from infant formula and lettuce for subsequent identification using real-time PCR. Macrophage monolayers were exposed to infant formula and lettuce contaminated with a serial dilution series of L. monocytogenes. As few as approx. 10 CFU ml(-1) or g(-1) of L. monocytogenes were detected in infant formula and lettuce after 16 h postinfection by real-time PCR. Internal positive PCR controls were utilized to eliminate the possibility of false-negative results. Co-inoculation with Listeria innocua did not reduce the L. monocytogenes detection sensitivity. Intracellular L. monocytogenes could also be isolated on Listeria selective media from infected macrophage lysates for subsequent confirmation. The detection method is highly sensitive and specific for L. monocytogenes in infant formula and lettuce and establishes a rapid identification time of 20 and 48 h for presumptive and confirmatory identification, respectively. The method is a promising alternative to many currently used q-PCR detection methods which employ traditional selective media for enrichment of contaminated food samples. Macrophage enrichment of L. monocytogenes eliminates PCR inhibitory food elements and contaminating food microflora which produce cleaner samples that increase the rapidity and sensitivity of detection. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  19. Inactivation of Listeria monocytogenes on hams shortly after vacuum packaging by spray application of lauric arginate.

    Science.gov (United States)

    Taormina, P J; Dorsa, W J

    2009-12-01

    This study measured and compared the short-term efficacy levels of lauric arginate (LAE) as a postlethality treatment against Listeria monocytogenes present on varied surfaces of large-diameter hams. Preliminary in vitro work demonstrated a 5-log inactivation of L. monocytogenes in 5,000- and 9,090-ppm LAE solutions within 180 min at 4.4 and 23 degrees C. Six different whole-muscle ham types were inoculated with L. monocytogenes at ca. 7-log CFU per ham and spray treated with between 15 and 29 ml of a 9,090-ppm LAE solution, or an equal volume of water (control), prior to vacuum packaging. After 48 h at 4.4 degrees C, populations were recovered from ham and interior packaging surfaces by using a surface rinse method with Dey-Engley neutralizing broth followed by plating on modified Oxford medium. Logarithmic reductions of L. monocytogenes exceeding 2 log CFU/cm(2) of ham surfaces were achieved by LAE treatment on all ham types. Hams with 1,129 cm(2) of surface area that had been processed by drenching in liquid smoke had 3.84 and 2.67 CFU/cm(2) 48 h following treatment with 18 ml of water or LAE, respectively, but increasing treatment volumes to 22 ml significantly reduced (P < 0.05) L. monocytogenes levels to 0.65 log CFU/cm(2). This study demonstrated the efficacy of LAE against L. monocytogenes on several ham types, thereby validating it as a postlethality treatment for inactivation of the pathogen.

  20. Inhibition of Listeria monocytogenes by propionic acid-based ingredients in cured deli-style Turkey.

    Science.gov (United States)

    Glass, Kathleen A; McDonnell, Lindsey M; Von Tayson, Roxanne; Wanless, Brandon; Badvela, Mani

    2013-12-01

    Listeria monocytogenes growth can be controlled on ready-to-eat meats through the incorporation of antimicrobial ingredients into the formulation or by postlethality kill steps. However, alternate approaches are needed to provide options that reduce sodium content but maintain protection against pathogen growth in meats after slicing. The objective of this study was to determine the inhibition of L. monocytogenes by propionic acid-based ingredients in high-moisture, cured turkey stored at 4 or 7°C. Six formulations of sliced, cured (120 ppm of NaNO2 ), deli-style turkey were tested, including control without antimicrobials, 3.2% lactate-diacetate blend (LD), 0.4% of a liquid propionate-benzoate-containing ingredient, or 0.3, 0.4, and 0.5% of a liquid propionate-containing ingredient. Products were inoculated with 5 log CFU L. monocytogenes per 100-g package (3 log CFU/ml rinsate), vacuum-sealed, and stored at 4 or 7°C for up to 12 weeks; and populations were enumerated by plating on modified Oxford agar. As expected, the control without antimicrobials supported rapid growth, with >2 log average per ml rinsate increase within 4 weeks of storage at 4°C, whereas growth was observed at 6 weeks for the LD treatment. For both replicate trials, all treatments that contained liquid propionate or propionate-benzoate limited L. monocytogenes growth to an increase of 1-log increase) was observed in individual samples for all propionate-containing treatments at weeks 10, 11, and 12. As expected, L. monocytogenes grew more rapidly when products were stored at 7°C, but trends in relative inhibition were similar to those observed at 4°C. These results verify that propionate-based ingredients inhibit growth of L. monocytogenes on sliced, high-moisture, cured turkey and can be considered as an alternative to reduce sodium-based salts while maintaining food safety.

  1. Glycine betaine improves Listeria monocytogenes tolerance to desiccation on parsley leaves independent of the osmolyte transporters BetL, Gbu and OpuC.

    Science.gov (United States)

    Dreux, N; Albagnac, C; Sleator, R D; Hill, C; Carlin, F; Morris, C E; Nguyen-the, C

    2008-04-01

    To investigate the effect of glycine betaine (GB) on the survival of Listeria monocytogenes on leaf surfaces under low relative humidity (RH). The addition of GB (> or = 25 mmol l(-1)) improved the survival of L. monocytogenes under low RH on parsley leaves, thus suggesting that GB can improve the tolerance of L. monocytogenes to desiccation. Ten times less GB was needed to improve L. monocytogenes survival under low RH on nonbiological surfaces compared with parsley leaves, suggesting that, on the leaf surface, L. monocytogenes may have to compete for the available GB with autochthonous bacteria and/or the plant itself. Wild type and mutants carrying deletions in the three GB uptake systems, BetL, Gbu and OpuC, behaved similarly with and without added GB on parsley leaves (P > 0.05). In addition, preaccumulation of GB, triggered by osmotic stress prior to inoculation, failed to improve survival under low RH compared with osmotic stress without GB accumulation. Exogenous GB had a protective effect on L. monocytogenes cells from desiccation during survival on parsley leaves. This effect was independent of intracellular GB accumulation by the known uptake systems. Presence of GB could improve the survival of L. monocytogenes to desiccation on leaf surfaces and nonbiological surfaces.

  2. Biocontrole de Listeria monocytogenes por Pediococcus acidilactici em couve minimamente processada Biocontrol of Listeria monocytogenes by Pediococcus acidilactici in fresh-cut kale

    Directory of Open Access Journals (Sweden)

    Wanessa Altimiras Costa

    2009-12-01

    selected as a possible biological control bacterium. The population of L. monocytogenes inoculated in minimally processed kale increased 3.7 and 4.7 logarithmic cycles at 5 and 10 °C, respectively, after 20 days of storage and 4.6 logarithmic cycles at 15 °C after eight days. However, when 10(8 CFU.g-1 of P. acidilactici CCA3 was inoculated into processed product a reduction of L. monocytogenes of 2.3 logarithmic cycles under extreme temperature conditions (15 °C occurred. P. acidilactici CCA3 did not alter the titratable acidity or the kale sensorial characteristics during the shelf life period. These results suggest the potential application of biopreservatives on minimally processed kale that need to be associated with refrigeration and sanitation to assure safety.

  3. Effect of grapefruit seed extract on thermal inactivation of Listeria monocytogenes during sous-vide processing of two marinated Mexican meat entrées

    Science.gov (United States)

    D and z values of Listeria monocytogenes were obtained for two Mexican meat entrées: pork meat marinated in tomatillo (green tomato) sauce (PTS) and beef marinated in a red chili sauce (BRCS), with addition of 0, 200 and 800 ppm of grapefruit seed extract (GSE). Meat samples, inoculated with L.monoc...

  4. Use of a genetically enhanced, pediocin-producing starter culture, Lactococcus lactis subsp. lactis MM217, to control Listeria monocytogenes in cheddar cheese

    NARCIS (Netherlands)

    Buyong, N; Kok, J; Luchansky, JB

    1998-01-01

    Cheddar cheese was prepared with Lactococcus lactis subsp, lactis MM217, a starter culture which contains pMC117 coding for pediocin PA-1, About 75 liters of pasteurized milk (containing ca, 3.6% fat) was inoculated with strain MM217 (ca, 10(6) CFU per ml) and a mixture of three Listeria monocytogen

  5. Biological restoration: A 4/5 crown

    Directory of Open Access Journals (Sweden)

    Monize Ferreira Figueiredo de Carvalho

    2013-01-01

    Full Text Available Dental caries is one of the most prevalent conditions in humans; the purpose of restorative dentistry is to recreate the anatomy of the affected tooth thus the use of fragments from natural teeth as an effective restorative method. A maxillary first premolar left was prepared for an inverted 4/5 crown due to involvement of the vestibular face, after prepared received an allogeneic collage with similar color and dimension. Follow-up after 12 months indicated a stable restoration. Clinically, the site was without signs of caries, migration of the fragment or marginal infiltration. Biological restoration is a viable alternative for reestablishing function and esthetics to damaged/decayed teeth and therefore, biological restoration as an alternative to other restorative options.

  6. Effect of mayonnaise pH and storage temperature on the behavior of Listeria monocytogenes in ham salad and potato salad.

    Science.gov (United States)

    Hwang, Cheng-An

    2005-08-01

    This study examined and modeled the behavior of Listeria monocytogenes in ham salad and potato salad as affected by the pH of mayonnaise and storage temperature. An eight-strain cocktail of L. monocytogenes was inoculated on the surface of diced cooked ham or potato. The inoculated ham or potato was then mixed with regular mayonnaise (pH 3.8) or mayonnaise that was adjusted with NaOH to pH 4.2 or 4.6. The cell counts of L. monocytogenes in the salads during storage at 4, 8, or 12 degrees C were enumerated and used to model the behavior of L. monocytogenes in ham salad or potato salad. At each of the storage temperatures, L. monocytogenes was able to grow in ham salad, whereas L. monocytogenes was inactivated in potato salad. The growth rate (log CFU per hour) in ham salad or the inactivation rate (log CFU per hour) in potato salad increased as the storage temperature increased. The duration before growth in ham salad or inactivation in potato salad increased as storage temperature decreased. The mayonnaise pH showed no consistent effect on the growth rate or inactivation rate and duration before growth or inactivation occurred. Mathematical equations that described the growth rate or inactivation rate of L. monocytogenes in both salads as a function of mayonnaise pH and storage temperature were generated and shown to be satisfactory in describing the growth rate or inactivation rate of L. monocytogenes in the ham salad or potato salad.

  7. Modeling the Impact of Ingoing Sodium Nitrite, Sodium Ascorbate, and Residual Nitrite Concentrations on Growth Parameters of Listeria monocytogenes in Cooked, Cured Pork Sausage.

    Science.gov (United States)

    King, Amanda M; Glass, Kathleen A; Milkowski, Andrew L; Seman, Dennis L; Sindelar, Jeffrey J

    2016-02-01

    Sodium nitrite has been identified as a key antimicrobial ingredient to control pathogens in ready-to-eat (RTE) meat and poultry products, including Listeria monocytogenes. This study was designed to more clearly elucidate the relationship between chemical factors (ingoing nitrite, ascorbate, and residual nitrite) and L. monocytogenes growth in RTE meats. Treatments of cooked, cured pork sausage (65% moisture, 1.8% salt, pH 6.6, and water activity 0.98) were based on response surface methodology with ingoing nitrite and ascorbate concentrations as the two main factors. Concentrations of nitrite and ascorbate, including star points, ranged from 0 to 352 and 0 to 643 ppm, respectively. At one of two time points after manufacturing (days 0 and 28), half of each treatment was surface inoculated to target 3 log CFU/g of a five-strain L. monocytogenes cocktail, vacuum packaged, and stored at 7°C for up to 4 weeks. Growth of L. monocytogenes was measured twice per week, and enumerations were used to estimate lag time and growth rates for each treatment. Residual nitrite concentrations were measured on days 0, 4, 7, 14, 21, and 28, and nitrite depletion rate was estimated by using first-order kinetics. The response surface methodology was used to model L. monocytogenes lag time and growth rate based on ingoing nitrite, ascorbate, and the residual nitrite remaining at the point of inoculation. Modeling results showed that lag time was impacted by residual nitrite concentration remaining at inoculation, as well as the squared term of ingoing nitrite, whereas growth rate was affected by ingoing nitrite concentration but not by the remaining residual nitrite at the point of inoculation. Residual nitrite depletion rate was dependent upon ingoing nitrite concentration and was only slightly affected by ascorbate concentration. This study confirmed that ingoing nitrite concentration influences L. monocytogenes growth in RTE products, yet residual nitrite concentration contributes

  8. Antimicrobial Tolerance in Listeria monocytogenes

    DEFF Research Database (Denmark)

    Curtis, Thomas Darwin

    There are two ways in which bacteria survive killing by antibiotics. The most well-known, is antibiotic resistance, which results from the acquisition of a resistance gene or mutation that allows bacteria to grow and divide in the presence of antibiotic concentrations that would normally kill other...... that are completely refractory to antibiotics due to the inactivity of cellular processes. Persister cells have been linked to treatment failures in several bacterial infections including Mycobacterium tuberculosis, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. Preceding the start of this Ph......D project, Listeria monocytogenes was observed to form these antibiotic tolerant persister cells. L. monocytogenes is a Gram-positive, foodborne pathogen that causes listeriosis, a rare, but often lethal disease, even with antibiotic treatment. It typically affects pregnant women, neonates, the elderly...

  9. Modelling the growth of Listeria monocytogenes in fresh green coconut (Cocos nucifera L.) water.

    Science.gov (United States)

    Walter, Eduardo H M; Kabuki, Dirce Y; Esper, Luciana M R; Sant'Ana, Anderson S; Kuaye, Arnaldo Y

    2009-09-01

    The behaviour of Listeria monocytogenes in the fresh coconut water stored at 4 degrees C, 10 degrees C and 35 degrees C was studied. The coconut water was aseptically extracted from green coconuts (Cocos nucifera L.) and samples were inoculated in triplicate with a mixture of 5 strains of L. monocytogenes with a mean population of approximately 3 log(10) CFU/mL. The kinetic parameters of the bacteria were estimated from the Baranyi model, and compared with predictions of the Pathogen Modelling Program so as to predict its behaviour in the beverage. The results demonstrated that fresh green coconut water was a beverage propitious for the survival and growth of L. monocytogenes and that refrigeration at 10 degrees C or 4 degrees C retarded, but did not inhibit, growth of this bacterium. Temperature abuse at 35 degrees C considerably reduced the lagtimes. The study shows that L. monocytogenes growth in fresh green coconut water is controlled for several days by storage at low temperature, mainly at 4 degrees C. Thus, for risk population this product should only be drunk directly from the coconut or despite the sensorial alterations should be consumed pasteurized.

  10. Effect of salts of organic acids on Listeria monocytogenes, shelf life, meat quality, and consumer acceptability of beef frankfurters.

    Science.gov (United States)

    Morey, Amit; Bowers, Jordan W J; Bauermeister, Laura J; Singh, Manpreet; Huang, Tung-Shi; McKee, Shelly R

    2014-01-01

    The objective of this study was to evaluate anti-listerial efficacy of salts of organic acids, and their impact on the quality of frankfurters. Beef frankfurters were manufactured by incorporating organic acids in 5 different combinations: (1) control (no marinade addition; C); (2) sodium lactate (2% wt/wt; SL); (3) potassium lactate (2% wt/wt; PL); (4) sodium citrate (0.75% wt/wt; SC); and (5) sodium lactate (2% wt/wt)/sodium diacetate (0.25% wt/wt; SL/SD). Cooked frankfurters were inoculated with streptomycin-resistant (1500 μg/mL) L. monocytogenes (7 log₁₀ CFU/frank). Inoculated and noninoculated frankfurters were vacuum packaged and stored at 4 °C. Samples were taken weekly up to 10 wk for estimation of L. monocytogenes as well as aerobic plate count (APC) and psychrotrophs (PSY), respectively. Total of 2 independent trials of the entire experiment were conducted. Noninoculated beef frankfurters were evaluated weekly by untrained sensory panelists for 7 wk. SL, PL, and SC treatments did not (P > 0.05) adversely affect consumer acceptability through 8 wk although, SL/SD treatment was significantly (P ≤ 0.05) less preferred across all sensory attributes. SL/SD treatment negatively affected product quality, but was able to control APC, PSY, and L. monocytogenes levels. SC performed similar to the control throughout the 8, 9, and 10 wk storage periods, providing no benefit for inhibiting L. monocytogenes (increasing from 7 logs CFU/frank to 10 logs CFU/frank throughout storage) or extending shelf life of the beef frankfurters. In conclusion, 2% SL and PL, and 2% SL/0.25% SD may be effective L. monocytogenes inhibitors (maintaining inoculation levels of 7 logs CFU/frank during storage), but changes in SL/SD treatment formulation should be studied to improve product quality.

  11. Exposure to minimally processed pear and melon during shelf life could modify the pathogenic potential of Listeria monocytogenes.

    Science.gov (United States)

    Colás-Medà, Pilar; Viñas, Inmaculada; Oliveira, Márcia; Anguera, Marina; Serrano, Jose C E; Abadias, Maribel

    2017-04-01

    Survival and virulence of foodborne pathogens can be influenced by environmental factors such as the intrinsic properties of food as well as the extrinsic properties that contribute to food shelf life (e.g., temperature and gas atmosphere). The direct contribution of food matrix characteristics on the survival of L. monocytogenes during fresh-cut fruit shelf life is not very well understood. In addition, the gastrointestinal tract is the primary route of listeriosis infection and penetration of the intestinal epithelial cell barrier is the first step in the infection process. Hence, the pathogenic potential of L. monocytogenes, measured as the capability for the organism to survive a simulated gastrointestinal tract and the proportion of cells able to subsequently adhere to and invade differentiated Caco-2 cells, subjected to fresh-cut pear and melon shelf life, was investigated. Samples were inoculated, stored at 10 °C for 7 days and evaluated after inoculation and again after 2 and 7 days of storage. A decrease in L. monocytogenes' capacity to survive a simulated gastrointestinal tract was observed with increasing storage time, regardless of the fruit matrix evaluated. Furthermore, L. monocytogenes placed on fresh-cut pear and melon was subjected to an attachment and invasion assay after crossing the simulated gastrointestinal tract. After inoculation, pathogen on fresh-cut pear showed 5-fold more capacity to adhere to Caco-2 cells than pathogen on fresh-cut melon. After 2 days of storage, L. monocytogenes grown on fresh-cut melon showed similar adhesive capacity (1.11%) than cells grown on pear (1.83%), but cells grown on melon had the higher invasive capacity (0.0093%). We can conclude that minimally processed melon could represent a more important hazard than pear under the studied shelf life. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. High-pressure processing and antimicrobial biodegradable packaging to control Listeria monocytogenes during storage of cooked ham.

    Science.gov (United States)

    Marcos, Begonya; Aymerich, Teresa; Monfort, Josep M; Garriga, Margarita

    2008-02-01

    The efficiency of combining high-pressure processing (HPP) and active packaging technologies to control Listeria monocytogenes growth during the shelf life of artificially inoculated cooked ham was assessed. Three lots of cooked ham were prepared: control, packaging with alginate films, and packaging with antimicrobial alginate films containing enterocins. After packaging, half of the samples were pressurized. Sliced cooked ham stored at 6 degrees C experienced a quick growth of L. monocytogenes. Both antimicrobial packaging and pressurization delayed the growth of the pathogen. However, at 6 degrees C the combination of antimicrobial packaging and HPP was necessary to achieve a reduction of inoculated levels without recovery during 60 days of storage. Further storage at 6 degrees C of pressurized antimicrobial packed cooked ham resulted in L. monocytogenes levels below the detection limit (day 90). On the other hand, storage at 1 degrees C controlled the growth of the pathogen until day 39 in non-pressurized ham, while antimicrobial packaging and storage at 1 degrees C exerted a bacteriostatic effect for 60 days. All HPP lots stored at 1 degrees C led to counts <100CFU/g at day 60. Similar results were observed when combining both technologies. After a cold chain break no growth of L. monocytogenes was observed in pressurized ham packed with antimicrobial films, showing the efficiency of combining both technologies.

  13. Antimicrobial effects of essential oils, nisin, and irradiation treatments against Listeria monocytogenes on ready-to-eat carrots.

    Science.gov (United States)

    Ndoti-Nembe, Aude; Vu, Khanh Dang; Doucet, Nicolas; Lacroix, Monique

    2015-04-01

    The study aimed at using essential oil (EO) alone or combined EO with nisin and low dose γ-irradiation to evaluate their antibacterial effect against Listeria monocytogenes during storage of carrots at 4 °C. Minicarrots were inoculated with L. monocytogenes at a final concentration of approximately 7 log CFU/g. Inoculated samples were coated by nisin at final concentration of 10(3) International Unit (IU)/mL or individual mountain savory EO or carvacrol at final concentration of 0.35%, w/w) or nisin plus EO. The samples were then irradiated at 0, 0.5, and 1.0 kGy. The treated samples were kept at 4 °C and microbial analysis of samples were conducted at days 1, 3, 6, and 9. The results showed that coating carrots by carvacrol plus nisin or mountain savory plus nisin and then irradiating coated carrots at 1 kGy could reduce L. monocytogenes by more than 3 log at day 1 and reduced it to undetectable level from day 6. Thus, the combined treatments using nisin plus carvacrol or nisin plus mountain savory and irradiation at 1.0 kGy could be used as an effective method for controlling L. monocytogenes in minicarrots.

  14. Tensile properties of V-(4-5)Cr-(4-5)Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Nowicki, L.; Busch, D.; Smith, D.L. [Argonne National Laboratory, Chicago, IL (United States)

    1996-04-01

    The current focus of the U.S program of research on V-base alloys is on V-(4-5)Cr(4-5)Ti that contains 500-1000 wppm Si. in this paper, we present experimental results on baseline tensile properties of two laboratory-scale heats of this alloy and of a 500-kg production heat of V-4Cr-4Ti (heat 832665) that were measured at 23-700 C. Both the production- and laboratory scale heats of the reference alloy V-4Cr-4Ti exhibited excellent tensile properties at temperatures up to {approx}650{degrees}C.

  15. Microstructural examination of V-(4-5%) Cr-(4-5%)Ti irradiated in X530

    Energy Technology Data Exchange (ETDEWEB)

    Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States); Chung, H.M. [Argonne Natinonal Lab., IL (United States)

    1997-08-01

    Microstructural examination results are reported for two heats of V-(4-5%)Cr-(4-5%)Ti irradiated in the X530 experiment to {approximately}400{degrees}C to provide an understanding of the microstructural evolution that may be associated with degradation of mechanical properties. Fine precipitates were observed in high density intermixed with small defect clusters for all conditions examined following the irradiation. The irradiation-induced precipitation does not appear to be affected by preirradiation heat treatment at 950-1125{degrees}C. There was no evidence for a significant density of large (diameter >10 nm) dislocation loops or network dislocations.

  16. Thermophysical and mechanical properties of V-(4-5)%Cr-(4-5)%Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J. [Oak Ridge National Lab., TN (United States)

    1998-03-01

    Solid solution V-Cr-Ti alloys exhibit a good combination of high thermal conductivity, adequate tensile strength, and low thermal expansion. The key thermophysical and mechanical properties for V-(4-5)%Cr-(4-5)%Ti alloys are summarized in this report. Some of these data are available in the ITER Materials Properties Handbook (IMPH), whereas other data have been collected from recent studies. The IMPH is updated regularly, and should be used as the reference point for design calculations whenever possible.

  17. Atlas(®) Listeria monocytogenes LmG2 Detection Assay Using Transcription Mediated Amplification to Detect Listeria monocytogenes in Selected Foods and Stainless Steel Surface.

    Science.gov (United States)

    Bres, Vanessa; Yang, Hua; Hsu, Ernie; Ren, Yan; Cheng, Ying; Wisniewski, Michele; Hanhan, Maesa; Zaslavsky, Polina; Noll, Nathan; Weaver, Brett; Campbell, Paul; Reshatoff, Michael; Becker, Michael

    2014-01-01

    The Atlas Listeria monocytogenes LmG2 Detection Assay, developed by Roka Bioscience Inc., was compared to a reference culture method for seven food types (hot dogs, cured ham, deli turkey, chicken salad, vanilla ice cream, frozen chocolate cream pie, and frozen cheese pizza) and one surface (stainless steel, grade 316). A 125 g portion of deli turkey was tested using a 1:4 food:media dilution ratio, and a 25 g portion for all other foods was tested using 1:9 food:media dilution ratio. The enrichment time and media for Roka's method was 24 to 28 h for 25 g food samples and environmental surfaces, and 44 to 48 h for 125 g at 35 ± 2°C in PALCAM broth containing 0.02 g/L nalidixic acid. Comparison of the Atlas Listeria monocytogenes LmG2 Detection Assay to the reference method required an unpaired approach. For each matrix, 20 samples inoculated at a fractional level and five samples inoculated at a high level with a different strain of Listeria monocytogenes were tested by each method. The Atlas Listeria monocytogenes LmG2 Detection Assay was compared to the Official Methods of Analysis of AOAC INTERNATIONAL 993.12 method for dairy products, the U.S. Department of Agriculture, Food Safety and Inspection Service, Microbiology Laboratory Guidebook 8.08 method for ready-to-eat meat and environmental samples, and the U.S. Food and Drug Administration Bacteriological Analytical Manual, Chapter 10 method for frozen foods. In the method developer studies, Roka's method, at 24 h (or 44 h for 125 g food samples), had 126 positives out of 200 total inoculated samples, compared to 102 positives for the reference methods at 48 h. In the independent laboratory studies, vanilla ice cream, deli turkey and stainless steel grade 316 were evaluated. Roka's method, at 24 h (or 44 h for 125 g food samples), had 64 positives out of 75 total inoculated samples compared to 54 positives for the reference methods at 48 h. The Atlas Listeria monocytogenes LmG2 Detection Assay detected all 50

  18. Acidified sodium chlorite treatment for inhibition of Listeria monocytogenes growth on the surface of cooked roast beef.

    Science.gov (United States)

    Beverly, Richelle L; Janes, Marlene E; Oliver, Grady

    2006-02-01

    The effects of acidified sodium chlorite (ASC) against Listeria monocytogenes on the surface of cooked roast beef were investigated. L. monocytogenes, strain V7, serotype 1/2a, was inoculated at numbers of 6.0 log CFU/g onto 5-g cubes of cooked regular or spicy roast beef. The samples were allowed to air dry for 1 h. The cooked roast beef samples were dipped into ASC or sprayed with ASC solutions of 250, 500, 750, or 1,000 ppm, then placed in bags with or without a vacuum and refrigerated at 4 degrees C. L. monocytogenes counts were determined after 0, 7, 14, 21, and 28 days of storage by spread plating roast beef samples onto Oxford agar plates that were incubated at 37 degrees C for 48 h. At day 28, the number of L. monocytogenes on the > or = 500 ppm ASC-treated spicy roast beef samples had count reductions that were >4.0 log CFU/g, whereas the same concentrations of ASC-treated regular roast beef samples had approximately a 2.5 log CFU/g reduction in L. monocytogenes counts when compared with the untreated samples. No significant differences (P > 0.05) were observed in L. monocytogenes counts between the vacuum- or nonvacuum-packaged ASC-treated cooked roast beef samples. Sensory evaluation showed no significant differences (P > 0.05) between ASC-treated and untreated roast beef. ASC can be used as a processing aid in the form of a dip or spray treatment to control L. monocytogenes on the surface of cooked roast beef.

  19. Survival of Listeria monocytogenes during Production and ripening of traditional Turkish Savak tulum cheese and in synthetic gastric fluid.

    Science.gov (United States)

    Dikici, Abdullah; Calicioglu, Mehmet

    2013-10-01

    This study investigated the survival and acid tolerance of Listeria monocytogenes during the 2-day processing stage and 90-day ripening of Savak tulum cheese, a traditional cheese in Turkey. Experimental Savak tulum cheese was produced from raw sheep's milk that was inoculated with a L. monocytogenes mixture consisting of five strains (average 7.0 log CFU/ml) and was ripened at 6°C for 90 days. Microbiological and chemical analyses and acid exposure experiments in synthetic gastric fluid (SGF) (pH 1.5 to 2.5) were carried out on days 1 and 2 during processing and on days 0, 15, 30, 45, 60, and 90 during ripening. The numbers of L. monocytogenes did not decrease during processing, but a total of 4.1 log CFU/g reduction was observed during ripening. Throughout the ripening period, L. monocytogenes cells survived direct 90-min exposures of the cheese samples to SGF. These results suggest that, although the pathogen numbers decreased in Savak tulum cheese ripened at 6°C for 90 days, a sublethal environment may have occurred in the cheese during the production stage, activating the acid-tolerance mechanisms of the pathogen and allowing L. monocytogenes to maintain its viability in the SGF for 90 min.

  20. Inhibition of Listeria monocytogenes on Ready-to-Eat Meats Using Bacteriocin Mixtures Based on Mode-of-Action

    Directory of Open Access Journals (Sweden)

    Paul Priyesh Vijayakumar

    2017-03-01

    Full Text Available Bacteriocin-producing (Bac+ lactic acid bacteria (LAB comprising selected strains of Lactobacillus curvatus, Lactococcus lactis, Pediococcus acidilactici, and Enterococcus faecium and thailandicus were examined for inhibition of Listeria monocytogenes during hotdog challenge studies. The Bac+ strains, or their cell-free supernatants (CFS, were grouped according to mode-of-action (MOA as determined from prior studies. Making a mixture of as many MOAs as possible is a practical way to obtain a potent natural antimicrobial mixture to address L. monocytogenes contamination of RTE meat products (i.e., hotdogs. The heat resistance of the bacteriocins allowed the use of pasteurization to eliminate residual producer cells for use as post-process surface application or their inclusion into hotdog meat emulsion during cooking. The use of Bac+ LAB comprising 3× MOAs directly as co-inoculants on hotdogs was not effective at inhibiting L. monocytogenes. However, the use of multiple MOA Bac+ CFS mixtures in a variety of trials demonstrated the effectiveness of this approach by showing a >2-log decrease of L. monocytogenes in treatment samples and 6–7 log difference vs. controls. These data suggest that surface application of multiple mode-of-action bacteriocin mixtures can provide for an Alternative 2, and possibly Alternative 1, process category as specified by USDA-FSIS for control of L. monocytogenes on RTE meat products.

  1. Effect of Leuconostoc mesenteroides 11 bacteriocin in the multiplication control of Listeria monocytogenes 4b Efeito da bacteriocina de Leuconostoc mesenteroides 11 no controle da multiplicação de Listeria monocytogenes 4b

    OpenAIRE

    Rafael C.R. Martinez; Martinis,Elaine C. P. De

    2006-01-01

    The activity of a crude preparation of bacteriocin produced by the chicken meat isolate Leuconostoc mesenteroides 11, was evaluated at 8ºC and 15ºC against Listeria monocytogenes. The pathogen was inoculated in a crude preparation of the bacteriocin and its population was enumerated after 0.5 and 10 days. The title of the bacteriocin in the preparation was determined immediately before inoculation and after 10 days of incubation at both temperatures. As a negative control, a non-bacteriocin p...

  2. Effect of monolaurin and lactic acid on Listeria monocytogenes attached to catfish fillets.

    Science.gov (United States)

    Verhaegh, E G; Marshall, D L; Oh, D H

    1996-04-01

    The purpose of this study was to determine the effects of monolaurin and lactic acid, singly or combined, on Listeria monocytogenes attached to catfish fillets. Skinless catfish fillets were inoculated with L. monocytogenes and dip treated in monolaurin and/or lactic acid solution for various time periods. Results showed that monolaurin up to 400 micrograms/ml had no influence on counts. Conversely, lactic acid-treated fillets had reduced counts compared to controls. Dipping in 0.85, 1.70, or 2.55% lactic acid for 30 min reduced counts by 0.9, 1.4, or 1.3 logs, respectively. Extending the dipping time to 60 min resulted in little additional decrease in counts. Combining monolaurin with lactic acid yielded results similar to lactic acid alone. Hence, population reduction ability resides with lactic acid and not monolaurin.

  3. Comparative evaluation of the VIDAS Listeria monocytogenes Xpress (LMX) for the detection of Listeria monocytogenes in a variety of foods.

    Science.gov (United States)

    Johnson, Ronald; Mills, John; Pittet, Jean-Louis; Hughes, Denise

    2013-01-01

    The VIDAS Listeria monocytogenes Xpress (LMX) test is an enzyme-linked fluorescent immunoassay designed for use with the automated VIDAS or mini-VIDAS instruments for the specific detection of L. monocytogenes using a 26 h proprietary enrichment broth. The VIDAS LMX method was validated according to harmonized AOAC Research Institute (RI) and Official Methods of Analysis guidelines in both the AOAC Performance Tested Method (PTM) and GovVal programs. In the PTM comparison studies, the VIDAS LMX method was compared to the U.S. Department of Agriculture-Food Safety and Inspection Service Microbiology Laboratory Guidebook, the U.S. Food and Drug Administration Bacteriological Analytical Manual, and AOAC Official Methods. The comparative food studies consisted of two main parts: internal testing and AOAC independent laboratory testing, which included seven food matrixes (deli ham, processed cheese, vanilla ice cream, cooked shrimp, smoked white fish, frozen spinach, and peanut butter). As part of the AOAC R1 GovVal program, the VIDAS LMX method was compared to the Health Canada MFHPB-30 method for the detection of L. monocytogenes in five ready-to-eat (RTE) meats (hot dogs, deli turkey, deli ham, fermented sausage, and liver paté). Twenty replicates of each inoculation level and five uninoculated controls were evaluated in each study. The LMX method also included the use ofchromogenic media, chromID Ottaviani Agosti agar and chromID L. mono. agar, for confirmation of LMX presumptive results. In both the PTM and GovVal evaluations, there were no significant differences in the Chi-square values for the LMX method when compared to reference methods. The additional parameters tested in the PTM evaluation (inclusivity, exclusivity, ruggedness, stability, and lot-to-lot) satisfied the AOAC RI performance requirements. In both the PTM and GovVal validation studies, the VIDAS LMX method demonstrated reliability as a rapid qualitative method for next-day detection of L

  4. Microstructural examination of irradiated V-(4-5%)Cr-(4-5%)Ti

    Energy Technology Data Exchange (ETDEWEB)

    Gelles, D.S. [Pacific Northwest National Lab., Richland, WA (United States); Rice, P.M.; Zinkle, S.J. [Oak Ridge National Lab., TN (United States); Chung, H.M. [Argonne National Lab., IL (United States)

    1998-03-01

    Microstructural examination results are reported for two heats of V-(4-5%)Cr-(4-5%)Ti irradiated in the EBR-II X530 experiment to {approximately}4 dpa at {approximately}400 C to provide an understanding of the microstructural evolution that may be associated with degradation of mechanical properties. Fine precipitates were observed in high density intermixed with small defect clusters for all conditions examined following the irradiation. The irradiation-induced precipitation does not appear to b affected by preirradiation heat treatment at 950--1125 C. There was no evidence for a significant density of large (diameter >10 nm) dislocation loops or network dislocations. Analytical investigators successfully demonstrated that the precipitates were enriched in titanium, depleted in vanadium and contained no nitrogen.

  5. Listeria monocytogenes en comidas preparadas

    OpenAIRE

    Vila Brugalla, Montserrat

    2013-01-01

    Tradicionalmente Listeria monocytogenes no era considerado como un importante patógeno transmitido a través de los alimentos y, en consecuencia, no había recibido mucha atención por parte de la industria alimentaria. Los índices de listeriosis en la población humana siempre habían estado enormemente ensombrecidos por otras enfermedades transmitidas por los alimentos como la salmonelosis o la campilobacterosis, y la confirmación de brotes era poco frecuente. Sin embargo, los brotes de listerio...

  6. Use of antimicrobial biodegradable packaging to control Listeria monocytogenes during storage of cooked ham.

    Science.gov (United States)

    Marcos, Begonya; Aymerich, Teresa; Monfort, Josep M; Garriga, Margarita

    2007-11-30

    The antimicrobial effect against L. monocytogenes of biodegradable films (alginate, zein and polyvinyl alcohol) containing enterocins was investigated. Survival of the pathogen was studied by means of challenge tests performed at 6 degrees C during 8 and 29 days, for air-packed and vacuum-packed sliced cooked ham, respectively. Air packaging was tested with two concentrations of enterocins (200 and 2000 AU/cm2). Control air-packed cooked ham showed an increase of L. monocytogenes from 10(4) to 10(7) CFU/g after 8 days. By contrast, packaging with antimicrobial films effectively slowed down the pathogen's growth, leading to final counts lower than in control lots. Air-packaging with alginate films containing 2000 AU/cm2 of enterocins effectively controlled L. monocytogenes for 8 days. An increase of only 1 log unit was observed in zein and polyvinyl alcohol lots at the same enterocin concentration. Vacuum packaging with films containing enterocins (2000 AU/cm2) also delayed the growth of the pathogen. No increase from inoculated levels was observed during 15 days in antimicrobial alginate films. After 29 days of storage, the lowest counts were obtained in samples packed with zein and alginate films containing enterocins, as well as with zein control films. The most effective treatment for controlling L. monocytogenes during 6 degrees C storage was vacuum-packaging of sliced cooked ham with alginate films containing 2000 AU/cm2 of enterocins. From the results obtained it can concluded that antimicrobial packaging can improve the safety of sliced cooked ham by delaying and reducing the growth of L. monocytogenes.

  7. Listeria monocytogenes inhibition by defatted mustard meal-based edible films.

    Science.gov (United States)

    Lee, Hahn-Bit; Noh, Bong Soo; Min, Sea C

    2012-02-01

    An antimicrobial edible film was developed from defatted mustard meal (Sinapis alba) (DMM), a byproduct from the bio-fuel industry, without incorporating external antimicrobials and its antimicrobial activity against Listeria monocytogenes and physical properties were investigated. The DMM colloidal solution consisting of 184 g water, 14 g DMM, and 2g glycerol was homogenized and incubated at 37°C for 0.2, 0.5, 24 or 48 h to prepare a film-forming solution. The pH of a portion of the film-forming solution (pH 5.5) was adjusted to 2.0 or 4.0. Films were formed by drying the film-forming solutions at 23°C for 48 h. The film-forming solution incubated for 48 h inhibited L. monocytogenes in broth and on agar media. Antimicrobial effects of the film prepared from the 48 h-incubated solution increased with decrease in pH of the solution from 5.5 to 2.0. The film from the film forming solution incubated for 48 h (pH 2.0) initially inhibited more than 4.0 log CFU/g of L. monocytogenes inoculated on film-coated salmon. The film-coating retarded the growth of L. monocytogenes in smoked salmon at 5, 10, and 15°C and the antimicrobial effect during storage was more noticeable when the coating was applied before inoculation than when it was applied after inoculation. The tensile strength, percentage elongation, solubility in watercxu, and water vapor permeability of the anti microbial film were 2.44 ± 0.19 MPa, 6.40 ± 1.13%, 3.19 ± 0.90%, and 3.18 ± 0.63 gmm/kPa hm(2), respectively. The antimicrobial DMM films have demonstrated a potential to be applied to foods as wraps or coatings to control the growth of L. monocytogenes.

  8. The effect of high hydrostatic pressure, sodium nitrite and salt concentration on the growth of Listeria monocytogenes on RTE ham and turkey.

    Science.gov (United States)

    Myers, Kevin; Montoya, Damian; Cannon, Jerry; Dickson, James; Sebranek, Joseph

    2013-02-01

    Growth of Listeria monocytogenes was evaluated for up to 182 days after inoculation on ready-to-eat (RTE) sliced ham and turkey breast formulated with sodium nitrite (0 or 200 ppm), sodium chloride (1.8% or 2.4%), and treated (no treatment or 600 MPa) with high hydrostatic pressure (HHP). HHP at 600 MPa for 3 min resulted in a 3.85-4.35 log CFU/g reduction in L. monocytogenes. With formulations at similar proximate analyses, one of the evaluation days (day 21) without HHP showed significantly greater growth of L. monocytogenes in ham than in turkey breast, but there were no significant differences on other evaluation days or with HHP. There were no differences in growth of L. monocytogenes due to sodium chloride level. Sodium nitrite provided a small, but significant inhibition of L. monocytogenes without HHP, but addition of sodium nitrite did not significantly affect growth of L. monocytogenes with use of HHP. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Pro WPF 4.5 in C# Windows Presentation Foundation in .NET 4.5

    CERN Document Server

    MacDonald, Matthew

    2012-01-01

    Microsoft's Windows Presentation Foundation (WPF) provides you with a development framework for building high-quality user experiences for the Windows operating system. It blends together rich content from a wide range of sources and allows you unparalleled access to the processing power of your Windows computer. Pro WPF 4.5 in C# provides a thorough, authoritative guide to how WPF really works. Packed with no-nonsense examples and practical advice you'll learn everything you need to know in order to use WPF in a professional setting. The book begins by building a firm foundation of elementary

  10. Molecular characterization and antibiogram of Listeria monocytogenes isolated from chicken and mutton of retail markets

    Directory of Open Access Journals (Sweden)

    Vinay Kumar B. N., Nadeem Fairoze , Madhavaprasad C. B.

    2016-06-01

    Full Text Available Objective: To isolate Listeria monocytogenes from chicken and mutton meat sold at retail outlets and to characterize isolates for virulence determinants. Methods: Listeria monocytogenes was isolated from chicken and mutton meat samples using ISO: 11290 method. Multiplex PCR was performed for the detection of virulence associated genes. Results: Out of 198 retail meat samples (72 chicken and 126 mutton analyzed, Listeria monocytogenes was isolated from 4.5% (8.3% chicken and 2.3% mutton samples. All the 9 isolates (6 from chicken and 3 from mutton belonged to 1/2a servar and carried virulence genes viz. haemolysin (hlyA, phosphatidylinositol phospholipase (plcA, actin polymerization protein (actA and invasive associative protein p60 (Iap. Conclusion: L. monocytogenes is an organism of food safety and public health significance, its recovery from the meat sold at retail outlets indicated breach in the quality assurance. J Microbiol Infect Dis 2016;6(2: 65-68

  11. Growth Potential of Listeria Monocytogenes in Sliced Turkey Bresaola Packed in Modified Atmosphere

    Science.gov (United States)

    Cosciani-Cunico, Elena; D’Amico, Stefano; Sfameni, Chiara; Bertasi, Barbara; Losio, Marina N.; Serraino, Andrea; Daminelli, Paolo

    2014-01-01

    According to EC Regulation No 2073/2005, for food business operators that produce ready-to-eat (RTE) product, it is crucial to be able to demonstrate if the product supports the growth of Listeria monocytogenes. The objective of the study was therefore to evaluate the behaviour of L. monocytogenes in sliced RTE turkey bresaola (made by cured turkey breast 4.5% NaCl, 1% sodium lactate, sodium nitrite 150 ppm and flavouring) during the shelf life of the product, simulating a contamination during the slicing operation. Considering a shelf life of 90 days, as defined by manufacturer, the packages of sliced bresaola were stored at 5°C for 7 days and at 8°C for the remaining storage time (83 days). L. monocytogenes count decreased during storage test from 1.43/1.98 log cfu/g in the three batches tested to 1.03 log cfu/g in one batch and to undetectable levels in the other two batches. The results show that the investigated product is unable to support the growth of L. monocytogenes. PMID:27800323

  12. Adaptive growth responses of Listeria monocytogenes to acid and osmotic shifts above and across the growth boundaries.

    Science.gov (United States)

    Belessi, C-I A; Le Marc, Y; Merkouri, S I; Gounadaki, A S; Schvartzman, S; Jordan, K; Drosinos, E H; Skandamis, P N

    2011-01-01

    The effect of acid and osmotic shifts on the growth of Listeria monocytogenes was evaluated at 10°C. Two types of shifts were tested: (i) within the range of pH and water activity (a(w)) levels that allow growth of L. monocytogenes and (ii) after habituation at no-growth conditions back to growth-permitting conditions. A L. monocytogenes cheese isolate, with high survival capacity during cheesemaking, was inoculated (10(2) CFU/ml) in tryptic soy broth supplemented with 0.6% yeast extract at six pH levels (5.1 to 7.2; adjusted with lactic acid) and 0.5% NaCl (a(w) 0.995), or four a(w) levels (0.995 to 0.93, adjusted with 0.5 to 10.5% NaCl) at pH 7.2 and grown to early stationary phase. L. monocytogenes was then shifted (at 10(2) CFU/ml) to each of the aforementioned growth-permitting pH and a(w) levels and incubated at 10°C. Shifts from no-growth to growth-permitting conditions were carried out by transferring L. monocytogenes habituated at pH 4.9 or a(w) 0.90 (12.5% NaCl) for 1, 5, and 10 days to all pH and a(w) levels permitting growth. Reducing a(w) or pH at different levels in the range of 0.995 to 0.93 and 7.2 to 5.1, respectively, decreased the maximum specific growth rate of L. monocytogenes. The lag time of the organism increased with all osmotic downshifts, as well as by the reduction of pH to 5.1. Conversely, any type of shift within pH 5.5 to 7.2 did not markedly affect the lag times of L. monocytogenes. The longer the cells were incubated at no-growth a(w) (0.90), the faster they initiated growth subsequently, suggesting adaptation to osmotic stress. Conversely, extended habituation at pH 4.9 had the opposite effect on subsequent growth of L. monocytogenes, possibly due to cell injury. These results suggest that there is an adaptation or injury rate induced at conditions inhibiting the growth of the pathogen. Thus, quantifying adaptation phenomena under growth-limiting environments, such as in fermented dairy and meat products or products preserved in

  13. Effect of packaging and storage time on survival of Listeria monocytogenes on kippered beef steak and turkey tenders.

    Science.gov (United States)

    Uppal, Kamaldeep K; Getty, Kelly J K; Boyle, Elizabeth A E; Harper, Nigel M; Lobaton-Sulabo, April Shayne S; Barry, Bruce

    2012-01-01

    The objective of our study was to determine effect of packaging method and storage time on reducing Listeria monocytogenes in shelf-stable meat snacks. Commercially available kippered beef steak strips and turkey tenders were dipped into a 5-strain L. monocytogenes cocktail, and dried at 23 °C until a water activity of 0.80 was achieved. Inoculated samples were packaged with 4 treatments: (1) vacuum, (2) nitrogen flushed with oxygen scavenger, (3) heat sealed with oxygen scavenger, and (4) heat sealed without oxygen scavenger. Samples were stored at 23 °C and evaluated for L. monocytogenes levels at 0, 24, 48, and 72 h. Initial levels (time 0) of L. monocytogenes were approximately 5.7 log CFU/cm² for steak and tenders. After 24 h of storage time, a 1 log CFU/cm² reduction of L. monocytogenes was observed for turkey tenders for all packaging treatments. After 48 h, turkey tenders showed >1 log CFU/cm² reduction of L. monocytogenes for all packaging treatments except for vacuum, where only 0.9 log CFU/cm² reduction was observed. After 72 h, reductions for all packaging treatments for turkey tenders ranged from 1.5 to 2.4 log CFU/cm². For kippered beef steak, there was no interaction between the packaging treatments and all storage times (P > 0.05) whereas, time was different (P packaging treatments and a 2.1 log CFU/ cm² L. monocytogenes reduction at 72 h of storage time. Processors of kippered beef steak and turkey tenders could use a combination of vacuum or nitrogen-flushing or heat sealed with an oxygen scavenger packaging methods and a holding time of 24 h prior to shipping to reduce potential L. monocytogenes numbers by ≥1 log. However, processors should be encouraged to hold packaged product a minimum of 72 h to enhance the margin of safety for L. monocytogenes control. © 2011 Institute of Food Technologists®

  14. Antibiotic therapy for Listeria monocytogenes bacteremia.

    Science.gov (United States)

    Hung, C C; Chang, S C; Chen, Y C; Hsieh, W C; Luh, K T

    1995-01-01

    Listeria monocytogenes has been recognized as an important pathogen in immunocompromised patients, but it has been rarely reported in Taiwan. We reviewed 13 cases of L. monocytogenes bacteremia at National Taiwan University Hospital over a 12-year period. All of the patients had underlying diseases. Fever was the most common presenting symptom, and neurologic signs were found in 6 patients. Most of the patients received penicillin G, ampicillin or piperacillin with an aminoglycoside. Corticosteroids were used in 9 of 13 patients. The overall mortality directly due to L. monocytogenes bacteremia was 31%. However, patients treated with cephalosporins or oxacillin had higher mortality than those treated with penicillin G, ampicillin or piperacillin (p = 0.05). Given the increasing number of immunosuppressed patients in Taiwan, it is likely that more cases will be encountered. Physicians in Taiwan should be aware of L. monocytogenes bacteremia and its treatment.

  15. Prevalence of Listeria monocytogenes in European cheeses

    DEFF Research Database (Denmark)

    Martinez Rios, Veronica; Dalgaard, Paw

    2017-01-01

    Both in Europe and worldwide cheese has caused important outbreaks of listeriosis and can be a vehicle for transmission of Listeria monocytogenes to consumers. A systematic review and meta-analysis were conducted using scientific literature and European Food Safety Authority (EFSA) reports...... understanding of L. monocytogenes prevalence in different types of cheeses and provided results that can be useful as input for quantitative microbiological risk assessment modelling....

  16. [Evaluation of the activity of probiotic cultures over Listeria monocytogenes during the production and storage of yogurt].

    Science.gov (United States)

    Berrocal, Darling; Arias, María Laura; Henderson, Marjorie; Wong, Eric

    2002-12-01

    The effect of probiotic cultures over Listeria monocytogenes during the production and storage of yogurt was evaluated. A yogurt mixture (10.6% non-fat solid liquids, 3% fat and 0.3% gelatin) was prepared, homogenized and pasteurized. Yogurt was inoculated with 0, 10(2), 10(4) and 10(6) CFU/mL of L. monocytogenes and 0.02% of traditional lactic culture YC 180 (Streptococcus thermophilus and Lactobacillus bulgaricus) and probiotic culture ABY-1 (Bifidobacterium longum, B. bifidum, B, infantis, Lactobacillus acidophilus, Streptococcus thermophilus y Lactobacillus delbrueckii subsp. bulgaricus). It was incubated for 3 h at 43 degrees C until pH reached an approximate value of 4.8, followed by refrigeration at 5 degrees C for 21 days. During fermentation, samples were taken every hour, and during storage every 3 days, analyzing pH and lactic, bifidobacteria and pathogen count for each time. It was demonstrated that there was no significant simple effect for the type of culture used (ABY-1 and YC 180) (p = 0.684) over the amount of L. monocytogenes present in yogurt during the fermentation and storage periods. The presence of bifidobacteria in the ABY-1 culture did not present a significant effect over L. monocytogenes. Neither the effect of time presented a significant effect over L. monocytogenes (p = 0.448). In this case, the ABY-1 and YC 180 cultures present a bacteriostatic effect over the pathogen. The probiotic cultures had a bacteriostatic but not bactericidal effect over L. monocytogenes. This is not related to the protective effect of these cultures in bowel, since in-vivo conditions favor the production of antimicrobial substances, such as bacteriocins that act over pathogens.

  17. Highly specific fiber optic immunosensor coupled with immunomagnetic separation for detection of low levels of Listeria monocytogenes and L. ivanovii

    Science.gov (United States)

    2012-01-01

    Background Immunomagnetic separation (IMS) and immunoassays are widely used for pathogen detection. However, novel technology platforms with highly selective antibodies are essential to improve detection sensitivity, specificity and performance. In this study, monoclonal antibodies (MAbs) against Internalin A (InlA) and p30 were generated and used on paramagnetic beads of varying diameters for concentration, as well as on fiber-optic sensor for detection. Results Anti-InlA MAb-2D12 (IgG2a subclass) was specific for Listeria monocytogenes and L. ivanovii, and p30-specific MAb-3F8 (IgM) was specific for the genus Listeria. At all bacterial concentrations (103–108 CFU/mL) tested in the IMS assay; the 1-μm diameter MyOne beads had significantly higher capture efficiency (P Listeria antibody (9 %). Furthermore, capture efficiency for MyOne-2D12 was highly specific for L. monocytogenes and L. ivanovii. Subsequently, we captured L. monocytogenes by MyOne-2D12 and MyOne-3F8 from hotdogs inoculated with mono- or co-cultures of L. monocytogenes and L. innocua (10–40 CFU/g), enriched for 18 h and detected by fiber-optic sensor and confirmed by plating, light-scattering, and qPCR assays. The detection limit for L. monocytogenes and L. ivanovii by the fiber-optic immunosensor was 3 × 102 CFU/mL using MAb-2D12 as capture and reporter antibody. Selective media plating, light-scattering, and qPCR assays confirmed the IMS and fiber-optic results. Conclusions IMS coupled with a fiber-optic sensor using anti-InlA MAb is highly specific for L. monocytogenes and L. ivanovii and enabled detection of these pathogens at low levels from buffer or food. PMID:23176167

  18. Listeria monocytogenes virulence factor Listeriolysin O favors bacterial growth in co-culture with the ciliate Tetrahymena pyriformis, causes protozoan encystment and promotes bacterial survival inside cysts

    Directory of Open Access Journals (Sweden)

    Ermolaeva Svetlana A

    2010-01-01

    Full Text Available Abstract Background The gram-positive pathogenic bacterium Listeria monocytogenes is widely spread in the nature. L. monocytogenes was reported to be isolated from soil, water, sewage and sludge. Listeriolysin O (LLO is a L. monocytogenes major virulence factor. In the course of infection in mammals, LLO is required for intracellular survival and apoptosis induction in lymphocytes. In this study, we explored the potential of LLO to promote interactions between L. monocytogenes and the ubiquitous inhabitant of natural ecosystems bacteriovorous free-living ciliate Tetrahymena pyriformis. Results Wild type L. monocytogenes reduced T. pyriformis trophozoite counts and stimulated encystment. The effects were observed starting from 48 h of co-incubation. On the day 14, trophozoites were eliminated from the co-culture while about 5 × 104 cells/ml remained in the axenic T. pyriformis culture. The deficient in the LLO-encoding hly gene L. monocytogenes strain failed to cause mortality among protozoa and to trigger protozoan encystment. Replenishment of the hly gene in the mutant strain restored toxicity towards protozoa and induction of protozoan encystment. The saprophytic non-haemolytic species L. innocua transformed with the LLO-expressing plasmid caused extensive mortality and encystment in ciliates. During the first week of co-incubation, LLO-producing L. monocytogenes demonstrated higher growth rates in association with T. pyriformis than the LLO-deficient isogenic strain. At latter stages of co-incubation bacterial counts were similar for both strains. T. pyriformis cysts infected with wild type L. monocytogenes caused listerial infection in guinea pigs upon ocular and oral inoculation. The infection was proved by bacterial plating from the internal organs. Conclusions The L. monocytogenes virulence factor LLO promotes bacterial survival and growth in the presence of bacteriovorous ciliate T. pyriformis. LLO is responsible for L. monocytogenes

  19. Influence of processing steps in cold-smoked salmon production on survival and growth of persistent and presumed non-persistent Listeria monocytogenes

    DEFF Research Database (Denmark)

    Porsby, Cisse Hedegaard; Vogel, Birte Fonnesbech; Mohr, Mona

    2008-01-01

    in a humidity chamber for 24 h. However, combining brining and liquid smoke with a drying (25 degrees C) step reduced the bacterium 10-100 fold over a 24 h period. Non-salted, brine injected or dry salted salmon fillets were surface inoculated with L. monocytogenes and cold-smoked in a pilot plant. L....... monocytogenes was reduced from 103 to 10-10(2) CFU/cm(2) immediately after cold-smoking. The greatest reductions were observed in dry salted and brine injected fillets as compared to cold-smoking of non-salted fresh fillets. Levels of L. monocytogenes decreased further when the cold-smoked fish was vacuum...

  20. Thermal inactivation of Listeria monocytogenes and Salmonella spp. in sous-vide processed marinated chicken breast.

    Science.gov (United States)

    Karyotis, Dimitrios; Skandamis, Panagiotis N; Juneja, Vijay K

    2017-10-01

    The heat resistance of a cocktail of five Salmonella strains and five L. monocytogenes strains was determined in teriyaki-marinated chicken breasts. Inoculated meat, packaged in bags, were completely immersed in a circulating water bath and cooked to a final temperature of 55, 57.5 or 60°C in 1h, and then held for predetermined times. The surviving Salmonella and L. monocytogenes cells were enumerated by surface plating on XLD agar and Palcam agar, respectively. D-values, determined by linear regression, of Salmonella in chicken breast ranged from 47.65min at 55°C to 7.48min at 60°C; the values for L. monocytogenes ranged from 54.81min at 55°C to 10.39min at 60°C. Marination rendered the pathogen more sensitive to the lethal effect of heat. The results of this study will assist the food industry in ensuring microbiological safety of sous-vide processed marinated chicken breasts. Published by Elsevier Ltd.

  1. Modeling the effect of temperature on survival rate of Listeria monocytogenes in yogurt.

    Science.gov (United States)

    Szczawiński, J; Szczawińska, M E; Łobacz, A; Jackowska-Tracz, A

    2016-01-01

    The aim of the study was to (i) evaluate the behavior of Listeria monocytogenes in a commercially produced yogurt, (ii) determine the survival/inactivation rates of L. monocytogenes during cold storage of yogurt and (iii) to generate primary and secondary mathematical models to predict the behavior of these bacteria during storage at different temperatures. The samples of yogurt were inoculated with the mixture of three L. monocytogenes strains and stored at 3, 6, 9, 12 and 15°C for 16 days. The number of listeriae was determined after 0, 1, 2, 3, 5, 7, 9, 12, 14 and 16 days of storage. From each sample a series of decimal dilutions were prepared and plated onto ALOA agar (agar for Listeria according to Ottaviani and Agosti). It was found that applied temperature and storage time significantly influenced the survival rate of listeriae (ppH value of the samples (pyogurt stored under temperature range from 3 to 15°C, however, the polynomial model gave a better fit to the experimental data.

  2. Behavior of Escherichia coli O157:H7 and Listeria monocytogenes during fermentation and storage of camel yogurt.

    Science.gov (United States)

    Al-Nabulsi, Anas A; Olaimat, Amin N; Osaili, Tareq M; Ayyash, Mutamed M; Abushelaibi, Aisha; Jaradat, Ziad W; Shaker, Reyad; Al-Taani, Mahmoud; Holley, Richard A

    2016-03-01

    In addition to its nutritional and therapeutic properties, camel milk has the ability to suppress the growth of a wide range of foodborne pathogens, but there is a lack of information regarding the behavior of these pathogens in products such as yogurt produced from camel milk. The objective of the current study was to investigate the behavior of Listeria monocytogenes and Escherichia coli O157:H7 during manufacture and storage of camel yogurt. Camel milk inoculated with L. monocytogenes and E. coli O157:H7 was fermented at 43° C for 5h using freeze-dried lactic acid bacteria (LAB) starter cultures (Streptococcus thermophilus and Lactobacillus bulgaricus) and stored at 4 or 10 °C for 14 d. Camel milk inoculated with L. monocytogenes and E. coli O157:H7 without starter culture was also prepared. During fermentation, the numbers of L. monocytogenes and E. coli O157:H7 increased 0.3 and 1.6 log cfu/mL, respectively, in the presence of LAB, and by 0.3 and 2.7 log cfu/mL in the absence of LAB. During storage at 4 or 10 °C, L. monocytogenes increased 0.8 to 1.2 log cfu/mL by 14 d in camel milk without LAB, but in the presence of LAB, the numbers of L. monocytogenes were reduced by 1.2 to 1.7 log cfu/mL by 14 d. Further, E. coli O157:H7 numbers in camel milk were reduced by 3.4 to 3.5 log cfu/mL in the absence of LAB, but E. coli O157:H7 was not detected (6.3 log cfu/mL reduction) by 7d in camel yogurt made with LAB and stored at either temperature. Although camel milk contains high concentrations of natural antimicrobials, L. monocytogenes was able to tolerate these compounds in camel yogurt stored at refrigerator temperatures. Therefore, appropriate care should be taken during production of yogurt from camel milk to minimize the potential for postprocess contamination by this and other foodborne pathogens.

  3. Effects of high pressure, subzero temperature, and pH on survival of Listeria monocytogenes in buffer and smoked salmon.

    Science.gov (United States)

    Ritz, M; Jugiau, F; Federighi, M; Chapleau, N; de Lamballerie, M

    2008-08-01

    High pressure processing is a novel food preservation technology, applied for over 15 years in the food industry to inactivate spoilage and pathogenic microorganisms. Many studies have shown the differential resistance of bacterial cells to high pressure. Listeria monocytogenes is a bacterium able to grow at refrigerated temperature and to survive for a long time in minimally processed foods such as raw smoked fish. The freezing process does not cause significant decline of L. monocytogenes. The phase diagram of water under pressure permits a pressure treatment under subzero temperature, without the disadvantages of freezing for food quality. The aim of this study was to estimate if combined effects of pressure and subzero temperature could increase the destruction of L. monocytogenes in buffer and in smoked salmon. We investigated effects of high pressure processing (100, 150, and 200 MPa) combined with subzero temperatures (-10, -14, and -18 degrees C) and pH (7.0 and 4.5). Results showed that the most effective high-pressure treatment to inactivate L. monocytogenes was 200 MPa, -18 degrees C, and pH 4.5. The relevance of pressure holding time and the synergistic effect of pressure coupled with the subzero temperature to inactivate bacteria are highlighted. Modifications of physical properties (color and texture) were a lightening of color and an increase of toughness, which might be accepted by consumers, since safety is increased.

  4. Effects of acidified sodium chlorite, cetylpyridinium chloride and hot water on populations of Listeria monocytogenes and Staphylococcus aureus on beef.

    Science.gov (United States)

    Ozdemir, H; Koluman, A; Yildirim, Y

    2006-08-01

    The present study was designed to determine the individual and combined effects of acidified sodium chlorite (ASC, 0.1%, 24 +/- 1 degrees C), cetylpyridinium chloride (CPC, 0.5%, 24 +/- 1 degrees C) and hot water (HW, 93 +/- 1 degrees C) treatments on the survival of Listeria monocytogenes and Staphylococcus aureus. Beef samples inoculated with L. monocytogenes and S. aureus were treated with nine different applications singly or in combination. Treatment groups comprised (i) untreated control; (ii) sterile tap water; (iii) 0.1% ASC; (iv) 0.5% CPC; (v) HW; (vi) HW followed by 0.1% ASC; (vii) HW followed by 0.5% CPC; (viii) 0.1% ASC followed by HW; (ix) 0.5% CPC followed by HW. Compared with the untreated control group, the reductions in L. monocytogenes populations were 1.14-2.31 log CFU g(-1), while the reductions in S. aureus populations were 0.83-2.74 log CFU g(-1) on day 0. The reduction effect that occurred after combined treatment with ASC followed by HW, HW followed by ASC, CPC followed by HW and HW followed by CPC was found to be significantly greater (P < 0.05) than after treatment with ASC and CPC alone on days 0, 2 and 4 of storage. ASC, CPC and HW treatments can be used to reduce L. monocytogenes and S. aureus, which would provide an additional measure of safety on the production line.

  5. Differential Listeria monocytogenes strain survival and growth in Katiki, a traditional Greek soft cheese, at different storage temperatures.

    Science.gov (United States)

    Kagkli, Dafni-Maria; Iliopoulos, Vassilios; Stergiou, Virginia; Lazaridou, Anna; Nychas, George-John

    2009-06-01

    Katiki Domokou is a traditional Greek cheese, which has received the Protected Designation of Origin recognition since 1994. Its microfloras have not been studied although its structure and composition may enable (or even favor) the survival and growth of several pathogens, including Listeria monocytogenes. The persistence of L. monocytogenes during storage at different temperatures has been the subject of many studies since temperature abuse of food products is often encountered. In the present study, five strains of L. monocytogenes were aseptically inoculated individually and as a cocktail in Katiki Domokou cheese, which was then stored at 5, 10, 15, and 20 degrees C. Pulsed-field gel electrophoresis was used to monitor strain evolution or persistence during storage at different temperatures in the case of the cocktail inoculum. The results suggested that strain survival of L. monocytogenes was temperature dependent since different strains predominated at different temperatures. Such information is of great importance in risk assessment studies, which typically consider only the presence or absence of the pathogen.

  6. Retardation of Listeria monocytogenes growth in mozzarella cheese using antimicrobial sachets containing rosemary oil and thyme oil.

    Science.gov (United States)

    Han, Jung H; Patel, Dhaval; Kim, Jung Eun; Min, Sea C

    2014-11-01

    An antimicrobial sachet containing microcellular foam starch (MFS) with embedded rosemary oil and thyme oil was developed to reduce bacterial growth in shredded mozzarella cheese. The efficacy of the volatiles of oils at various concentrations in reducing Listeria monocytogenes as well as the release of the oils from the MFS have been also determined in this study. The cheese, inoculated with a cocktail of 5 strains of L. monocytogenes (approximately 3 log CFU/g), was packaged in a Nylon/EVOH/PE bag. A paper sachet containing MFS embedded with rosemary oil and thyme oil, separately or together, was inserted into the bag. Rosemary and thyme oil volatiles released from the sachet restricted the growth of L. monocytogenes, resulting in a 2.5 log CFU/g reduction on day 9 at 10 °C. The volatile oils also showed inhibitory effects on the growth of lactic acid bacteria (LAB) and total aerobic bacteria (TAB). After 15 d at 10 °C, the numbers of LAB and TAB in the samples containing the sachet with both oils experienced a 1.2 and 1.4 log CFU/g reduction, respectively, compared to untreated samples. Nonetheless, the sachet treatment produced a distinct odor, unfavorably received by the panelists. The results suggest the potential for application of the sachet system for the reduction of growth of L. monocytogenes, LAB, and TAB in food products.

  7. Comparison of different application strategies of divergicin M35 for inactivation of Listeria monocytogenes in cold-smoked wild salmon.

    Science.gov (United States)

    Tahiri, I; Desbiens, M; Kheadr, E; Lacroix, C; Fliss, I

    2009-12-01

    Cold-smoked salmon treated with divergicin M35-producing Carnobacterium divergens M35, C. divergens ATCC 35677 (a non-producer of bacteriocin), purified divergicin M35 or supernatants of C. divergens M35 culture in snow crab hepatopancreas (SCH) medium or MRS broth was challenged with Listeria monocytogenes (up to 10(3) CFU/g). Samples were stored at 4 degrees C for up to four weeks. L. monocytogenes, total bacterial and lactic acid bacterial counts were determined along with changes in total volatile base nitrogen (TVBN) and biogenic amine production as well as texture, color and odor. A 2.6 log CFU/g reduction in L. monocytogenes was obtained for up to 10 days of storage in samples treated with C. divergens M35. Purified divergicin M35 (50 microg/g), SCH supernatant or MRS supernatant brought reductions of 1 log CFU/g at the beginning of storage. However, the anti-listerial activity of the supernatants lasted for 15 days compared to 3 days for purified divergicin M35. Color and texture were affected little in samples containing C. divergens M35 compared to un-inoculated samples. TVBN and biogenic amine production, particularly tyramine, remained below the maximum acceptable level in fish appreciation. These results clearly show the potential of C. divergens M35 culture as well as divergicin M35 bio-ingredient for application to the inactivation of L. monocytogenes in ready-to-eat seafood.

  8. Behavior of Listeria monocytogenes in Sliced Ready-to-Eat Meat Products Packaged under Vacuum or Modified Atmosphere Conditions.

    Science.gov (United States)

    Menéndez, Rosa Ana; Rendueles, Eugenia; Sanz, José Javier; Capita, Rosa; García-Fernández, Camino

    2015-10-01

    The objective of this research was to determine the behavior of Listeria monocytogenes in three types of sliced ready-to-eat meat products packaged under vacuum or modified atmosphere conditions and stored at three temperatures. Slices of about 25 g of chorizo (a fermented dry pork sausage), jamón (cured ham), and cecina (a salted, dried beef product) were inoculated with L. monocytogenes NCTC 11994. Slices were packaged in a vacuum or in a modified atmosphere (20% CO2, 80% N2). After packaging, samples were stored for 6 months at three temperatures: 3, 11, or 20°C. Microbiological analyses were performed after 0, 1, 7, 15, 30, 45, 90, and 180 days of storage. The type of meat product, the type of packaging, the temperature, and the day of storage all influenced microbial levels (P cecina samples, counts of L. monocytogenes increased from day 0 to day 1 of storage and then remained constant until day 90 of the study. These results may be of use for enhancing the safety of these ready-to-eat meat product types. Additional evaluation of the behavior of L. monocytogenes in cecina is needed.

  9. Effect of native microflora, waiting period, and storage temperature on Listeria monocytogenes serovars transferred from cantaloupe rind to fresh-cut pieces during preparation.

    Science.gov (United States)

    Ukuku, Dike O; Olanya, Modesto; Geveke, David J; Sommers, Christopher H

    2012-11-01

    The most recent outbreak of listeriosis linked to consumption of fresh-cut cantaloupes indicates the need to investigate the behavior of Listeria monocytogenes in the presence of native microflora of cantaloupe pieces during storage. Whole cantaloupes were inoculated with L. monocytogenes (10(8)-CFU/ml suspension) for 10 min and air dried in a biosafety cabinet for 1 h and then treated (unwashed, water washed, and 2.5% hydrogen peroxide washed). Fresh-cut pieces (∼3 cm) prepared from these melons were left at 5 and 10°C for 72 h and room temperature (20°C) for 48 h. Some fresh-cut pieces were left at 20°C for 2 and 4 h and then refrigerated at 5°C. Microbial populations of fresh-cut pieces were determined by the plate count method or enrichment method immediately after preparation. Aerobic mesophilic bacteria, yeast and mold of whole melon, and inoculated populations of L. monocytogenes on cantaloupe rind surfaces averaged 6.4, 3.3, and 4.6 log CFU/cm(2), respectively. Only H(2)O(2) (2.5%) treatment reduced the aerobic mesophilic bacteria, yeast and mold, and L. monocytogenes populations to 3.8, 0.9, and 1.8 log CFU/cm(2), respectively. The populations of L. monocytogenes transferred from melon rinds to fresh-cut pieces were below detection but were present by enrichment. Increased storage temperatures enhanced the lag phases and growth of L. monocytogenes. The results of this study confirmed the need to store fresh-cut cantaloupes at 5°C immediately after preparation to enhance the microbial safety of the fruit.

  10. Effect of Morphology of Instantaneous Inoculant on Inoculated Result of Melted Iron

    Institute of Scientific and Technical Information of China (English)

    SHENG Da

    2003-01-01

    The characteristics of some elements in inoculant were analyzed. The effect of the morphology of instantaneous inoculant on its melting velocity was studied. When the inoculants pass through the same sieve number, the volume and the ratio of surface area to volume are different. It is evident from the theoretical analysis and experiment under some conditions that the melting velocity of inoculant depends on the morphology of inoculant. The morphology of inoculant during production should be controlled carefully.

  11. Calcinated calcium killing of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on the surface of tomatoes.

    Science.gov (United States)

    Bari, M L; Inatsu, Y; Kawasaki, S; Nazuka, E; Isshiki, K

    2002-11-01

    This study was conducted to evaluate the efficacy of calcinated calcium, 200 ppm chlorine water (1% active chlorine), and sterile distilled water in killing Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on the surfaces of spot-inoculated tomatoes. Inoculated tomatoes were sprayed with calcinated calcium, chlorinated water, or sterile distilled water (control) and hand rubbed for 30 s. Populations of E coli O157:H7, Salmonella, and L. monocytogenes in the rinse water and in the residual (0.1% peptone) wash solution were determined. Treatment with 200 ppm chlorine and calcinated calcium resulted in 3.40- and 7.85-log10 reductions of E. coli O157:H7, respectively, and 2.07- and 7.36-log10 reductions of Salmonella, respectively. Treatment with 200 ppm chlorine and calcinated calcium reduced L monocytogenes numbers by 2.27 and 7.59 log10 CFU per tomato, respectively. The findings of this study suggest that calcinated calcium could be useful in controlling pathogenic microorganisms in fresh produce.

  12. Listeria monocytogenes infection in pregnancy and neonatal sepsis

    Directory of Open Access Journals (Sweden)

    Francesca Pascale

    2008-06-01

    Full Text Available Authors report a fatal neonatal sepsis caused by Listeria monocytogenes. While the diagnostic procedure aimed to identify the microrganism is described, it is emphasized the importance to recover Streptococcus agalactiae (GBS and L. monocytogenes by means of vaginal-rectal swab culture. The intrapartum screening for L. monocytogenes, by Polymerase Chain Reaction (PCR providing results in 75 minutes is also evaluated.

  13. Modelling and predicting the simultaneous growth of Listeria monocytogenes and psychrotolerant lactic acid bacteria in processed seafood and mayonnaise-based seafood salads.

    Science.gov (United States)

    Mejlholm, Ole; Dalgaard, Paw

    2015-04-01

    A new combined model for Listeria monocytogenes and psychrotolerant Lactobacillus spp. was constructed and evaluated for processed seafood and mayonnaise-based seafood salads. The new model was constructed by combining existing cardinal parameter models for L. monocytogenes and Lactobacillus spp. using the classical Jameson effect to model microbial interaction. Maximum population density (MPD) values of L. monocytogenes were accurately predicted in processed seafood with a known initial cell concentration of Lactobacillus spp. For these experiments, average MPD values of 4.5 and 4.3 log (cfu/g) were observed and predicted, respectively for L. monocytogenes. In seafood salads, growth of L. monocytogenes continued at a reduced growth rate after Lactobacillus sakei had reached their MPD. This growth pattern was successfully described by an expanded version of the classical Jameson effect model, but only for products with pH of 6.0 or higher. For seafood salads with pH below 6.0 the performance of the new model was unacceptable, primarily due to prediction of no-growth by L. monocytogenes when growth was actually observed. Within its range of applicability the new model can be valuable for risk assessment and risk management of processed seafood as well as for evaluating the compliance of products with the EU regulation for ready-to-eat foods. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Cleaning and disinfection of biofilms composed of Listeria monocytogenes and background microbiota from meat processing surfaces.

    Science.gov (United States)

    Fagerlund, Annette; Møretrø, Trond; Heir, Even; Briandet, Romain; Langsrud, Solveig

    2017-06-30

    Surfaces of food processing premises are exposed to regular cleaning and disinfection (C&D) regimes, using biocides that are highly effective against bacteria growing as planktonic cells. However, bacteria growing in surface associated communities (biofilms) are typically more tolerant towards C&D than their individual free cells counterparts, and survival of pathogens such as Listeria monocytogenes may be affected by interspecies interactions within biofilms. In this study, Pseudomonas and Acinetobacter were the most frequently isolated genera surviving on conveyor belts subjected to C&D in meat processing plants. In the laboratory, Pseudomonas, Acinetobacter and L. monocytogenes dominated the community both in suspensions and in biofilms formed on conveyor belts, when cultures were inoculated with eleven-genera cocktails of representative bacterial strains from the identified background flora. When biofilms were exposed to daily C&D cycles, mimicking treatments used in food industry, the levels of Acinetobacter and Pseudomonas mandelii diminished, and biofilms were instead dominated by Pseudomonas putida (65-76%), Pseudomonas fluorescens (11-15%) and L. monocytogenes (3-11%). The dominance of certain species after daily C&D correlated with high planktonic growth rates at 12°C and tolerance to C&D. In single-species biofilms, L. monocytogenes developed higher tolerance to C&D over time, both for the peracetic acid and quaternary ammonium disinfectant, indicating that a broad-spectrum mechanism was involved. Survival after C&D appeared to be a common property of L. monocytogenes strains, as both persistent and sporadic subtypes showed equal survival in complex biofilms. Biofilms established preferentially in surface irregularities of conveyor belts, potentially constituting harborage sites for persistent contamination.IMPORTANCE In food industry, efficient production hygiene is a key measure to avoid accumulation of spoilage bacteria and eliminate pathogens

  15. A novel model to assess the efficacy of steam surface pasteurization of cooked surimi gels inoculated with realistic levels of Listeria innocua.

    Science.gov (United States)

    Skåra, Torstein; Valdramidis, Vasilis P; Rosnes, Jan Thomas; Noriega, Estefanía; Van Impe, Jan F M

    2014-12-01

    Steam surface pasteurization is a promising decontamination technology for reducing pathogenic bacteria in different stages of food production. The effect of the artificial inoculation type and initial microbial load, however, has not been thoroughly assessed in the context of inactivation studies. In order to optimize the efficacy of the technology, the aim of this study was to design and validate a model system for steam surface pasteurization, assessing different inoculation methods and realistic microbial levels. More specifically, the response of Listeria innocua, a surrogate organism of Listeria monocytogenes, on a model fish product, and the effect of different inoculation levels following treatments with a steam surface pasteurization system was investigated. The variation in the resulting inoculation level on the samples was too large (77%) for the contact inoculation procedure to be further considered. In contrast, the variation of a drop inoculation procedure was 17%. Inoculation with high levels showed a rapid 1-2 log decrease after 3-5 s, and then no further inactivation beyond 20 s. A low level inoculation study was performed by analysing the treated samples using a novel contact plating approach, which can be performed without sample homogenization and dilution. Using logistic regression, results from this method were used to model the binary responses of Listeria on surfaces with realistic inoculation levels. According to this model, a treatment time of 23 s will result in a 1 log reduction (for P = 0.1).

  16. Inactivation of Escherichia coli O157:H7, Salmonella enteritidis, and Listeria monocytogenes on apples, oranges, and tomatoes by lactic acid with hydrogen peroxide.

    Science.gov (United States)

    Venkitanarayanan, Kumar S; Lin, Chia-min; Bailey, Hannalore; Doyle, Michael P

    2002-01-01

    The objective of this study was to develop a practical and effective method for inactivating or substantially reducing Escherichia coli O157:H7, Salmonella Enteritidis, and Listeria monocytogenes on apples, oranges, and tomatoes. Apples, oranges, and tomatoes were spot-inoculated with five-strain mixtures of E. coli O157:H7, Salmonella Enteritidis, and L. monocytogenes near the stem end and were submerged in sterile deionized water containing 1.5% lactic acid plus 1.5% hydrogen peroxide for 15 min at 40 degrees C. Inoculated samples treated with sterile deionized water at the same temperature and for the same duration served as controls. The bacterial pathogens on fruits subjected to the chemical treatment were reduced by >5.0 log10 CFU per fruit, whereas washing in deionized water decreased the pathogens by only 1.5 to 2.0 log10 CFU per fruit. Furthermore, substantial populations of the pathogens survived in the control wash water, whereas no E. coli O157:H7, Salmonella Enteritidis, or L. monocytogenes cells were detected in the chemical treatment solution. The sensory and qualitative characteristics of apples treated with the chemical wash solution were not adversely affected by the treatment. It was found that the treatment developed in this study could effectively be used to kill E. coli O157:H7, Salmonella Enteritidis, and L. monocytogenes on apples, oranges, and tomatoes at the processing or packaging level.

  17. Control of Listeria monocytogenes on frankfurters by dipping in hops beta acids solutions.

    Science.gov (United States)

    Shen, Cangliang; Geornaras, Ifigenia; Kendall, Patricia A; Sofos, John N

    2009-04-01

    Hops beta acids (HBA) are parts of hops flowers used in beer brewing and have shown antilisterial activity in bacteriological broth. The U.S. Department of Agriculture, Food Safety and Inspection Service has approved HBA for use to control Listeria monocytogenes on ready-to-eat meat products. This study evaluated the effects of HBA as dipping solutions to control L. monocytogenes during storage of frankfurters. Frankfurters (two replicates and three samples each) were inoculated (1.9 +/- 0.1 log CFU/cm2) with L. monocytogenes (10-strain mixture), dipped (2 min, 25 +/- 2 degrees C) in HBA solutions (0.03, 0.06, and 0.10%) or distilled water, and then vacuum packaged and stored at 4 or 10 degrees C for up to 90 and 48 days, respectively. Samples were periodically analyzed for microbial survival and growth on tryptic soy agar plus 0.6% yeast extract and PALCAM agar. Dipping in HBA solutions caused immediate L. monocytogenes reductions (P < 0.05) of 1.3 to 1.6 log CFU/cm2, whereas distilled water reduced counts by 1.0 log CFU/cm2. Pathogen growth was completely suppressed (P < 0.05) for 30 to 50 (4 degrees C) or 20 to 28 (10 degrees C) days on frankfurters dipped in HBA solutions, with antilisterial effects increasing with higher concentrations (0.03 to 0.10%). Fitting the data with the Baranyi model confirmed that the lag-phase duration of the pathogen was extended, and the growth rate was decreased on samples dipped in HBA solutions. Therefore, HBA may be considered for use to improve the microbial safety of ready-to-eat meat products, provided that future studies show no adverse effects on sensory qualities and that their use is economically feasible.

  18. Pediocin SA-1: A selective bacteriocin for controlling Listeria monocytogenes in maize silages.

    Science.gov (United States)

    Amado, Isabel R; Fuciños, Clara; Fajardo, Paula; Pastrana, Lorenzo

    2016-10-01

    In this study, we assessed the potential as silage additive of a bacteriocin produced by Pediococcus acidilactici Northern Regional Research Laboratory (NRRL) B-5627 (pediocin SA-1). Maize was inoculated either with a bacterial starter alone (I) or in combination with the bacteriocin (IP), and untreated silage served as control. We monitored the products of fermentation (ethanol, and lactic and acetic acids), the microbial population, and the presence of the indicator strain Listeria monocytogenes Colección Española de Cultivos Tipo (CECT) 4032 (1×10(5) cfu/g) after 1, 2, 5, 8, 16, and 30d of ensiling. Our results indicated antilisterial activity of the bacteriocin, anticipating the disappearance of L. monocytogenes in IP compared with I and control silages. The PCR-denaturing gradient gel electrophoresis analysis revealed the addition of the bacteriocin did not affect the bacterial communities of the spontaneous fermentation, and the inoculant-containing bacteria (Lactobacillus plantarum, Lactobacillus buchneri, and Enterococcus faecium) were found in addition to the bacterial communities of untreated maize silages in I and IP silages. Both treatments increased the concentration of antimicrobial compounds (acetic acid, ethanol, and 1,2-propanodiol) and led to lower residual sugar contents compared with the control, which would provide enhanced aerobic stability. The fact that the identified species L. plantarum, L. buchneri, and E. faecium produce some of these inhibitory compounds, together with their persistence throughout the 30d of fermentation, suggest these bacteria could actively participate in the ensiling process. According to these results, pediocin SA-1 could be used as an additive to control the presence of L. monocytogenes in maize silages selectively, while improving their fermentative quality and eventually their aerobic stability.

  19. Effect of inoculum size, bacterial species, type of surfaces and contact time to the transfer of foodborne pathogens from inoculated to non-inoculated beef fillets via food processing surfaces.

    Science.gov (United States)

    Gkana, E; Chorianopoulos, N; Grounta, A; Koutsoumanis, K; Nychas, G-J E

    2017-04-01

    The objective of the present study was to determine the factors affecting the transfer of foodborne pathogens from inoculated beef fillets to non-inoculated ones, through food processing surfaces. Three different levels of inoculation of beef fillets surface were prepared: a high one of approximately 10(7) CFU/cm(2), a medium one of 10(5) CFU/cm(2) and a low one of 10(3) CFU/cm(2), using mixed-strains of Listeria monocytogenes, or Salmonella enterica Typhimurium, or Escherichia coli O157:H7. The inoculated fillets were then placed on 3 different types of surfaces (stainless steel-SS, polyethylene-PE and wood-WD), for 1 or 15 min. Subsequently, these fillets were removed from the cutting boards and six sequential non-inoculated fillets were placed on the same surfaces for the same period of time. All non-inoculated fillets were contaminated with a progressive reduction trend of each pathogen's population level from the inoculated fillets to the sixth non-inoculated ones that got in contact with the surfaces, and regardless the initial inoculum, a reduction of approximately 2 log CFU/g between inoculated and 1st non-inoculated fillet was observed. S. Typhimurium was transferred at lower mean population (2.39 log CFU/g) to contaminated fillets than E. coli O157:H7 (2.93 log CFU/g), followed by L. monocytogenes (3.12 log CFU/g; P CFU/g) enhanced the transfer of bacteria to subsequent fillets compared to other materials (2.66 log CFU/g for SS and PE; P < 0.05). Cross-contamination between meat and surfaces is a multifactorial process strongly depended on the species, initial contamination level, kind of surface, contact time and the number of subsequent fillet, according to analysis of variance. Thus, quantifying the cross-contamination risk associated with various steps of meat processing and food establishments or households can provide a scientific basis for risk management of such products.

  20. Induction and stability of oxidative stress adaptation in Listeria monocytogenes EGD (Bug600) and F1057 in sublethal concentrations of H2O2 and NaOH.

    Science.gov (United States)

    De Abrew Abeysundara, Piumi; Nannapaneni, Ramakrishna; Soni, Kamlesh A; Sharma, Chander S; Mahmoud, Barakat

    2016-12-05

    Food processing and food handling environments may contain residual levels of sanitizers or cleaners which may trigger oxidative stress adaptation in Listeria monocytogenes. The aim of this study was to determine the induction and stability of oxidative stress adaptation in L. monocytogenes EGD (Bug600) (serotype 1/2a) and F1057 (serotype 4b) at different concentrations and times of sublethal oxidative stress induced by H2O2 or sublethal alkali stress induced by NaOH at 37°C. Both L. monocytogenes Bug600 and F1057 strains showed significantly higher survival in lethal oxidative stress (1000ppm H2O2) after pre-exposure to 50ppm H2O2 for 30min compared to control cells (no pre-exposure to H2O2). When the cells were pre-exposed to sublethal alkali stress by NaOH, the oxidative stress adaptation was induced within 5min in L. monocytogenes. The survival of both L. monocytogenes strains was increased by 2 to 4.5 logs in lethal oxidative stress when the cells were pre-exposed to sublethal alkali stress at pH9 from 5 to 120min by NaOH compared to control cells (no pre-exposure to sublethal alkali pH). Two other alkali reagents tested (KOH and NH4OH) also induced oxidative stress adaptation in L. monocytogenes. For both L. monocytogenes strains, the oxidative stress adaptation induced by sublethal H2O2 was reversible in 30min and that induced by sublethal alkali stress was reversible within 60min at 37°C in the absence of such sublethal stress. These findings show that sublethal oxidative or alkali stress conditions can induce oxidative stress adaptation that may increase the risk of survival of L. monocytogenes cells in lethal oxidative stress.

  1. Package systems and storage times serve as postlethality controls for Listeria monocytogenes on whole-muscle beef jerky and pork and beef smoked sausage sticks.

    Science.gov (United States)

    Lobaton-Sulabo, April Shayne S; Axman, Tyler J; Getty, Kelly J K; Boyle, Elizabeth A E; Harper, Nigel M; Uppal, Kamaldeep K; Barry, Bruce; Higgins, James J

    2011-02-01

    To validate how packaging and storage reduces Listeria monocytogenes on whole-muscle beef jerky and smoked pork and beef sausage sticks, four packaging systems (heat sealed [HS] without vacuum, heat sealed with oxygen scavenger, nitrogen flushed with oxygen scavenger [NFOS], and vacuum) and four ambient temperature storage times were evaluated. Commercially available whole-muscle beef jerky and smoked pork and beef sausage sticks were inoculated with a five-strain L. monocytogenes cocktail, packaged, and then stored at 25.5 °C until enumerated for L. monocytogenes at 0, 24, 48, and 72 h and 30 days after packaging. The interaction of packaging and storage time affected L. monocytogenes reduction on jerky, but not on sausage sticks. A >2-log CFU/cm(2) reduction was achieved on sausage sticks after 24 h of storage, regardless of package type, while jerky had 2 log CFU/cm(2), except for NFOS (1.22-log CFU/cm(2) reduction). Processors could package beef jerky in HS packages with oxygen scavenger or vacuum in conjunction with a 24-h holding time as an antimicrobial process to ensure a >1-log CFU/cm(2) L. monocytogenes reduction or use a 48-h holding time for HS- or NFOS-packaged beef jerky. A >3-log CFU/cm(2) mean reduction was observed for all beef jerky and sausage stick packaging systems after 30 days of 25.5 °C storage.

  2. Prevalence and growth of Listeria monocytogenes in naturally contaminated seafood

    DEFF Research Database (Denmark)

    Jørgensen, Lasse Vigel; Huss, Hans Henrik

    1998-01-01

    Listeria monocytogenes contamination of seafood varies with product category. The highest prevalence was found in cold- smoked fish (34-60%), while the lowest was found in heat- treated and cured seafood (4-12%). The prevalence of L. monocytogenes differed greatly in cold-smoked salmon between...... production sites, ranging from monocytogenes. The organism showed moderate growth...... in naturally contaminated cold-smoked, and 'gravad', fish while the growth appeared faster in hot smoked fish. Thus L. monocytogenes is not under control in these products. Finally, the prevalence and growth of L. monocytogenes in naturally contaminated cold-smoked salmon are discussed in relation...

  3. Prevalence and growth of Listeria monocytogenes in naturally contaminated seafood

    DEFF Research Database (Denmark)

    Jørgensen, Lasse Vigel; Huss, Hans Henrik

    1998-01-01

    Listeria monocytogenes contamination of seafood varies with product category. The highest prevalence was found in cold- smoked fish (34-60%), while the lowest was found in heat- treated and cured seafood (4-12%). The prevalence of L. monocytogenes differed greatly in cold-smoked salmon between...... production sites, ranging from monocytogenes. The organism showed moderate growth...... in naturally contaminated cold-smoked, and 'gravad', fish while the growth appeared faster in hot smoked fish. Thus L. monocytogenes is not under control in these products. Finally, the prevalence and growth of L. monocytogenes in naturally contaminated cold-smoked salmon are discussed in relation...

  4. Predicted and observed growth of Listeria monocytogenes in seafood challenge tests and in naturally contaminated cold smoked salmon

    DEFF Research Database (Denmark)

    Dalgaard, Paw; Jørgensen, Lasse Vigel

    1998-01-01

    with various types of seafoods. Storage trials clearly showed the growth of L. monocytogenes in naturally contaminated cold-smoked salmon to be markedly slower than growth in inoculated challenge tests. Consequently, all four models substantially overestimated growth in the naturally contaminated products......The performance of the Pathogen Modelling Program, the Food MicroModel, the Murphy-model and the Ross-model for growth of L. monocytogenes was evaluated by comparison with data from 100 seafood challenge tests and data from 13 storage trials with naturally contaminated sliced vacuum-packed cold-smoked....... Temperature, pH, NaCl/a(w) and lactate were measured in the storage trials and on the basis of these parameters, the Food MicroModel mu(max)-bias factor was 5.2. Clearly, the model could not be successfully validated with naturally contaminated cold-smoked salmon. To improve the applicability of predictive...

  5. Listeria monocytogenes survival in refrigerator dill pickles.

    Science.gov (United States)

    Kim, Jin Kyung; D'Sa, Elaine M; Harrison, Mark A; Harrison, Judy A; Andress, Elizabeth L

    2005-11-01

    Listeria monocytogenes can survive and grow in refrigerated foods with pH values of approximately 4.0 to 5.0 and salt concentrations of 3 to 4%. Home-fermented refrigerator dill pickles fit this description. Contamination of this product with L. monocytogenes could cause serious problems because these items are not heated prior to consumption. L. monocytogenes survival and growth patterns were investigated in refrigerator dill pickles at 1.3, 3.8, and 7.6% salt concentrations. Pickling cucumbers were dipped into an inoculum of L. monocytogenes, brine mixtures were added, and cucumbers were held at room temperature for 1 week and then refrigerated for up to 3 months. The pH, NaCl percentage, titratable acidity percentage, and total populations of Listeria and aerobic, psychrotrophic, and lactic acid bacteria were measured at the addition of brine, after 2, 4, and 7 days of storage at room temperature, and then weekly during refrigerated storage. The initial Listeria population was 5.4 to 5.6 log CFU/cm2 on cucumber surfaces and 3.9 to 4.6 log CFU/g internally. There was an approximate 0.3- to 1-log increase during room temperature fermentation followed by a population decline during refrigerator storage, with a greater decrease in the brines with the highest NaCl concentration. Up to 49 days, the internal tissue of pickles with 1.3, 3.8, or 7.6% salt concentrations were presumptively positive for L. monocytogenes by the enrichment method, and at 91 days the surfaces of such pickles were still positive for L. monocytogenes. Populations of total aerobes and lactic acid bacteria increased during room temperature storage and decreased gradually during refrigerated storage.

  6. Inoculation effects on root-colonizing arbuscular mycorrhizal fungal communities spread beyond directly inoculated plants.

    Science.gov (United States)

    Janoušková, Martina; Krak, Karol; Vosátka, Miroslav; Püschel, David; Štorchová, Helena

    2017-01-01

    Inoculation with arbuscular mycorrhizal fungi (AMF) may improve plant performance at disturbed sites, but inoculation may also suppress root colonization by native AMF and decrease the diversity of the root-colonizing AMF community. This has been shown for the roots of directly inoculated plants, but little is known about the stability of inoculation effects, and to which degree the inoculant and the inoculation-induced changes in AMF community composition spread into newly emerging seedlings that were not in direct contact with the introduced propagules. We addressed this topic in a greenhouse experiment based on the soil and native AMF community of a post-mining site. Plants were cultivated in compartmented pots with substrate containing the native AMF community, where AMF extraradical mycelium radiating from directly inoculated plants was allowed to inoculate neighboring plants. The abundances of the inoculated isolate and of native AMF taxa were monitored in the roots of the directly inoculated plants and the neighboring plants by quantitative real-time PCR. As expected, inoculation suppressed root colonization of the directly inoculated plants by other AMF taxa of the native AMF community and also by native genotypes of the same species as used for inoculation. In the neighboring plants, high abundance of the inoculant and the suppression of native AMF were maintained. Thus, we demonstrate that inoculation effects on native AMF propagate into plants that were not in direct contact with the introduced inoculum, and are therefore likely to persist at the site of inoculation.

  7. 41 CFR 60-4.5 - Hometown plans.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 1 2010-07-01 2010-07-01 true Hometown plans. 60-4.5...-CONSTRUCTION CONTRACTORS-AFFIRMATIVE ACTION REQUIREMENTS § 60-4.5 Hometown plans. (a) A contractor participating, either individually or through an association, in an approved Hometown Plan (including heavy...

  8. Effect of Leuconostoc mesenteroides 11 bacteriocin in the multiplication control of Listeria monocytogenes 4b Efeito da bacteriocina de Leuconostoc mesenteroides 11 no controle da multiplicação de Listeria monocytogenes 4b

    Directory of Open Access Journals (Sweden)

    Rafael C. R. Martinez

    2006-03-01

    Full Text Available The activity of a crude preparation of bacteriocin produced by the chicken meat isolate Leuconostoc mesenteroides 11, was evaluated at 8ºC and 15ºC against Listeria monocytogenes. The pathogen was inoculated in a crude preparation of the bacteriocin and its population was enumerated after 0.5 and 10 days. The title of the bacteriocin in the preparation was determined immediately before inoculation and after 10 days of incubation at both temperatures. As a negative control, a non-bacteriocin producing strain, Leuconostoc mesenteroides A13, was used. Bacteriocin of L. mesenteroides 11 partially inhibited L. monocytogenes at 8ºC, but at 15ºC it was unable to prevent growth of the pathogen. Our findings suggest that the use of the semi-purified bacteriocin of L. mesenteroides 11 probably will not be suitable as a single hurdle to prevent L. monocytogenes growth in foods.A atividade de uma preparação bruta de bacteriocina produzida por Leuconostoc mesenteroides 11, isolado de peito de frango, foi avaliada a 8ºC e 15ºC, contra Listeria monocytogenes. O patógeno foi inoculado em uma preparação bruta da bacteriocina e sua população foi enumerada depois de 0,5 e 10 dias de incubação. O título da preparação de bacteriocina foi determinado no tempo 0 e após 10 dias de incubação em ambas as temperaturas. Como controle negativo, foi utilizada uma cepa não produtora de bacteriocina, Leuconostoc mesenteroides A13. A bacteriocina de L. mesenteroides 11 inibiu parcialmente L. monocytogenes a 8ºC, mas a 15ºC a bacteriocina não foi capaz de impedir a multiplicação do patógeno. Nossos resultados sugerem que o uso da bacteriocina semi-purificada de L. mesenteroides 11 provavelmente não será adequada como único obstáculo para impedir a multiplicação de L. monocytogenes em alimentos.

  9. Survival characteristics and the applicability of predictive mathematical modelling to Listeria monocytogenes growth in sous vide products.

    Science.gov (United States)

    Nyati, H

    2000-06-01

    Survival and growth of Listeria monocytogenes isolates during sous vide processing and storage, and the applicability of predictive modelling in determining the potential for growth of L. monocytogenes in broth models and in sous vide products was investigated. L. monocytogenes grew in anaerobic tryptose phosphate broth and in chicken and beef samples by 2 log cycles in 8 days at 3 degrees C and 4-5 log cycles in 6 days at 8 degrees C. However, heating to an internal temperature of 70 degrees C resulted in a 4-5 log reduction and 70 degrees C/2 min resulted in a reduction greater than 7 log cycles. Lowering the product pH to 5.0 was effective in inhibiting L. monocytogenes growth, whereas a sodium chloride concentration of 2% had a negligible effect on growth rates. The square root model (Ratkowsky et al., 1983) predicted L. monocytogenes growth rates at 0-25 degrees C with a coefficient of determination (R2 value) of 98.36-99.63% and a bias factor of 1.08 to 1.21 in beef, chicken and broth substrates of unmodified pH. In addition, the Response Surface Polynomial Model (Version 3.1, Buchanan et al., 1989) predicted generation times at 5-25 degrees C with a 0-17.4% difference between observed and expected generation times in tryptose phosphate broth at pH 7.3. There were however, large differences (25.5 vs. 5.3 h) between observed generation times at pH 5.6 (8 degrees C) and those predicted by the Pathogen Modelling Program in tryptose phosphate broth. A divergence from predicted values was also noted at lower temperatures (0-3.5 degrees C) in the square root model.

  10. Predicting growth-no growth of Listeria monocytogenes on vacuum-packaged ready-to-eat meats.

    Science.gov (United States)

    Ingham, Steven C; Borneman, Darand L; Ané, Cécile; Ingham, Barbara H

    2010-04-01

    Compliance with U.S. Department of Agriculture (USDA) composition-based labeling standards often has been regarded as evidence of the shelf stability of ready-to-eat (RTE) meats. However, the USDA now requires further proof of shelf stability. Our previous work included development of equations for predicting the probability of Staphylococcus aureus growth based on the pH and a(w) of an RTE product. In the present study, we evaluated the growth-no-growth during 21 degrees C storage of Listeria monocytogenes on 39 vacuum-packaged commercial RTE meat products with a wide range of pH (4.6 to 6.5), a(w) (0.47 to 0.98), and percent water-phase salt (%WPS; 2.9 to 34.0). Pieces of each product were inoculated with a five-strain cocktail of L. monocytogenes and vacuum packaged, and L. monocytogenes levels were determined immediately after inoculation and after storage at 21 degrees C for up to 5 weeks. L. monocytogenes grew on 13 of 14 products labeled "keep refrigerated" but not on any of the 25 products sold as shelf stable. Using bias reduction logistic regression data analysis, the probability of L. monocytogenes growth (Pr) could be predicted as a function of pH and a(w): Pr = exp[-59.58 + (4.67 x pH) + (35.05 x a(w))]/{1 + exp[-59.58 + (4.67 x pH) + (35.05 x a(w))]}. Pr also could be predicted as a function of pH and %WPS: Pr = exp[-20.52 + (4.10 x pH) - (0.51 x %WPS)]/{1 + exp[-20.52 + (4.10 x pH) - (0.51 x %WPS)]}. The equations accurately predicted L. monocytogenes growth (Pr values of 0.68 to 0.99) or no growth (Pr values of <0.01 to 0.26) and with our equations for predicting S. aureus growth will be useful for evaluating RTE meat shelf stability.

  11. Survival and Growth of Listeria monocytogenes on Fresh-Cut "Athena" and "Rocky Ford" Cantaloupes During Storage at 4°C and 10°C.

    Science.gov (United States)

    Nyarko, Esmond; Kniel, Kalmia E; Reynnells, Russell; East, Cheryl; Handy, Eric T; Luo, Yaguang; Millner, Patricia D; Sharma, Manan

    2016-11-01

    Cantaloupes, marketed as "Rocky Ford," were implicated in the U.S. multistate outbreak of listeriosis in 2011, which caused multiple fatalities. Listeria monocytogenes can survive on whole cantaloupes and can be transferred to the flesh of melons. The growth of L. monocytogenes on fresh-cut "Athena" and "Rocky Ford" cantaloupe cultivars during refrigerated storage was evaluated. Fresh-cut cubes (16.4 cm(3)) from field-grown cantaloupes were each inoculated with 5 log10 CFU/mL of a multi-strain mixture of L. monocytogenes and stored at 4°C or 10°C. Inoculated fresh-cut cubes were also: (1) continuously stored at 4°C for 3 days; (2) temperature-abused (TA: 25°C for 4 h) on day 0; or (3) stored at 4°C for 24 h, exposed to TA on day 1, and subsequently stored at 4°C until day 3. L. monocytogenes populations on fresh-cut melons continuously stored at 4°C or 10°C were enumerated on selected days for up to 15 days and after each TA event. Brix values for each cantaloupe variety were determined. L. monocytogenes populations on fresh-cut cantaloupe cubes stored at 4°C increased by 1.0 and 3.0 log10 CFU/cube by day 7 and 15, respectively, whereas those stored at 10°C increased by 3.0 log10 CFU/cube by day 7. Populations of L. monocytogenes on fresh-cut cantaloupes stored at 10°C were significantly (p fresh-cut "Athena" and "Rocky Ford" cubes, even though "Athena" cubes had significantly higher Brix values than the "Rocky Ford" fruit. L. monocytogenes populations on fresh-cut cantaloupes exposed to TA on day 1 and then refrigerated were significantly greater (0.74 log10 CFU) than those stored continuously at 4°C for 3 days. Storage at 10°C or exposure to TA events promoted growth of L. monocytogenes on fresh-cut cantaloupe during refrigerated storage.

  12. Assessing the capacity of growth, survival, and acid adaptive response of Listeria monocytogenes during storage of various cheeses and subsequent simulated gastric digestion.

    Science.gov (United States)

    Kapetanakou, Anastasia E; Gkerekou, Maria A; Vitzilaiou, Eirini S; Skandamis, Panagiotis N

    2017-04-04

    Different physicochemical and microbiological characteristics of cheeses may affect Listeria monocytogenes potential to grow, survive, or exhibit an acid adaptive response during storage and digestion. The objectives of the present study were to assess: i) the survival or growth potential of L.monocytogenes on various cheeses during storage, ii) the effect of initial indigenous microbiota on pathogen growth in comparison to expected growth curves retrieved by existing predictive models, and iii) the impact of habituation on/in cheeses surfaces on the subsequent acid resistance during simulated gastric digestion. Portions of cream (Cottage and Mascarpone), soft (Anthotyros, Camembert, Mastelo®, Manouri, Mozzarella, Ricotta), and semi-hard (Edam, Halloumi, Gouda) cheeses were inoculated with ca. 100CFU/g or cm(2) of L.monocytogenes and stored under vacuum or aerobic conditions at 7°C (n=4). The impact of varying (initial) levels of starter culture or indigenous spoilage microbiota on pathogen growth was evaluated by purchasing cheese packages on different dates in relation to production and expiration date (subsequently reflecting to different batches) mimicking a potential situation of cheese contamination with L.monocytogenes during retail display. Values of pH and aw were also monitored and used to simulate growth of L. monocytogenes by existing models and compare it with the observed data of the study. Survival in simulated gastric fluid (SGF) (pH1.5; HCl; max. 120min) was assessed at three time points during storage. Mascarpone, Ricotta, Mozzarella, Camembert, and Halloumi supported L.monocytogenes growth by 0.5-0.8logCFU/g or cm(2)per day, since low initial levels of total viable counts (TVC) (1.8-3.8logCFU/g or cm(2)) and high pH/aw values (ca. 6.23-6.64/0.965-0.993) were recorded. On Cottage, Anthotyros, Manouri, Mastelo®, Edam, and Gouda, the pathogen survived at populations similar or lower than the inoculation level due to the high reported competition

  13. The effect of sodium reduction with and without potassium chloride on the survival of Listeria monocytogenes in Cheddar cheese.

    Science.gov (United States)

    Hystead, E; Diez-Gonzalez, F; Schoenfuss, T C

    2013-10-01

    Sodium chloride (NaCl) in cheese contributes to flavor and texture directly and by its effect on microbial and enzymatic activity. The salt-to-moisture ratio (S/M) is used to gauge if conditions for producing good-quality cheese have been met. Reductions in salt that deviate from the ideal S/M range could result in changing culture acidification profiles during cheese making. Lactococcus lactis ssp. lactis or Lc. lactis ssp. cremoris are both used as cultures in Cheddar cheese manufacture, but Lc. lactis ssp. lactis has a higher salt and pH tolerance than Lc. lactis ssp. cremoris. Both salt and pH are used to control growth and survival of Listeria monocytogenes and salts such as KCl are commonly used to replace the effects of NaCl in food when NaCl is reduced. The objectives of this project were to determine the effects of sodium reduction, KCl use, and the subspecies of Lc. lactis used on L. monocytogenes survival in stirred-curd Cheddar cheese. Cheese was manufactured with either Lc. lactis ssp. lactis or Lc. lactis ssp. cremoris. At the salting step, curd was divided and salted with a concentration targeted to produce a final cheese with 600 mg of sodium/100 g (control), 25% reduced sodium (450 mg of sodium/100 g; both with and without KCl), and low sodium (53% sodium reduction or 280 mg of sodium/100 g; both with and without KCl). Potassium chloride was added on a molar equivalent to the NaCl it replaced to maintain an equivalent S/M. Cheese was inoculated with a 5-strain cocktail of L. monocytogenes at different times during aging to simulate postprocessing contamination, and counts were monitored over 27 or 50 d, depending on incubation temperature (12 or 5 °C, respectively). In cheese inoculated with 4 log₁₀ cfu of L. monocytogenes/g 2 wk after manufacture, viable counts declined by more than 3 log₁₀ cfu/g in all treatments over 60 d. When inoculated with 5 log₁₀ cfu/g at 3mo of cheese age, L. monocytogenes counts in Cheddar cheese were also

  14. C4.5 programs for machine learning

    CERN Document Server

    Quinlan, J Ross

    1992-01-01

    Classifier systems play a major role in machine learning and knowledge-based systems, and Ross Quinlan's work on ID3 and C4.5 is widely acknowledged to have made some of the most significant contributions to their development. This book is a complete guide to the C4.5 system as implemented in C for the UNIX environment. It contains a comprehensive guide to the system's use , the source code (about 8,800 lines), and implementation notes. The source code and sample datasets are also available for download (see below). C4.5 starts with large sets of cases belonging to known classes. The cases,

  15. Control options for Listeria monocytogenes in seafoods

    DEFF Research Database (Denmark)

    Huss, Hans Henrik; Jørgensen, Lasse Vigel; Vogel, Birte Fonnesbech

    2000-01-01

    At least three outbreaks of listeriosis associated with seafood have been reported. Listeria monocytogenes is widely distributed in the general environment including fresh water, coastal water and live fish from these areas. Contamination or recontamination of seafood may also take place during...

  16. Listeria monocytogenes : nog steeds een probleem?

    NARCIS (Netherlands)

    Beumer, R.R.

    2011-01-01

    Listeria monocytogenes is net als vele andere bacteriële voedselpathogenen al tientallen jaren bekend. De meeste grondstoffen voor voedingsmiddelen komen uit de akker- en tuinbouw, de veehouderij en de visserij. Besmetting vindt daar plaats met micro-organismen afkomstig uit grond, fecaliën, water,

  17. Prevalence of Listeria monocytogenes in poultry meat

    Directory of Open Access Journals (Sweden)

    Mehmet ELMALI

    2015-01-01

    Full Text Available AbstractThe objectives of this study were i to isolate Listeria spp. and Listeria monocytogenes in broiler wing meat samples, ii to confirm the isolates by PCR, based on prs and hly A gene sequences, iii to determine the seasonal and monthly distribution of the isolates. A total of 120 broiler wing meat samples (60 packaged pieces wrapped using strech film in styrofoam plates and 60 unpackaged pieces bought from different markets in Hatay province were analysed. Listeria spp. was isolated from 57 (47.5% out of 120 samples. Fifty-four, out of 57 Listeria spp. isolates were identified as L. monocytogenes. L. monocytogenes was isolated from the samples collected during the spring, winter, summer, and autumn at the levels of 26.6%, 40%, 53.3%, 60%, respectively. In this study, the isolation rates were found to be the highest in autumn, while the isolation rates were found to be the lowest in spring. As a consequence, high prevalence of Listeria spp. and L. monocytogenes in poultry wing meat samples may pose a risk for human health. We consider that with obeying the rules of good hygiene practices (GHP, good manufacturing practices (GMP and HACCP can minimize the contamination with Listeria spp.

  18. Listeria monocytogenes : nog steeds een probleem?

    NARCIS (Netherlands)

    Beumer, R.R.

    2011-01-01

    Listeria monocytogenes is net als vele andere bacteriële voedselpathogenen al tientallen jaren bekend. De meeste grondstoffen voor voedingsmiddelen komen uit de akker- en tuinbouw, de veehouderij en de visserij. Besmetting vindt daar plaats met micro-organismen afkomstig uit grond, fecaliën, water,

  19. Effect of salt types and concentrations on the high-pressure inactivation of Listeria monocytogenes in ground chicken.

    Science.gov (United States)

    Balamurugan, S; Ahmed, Rafath; Chibeu, Andrew; Gao, Anli; Koutchma, Tatiana; Strange, Phil

    2016-02-01

    National and international health agencies have recommended a significant reduction in daily intake of sodium by reducing the amount of NaCl in foods, specifically processed meats. However, sodium reduction could increase the risk of survival and growth of spoilage and pathogenic microorganisms on these products. Therefore, alternate processing technologies to improve safety of sodium reduced foods are necessary. This study examined the effects of three different salt types and concentrations on high-pressure inactivation of Listeria monocytogenes in pre-blended ground chicken formulations. Ground chicken formulated with three salt types (NaCl, KCl, CaCl2), at three concentrations (0, 1.5, 2.5%) and inoculated with a four strain cocktail of L. monocytogenes (10(8) CFU g(-1)) were subjected to four pressure treatments (0, 100, 300, 600 MPa) and two durations (60, 180 s) in an experiment with factorial design. Surviving cells were enumerated by plating on Oxford agar and analysed by factorial ANOVA. Pressure treatments at 100 or 300 MPa did not significantly (P=0.19-050) reduce L. monocytogenes populations. Neither salt type nor concentration had a significant effect on L. monocytogenes populations at these pressure levels. At 600 MPa, salt types, concentrations and duration of pressure treatment all had a significant effect on L. monocytogenes populations. Formulations with increasing concentrations of NaCl or KCl showed significantly lower reduction in L. monocytogenes, while increase in CaCl2 concentration resulted in a significantly higher L. monocytogenes reduction. For instance, increase in NaCl concentration from 0 to 1.5 or 2.5% resulted in a log reduction of 6.16, 2.49 and 1.29, respectively, when exposed to 600 MPa for 60s. In the case of CaCl2, increase from 0 to 1.5 or 2.5% resulted in a log reduction of 6.16, 7.28 and 7.47, respectively. These results demonstrate that high-pressure processing is a viable process to improve microbial safety of sodium

  20. 4,5-Diphenyl-1-methylimidazole: An Undergraduate Laboratory Experiment.

    Science.gov (United States)

    Anastas, Paul T.; And Others

    1985-01-01

    Background information and procedures used are provided for the synthesis of 4,5-diphenyl-methylimidazole. This experiment on the chemistry of heterocycles is ideally suited for beginning undergraduate organic chemistry students. (JN)

  1. Profilin binding to sub-micellar concentrations of phosphatidylinositol (4,5) bisphosphate and phosphatidylinositol (3,4,5) trisphosphate

    DEFF Research Database (Denmark)

    Moens, Pierre D J; Bagatolli, Luis A

    2007-01-01

    its interaction with phosphatidylinositol 4,5-bisphosphate [PI(4,5)P(2)] and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P(3)] (P.J. Lu, W.R. Shieh, S.G. Rhee, H.L. Yin, C.S. Chen, Lipid products of phosphoinositide 3-kinase bind human profilin with high affinity, Biochemistry 35 (1996) 14027......-14034). To date, profilin's interaction with polyphosphoinositides (PPI) has only been studied in micelles or small vesicles. Profilin binds with high affinity to small clusters of PI(4,5)P(2) molecules. In this work, we investigated the interactions of profilin with sub-micellar concentrations of PI(4,5)P(2......) and PI(3,4,5)P(3). Fluorescence anisotropy was used to determine the relevant dissociation constants for binding of sub-micellar concentrations of fluorescently labeled PPI lipids to profilin and we show that these are significantly different from those determined for profilin interaction with micelles...

  2. VIDAS Listeria monocytogenes II (LMO2).

    Science.gov (United States)

    Johnson, Ronald; Mills, John

    2013-01-01

    This AOAC GovVal study compared the VIDAS Listeria monocytogenes II (LMO2) to the Health Products and Food Branch MFHPB-30 reference method for detection of L. monocytogenes in ready-to-eat (RTE) meats. The VIDAS LMO2 test is an automated enzyme-linked fluorescent immunoassay for the detection of L. monocytogenes in foods. The LMO2 test, following the enrichment procedure from the MFLP-33 method, also included use of the chromogenic media, chromID Ottaviani Agosti Agar (OAA) and chromID Lmono for confirmation of LMO2 presumptive results. In previous AOAC validation studies comparing the VIDAS LMO2 method to the U.S. Food and Drug Administration Bacteriological Analytical Manual and U.S. Department of Agriculture-Food Safety and Inspection Service reference methods, LMO2 was approved as AOAC Official Method 2004.02 for the detection of L. monocytogenes in dairy products, vegetables, seafood, raw meats and poultry, and processed meats and poultry. The GovVal comparative study included 20 replicate test portions, each at two contamination levels for each matrix, where fractionally positive results (5-15 positive results/20 replicate portions tested) were obtained by at least one method at one level. Five uncontaminated controls were included. Chi-square analysis of the comparative data in this study indicates no statistical differences between the VIDAS LMO2 and the MFHPB-30 standard methods at the 5% level of significance. Confirmation of presumptive LMO2 results with the chromogenic OAA and Lmono media was shown to be equivalent to the appropriate reference method agars. The data demonstrate that the VIDAS LMO2 method is an acceptable alternative method to the MFHPB-30 standard culture method for the detection of L. monocytogenes in RTE meats, including liver paté, hot dogs, raw fermented sausage, sliced deli turkey, and sliced deli ham.

  3. Inactivation of Escherichia coli, Listeria monocytogenes and Yersinia enterocolitica in fermented sausages during maturation/storage.

    Science.gov (United States)

    Lindqvist, Roland; Lindblad, Mats

    2009-01-31

    The purpose of this study was to evaluate maturation and storage conditions as a way to increase the safety of non-heat treated fermented sausages. The specific objectives were to investigate the effects of storage time and temperature on the levels of Escherichia coli, Listeria monocytogenes and Yersinia enterocolitica in fermented sausages and in broth, and to validate how well the broth experiments and some published models can predict inactivation in sausage. One strain each of E. coli, L. monocytogenes and Y. enterocolitica with induced acid tolerance was inoculated into sausage batters representing a typical Swedish recipe for cold-smoked sausages. The sausages were fermented at 27 degrees C for 39 or 48 h and then stored at different temperatures (8, 15, or 20-22 degrees C) for up to 44 days. The levels of the experimental strains, lactic acid bacteria, and pH, a(w), and lactic acid was measured during the maturation/storage period. Inactivation in BHI broths adjusted to pH 4.4 or 4.6, water activity of 0.93, and with 1, 1.3 or 2% lactic acid added was also studied. For all strains inactivation rates increased with temperature in both broths and sausages. At 8 degrees C the storage time required for a one-log reduction in sausage ranged from 21 days for E. coli, >16 days for L. monocytogenes, to 18 days for Y. enterocolitica. At temperatures of 20 degrees C or more, the storage time needed for a one log reduction was shorter: between 7 to 11 days for E. coli, 4 to 7 days for L. monocytogenes, and 1 to 4 days for Y. enterocolitica. A published model based on temperature only yielded a good prediction of E. coli inactivation in sausage. A linear model based on the rate estimated in broth yielded a fair prediction of L. monocytogenes inactivation. The performance of other inactivation models validated was unsatisfactory. Significant E. coli growth which occurred in batters without salt during initial phases of fermentation resulted in a subsequent increased

  4. The effect of micro-architectural structure of cabbage substratum and or background bacterial flora on the growth of Listeria monocytogenes.

    Science.gov (United States)

    Ongeng, Duncan; Ryckeboer, Jaak; Vermeulen, An; Devlieghere, Frank

    2007-11-01

    The effect of micro-architectural structure of cabbage (Brassica oleracea var. capitata L.) substratum and or background bacterial flora on the growth of Listeria monocytogenes as a function of incubation temperature was investigated. A cocktail mixture of Pseudomonas fluorescens, Pantoea agglomerans and Lactobacillus plantarum was constituted to a population density of approximately 5 log CFU/ml in order to pseudo-simulate background bacterial flora of fresh-cut cabbage. This mixture was co-inoculated with L. monocytogenes (approximately 3 log CFU/ml) on fresh-cut cabbage or in autoclaved cabbage juice followed by incubation at different temperatures (4-30 degrees C). Data on growth of L. monocytogenes were fitted to the primary growth model of Baranyi in order to generate the growth kinetic parameters of the pathogen. During storage, microbial ecology was dominated by P. fluorescens and L. plantarum at refrigeration and abuse temperature, respectively. At all temperatures investigated, lag duration (lambda, h), maximum specific growth rate (micro(max), h(-1)) and maximum population density (MPD, log CFU/ml) of L. monocytogenes were only affected by medium micro-architectural structure, except at 4 degrees C where it had no effect on the micro(max) of the pathogen. Comparison of observed values of micro(max) with those obtained from the Pathogen Modelling Program (PMP), showed that PMP overestimated the growth rate of L. monocytogenes on fresh-cut cabbage and in cabbage juice, respectively. Temperature dependency of micro(max) of L. monocytogenes, according to the models of Ratkowsky and Arrhenius, showed linearity for temperature range of 4-15 degrees C, discontinuities and linearity again for temperature range of 20-30 degrees C. The results of this experiment have shown that the constituted background bacterial flora had no effect on the growth of L. monocytogenes and that micro-architectural structure of the vegetable was the primary factor that limited the

  5. Extraction of Cesium from the Irradiated Nuclear Waste by 4(5),4'(5')-Bis[1-hydroxyalkylbenzo]-21-crown-7

    Institute of Scientific and Technical Information of China (English)

    Ying DU; Wen Jun CHEN; Sheng Ying QIN

    2004-01-01

    4(5),4'(5')-Bis[l-hydroxyalkylbenzo]-21-crown-7 (A-C) have been synthesized by two-step reactions from dibenzo-21-crown-7 (DB21C7). Extraction of cesium cation from nitric acid solutions by A-C has been investigated in nitromethane. Under the conditions of various concentration of HNO3 or NaNO3, the extractabilities of A and B were superior to that of DB21C7.

  6. Changes in rumen bacterial community composition following feeding of silage inoculated with a commercial silage inoculant

    Science.gov (United States)

    Some silage inoculants yield an increase in milk production without increasing fiber digestibility, possibly through altering the rumen microflora. We hypothesized that silage treated with a commercial inoculant (Lactobacillus plantarum, LP) would improve milk production and would alter rumen bacter...

  7. Inoculation of sugarcane with diazotrophic bacteria

    Directory of Open Access Journals (Sweden)

    Nivaldo Schultz

    2014-04-01

    Full Text Available The sugarcane industry, a strategic crop in Brazil, requires technological improvements in production efficiency to increase the crop energy balance. Among the various currently studied alternatives, inoculation with diazotrophic bacteria proved to be a technology with great potential. In this context, the efficiency of a mixture of bacterial inoculant was evaluated with regard to the agronomic performance and N nutrition of sugarcane. The experiment was carried out on an experimental field of Embrapa Agrobiologia, in Seropédica, Rio de Janeiro, using a randomized block, 2 × 3 factorial design (two varieties and three treatments with four replications, totaling 24 plots. The varieties RB867515 and RB72454 were tested in treatments consisting of: inoculation with diazotrophic bacteria, N-fertilized control with 120 kg ha-1 N and absolute control (no inoculation and no N fertilizer. The inoculum was composed of five strains of five diazotrophic species. The yield, dry matter accumulation, total N in the shoot dry matter and the contribution of N by biological fixation were evaluated, using the natural 15N abundance in non-inoculated sugarcane as reference. The bacterial inoculant increased the stalk yield of variety RB72454 similarly to fertilization with 120 kg ha-1 N in the harvests of plant-cane and first ratoon crops, however the contribution of biological N fixation was unchanged by inoculation, indicating that the benefits of the inoculant in sugarcane may have resulted from plant growth promotion.

  8. Efficacy of activated alginate-based nanocomposite films to control Listeria monocytogenes and spoilage flora in rainbow trout slice.

    Science.gov (United States)

    Alboofetileh, Mehdi; Rezaei, Masoud; Hosseini, Hedayat; Abdollahi, Mehdi

    2016-01-01

    Essential oils of clove, coriander, caraway, marjoram, cinnamon, and cumin were tested for their antilisterial activity by application of agar diffusion assay (experiment 1). Marjoram essential oil (MEO) showed the highest inhibitory effect, followed by clove and cinnamon. Subsequently, these essential oils were incorporated to alginate/clay nanocomposite films and antilisterial effectiveness of the films was studied in a model solid food system during 12 days at 10 °C (experiment 2). The results revealed that the films with MEO were more effective against Listeria monocytogenes in the model step. Finally, alginate-clay film incorporating 1 % MEO was applied to inoculated trout slices during refrigerated storage (4 °C) for 15 days (experiment 3). The control and the wrapped fish samples were analyzed periodically for microbiological (L. monocytogenes, total viable count, psychrotrophic count) and chemical (TVB-N) properties. The results demonstrated that alginate-clay films enriched with 1 % MEO significantly delayed the growth of L. monocytogenes during the 15-day storage with final counts reaching 6.23 log CFU/g while the counts in control samples were significantly higher reaching 7.38 log CFU/g (p < 0.05). Furthermore, active films efficiently reduced total viable count and psychrotrophic count as well as TVB-N in the fish slice during refrigerated storage.

  9. Shelf life extension of ricotta cheese using coatings of galactomannans from nonconventional sources incorporating nisin against Listeria monocytogenes.

    Science.gov (United States)

    Martins, Joana T; Cerqueira, Miguel A; Souza, Bartolomeu W S; Carmo Avides, Maria do; Vicente, António A

    2010-02-10

    Shelf life extension of Ricotta cheese was evaluated at 4 degrees C upon the use of edible coatings made of galactomannans from Gleditsia triacanthos incorporating nisin against Listeria monocytogenes. Three different treatments were tested in cheese: samples without coating; samples with coating without nisin; and samples with coating containing 50 IU x g(-1) of nisin. To test the effectiveness of the treatments against L. monocytogenes, the surface of the cheese was inoculated with a suspension of the microorganism. Microbiological and physical-chemical analyses of the cheese samples were performed during 28 days. Results showed that the cheese coated with nisin-added galactomannan film was the treatment presenting the best results in terms of microbial growth delay (p < 0.05). The addition of nisin also affects (p < 0.05) the physical and mechanical properties of the films: O(2) permeability decreased from 1.84 to 1.35 x 10(-12) cm(3) x (Pa x s x m)(-1); CO(2) permeability increased from 1.96 to 6.31 x 10(-12) cm(3).(Pa x s x m)(-1); opacity increased from 3.68 to 4.59%; tensile strength ranged from 0.84 to 1.46 MPa; and elongation at break improved from 50.93 to 68.16%. These results demonstrate that novel galactomannan-based edible coatings, when combined with nisin, may provide consumer-friendly alternatives to reduce L. monocytogenes postcontamination on cheese products during storage.

  10. Use of titanium dioxide (TiO2) photocatalysts as alternative means for Listeria monocytogenes biofilm disinfection in food processing.

    Science.gov (United States)

    Chorianopoulos, N G; Tsoukleris, D S; Panagou, E Z; Falaras, P; Nychas, G-J E

    2011-02-01

    The aim of this work was to study the photocatalytic activity of titanium dioxide (TiO(2)) against Listeria monocytogenes bacterial biofilm. Different TiO(2) nanostructured thin films were deposited on surfaces such as stainless steel and glass using the doctor-blade technique. All the surfaces were placed in test tubes containing Brain Heart (BH) broth and inoculated with L. monocytogenes. Test tubes were then incubated for 10 days at 16°C in order to allow biofilm development. After biofilm formation, the surfaces were illuminated by ultraviolet A light (UVA; wavelength of 315-400 nm). The quantification of biofilms was performed using the bead vortexing method, followed by agar plating and/or by conductance measurements (via the metabolic activity of biofilm cells). The presence of the TiO(2) nanoparticles resulted in a fastest log-reduction of bacterial biofilm compared to the control test. The biofilm of L. monocytogenes for the glass nanoparticle 1 (glass surface modified by 16% w/v TiO(2)) was found to have decreased by 3 log CFU/cm(2) after 90 min irradiation by UVA. The use of TiO(2) nanostructured photocatalysts as alternative means of disinfecting contaminated surfaces presents an intriguing case, which by further development may provide potent disinfecting solutions. Surface modification using nanostructured titania and UV irradiation is an innovative combination to enhance food safety and economizing time and money.

  11. Behaviour of Listeria monocytogenes during the manufacture and ripening of Manchego and Chihuahua Mexican cheeses.

    Science.gov (United States)

    Solano-López, C; Hernández-Sánchez, H

    2000-12-05

    The ability of Listeria monocytogenes to survive the Mexican Manchego and Chihuahua cheese-making processes and its persistence during the ripening stages of both cheeses was examined. Commercial pasteurized and homogenized whole milk was inoculated with Listeria monocytogenes (strain ATCC 19114) to a level between 2 x 10(6) and 9 x 10(6) CFU/ml. The milk was used to make Mexican Manchego and Chihuahua cheeses in a 25-l vat. Mexican Manchego cheese was ripened for 5 days and Chihuahua cheese for 6 weeks at 12 degrees C and 85% RH. Listeria present in the cheese was enumerated by diluting samples in sterile 0.1% peptone water and plating on Oxford agar. Duplicate samples were taken at each step of the manufacturing process. During the first week of ripening samples were taken daily from both cheeses. For Chihuahua cheese, samples were taken weekly after the first week of the ripening stage. During the manufacture of Mexican Manchego cheese, Listeria counts remained relatively constant at 10(6) CFU/ml, while with Chihuahua cheese there was a one log decrease in numbers (10(6) to 10(5) CFU/ml). After pressing both curds overnight, numbers of bacteria decreased in Mexican Manchego cheese to 8.2 x 10(5) but increased in Chihuahua cheese from 1.7 x 10(5) to 1.2 x 10(6) CFU/ml. During the ripening stage, counts of Listeria remained constant in both cheeses. However, since the Chihuahua cheese ripening stage is about 6 weeks, the number of bacteria decreased from 2 x 10(6) to 4 x 10(4) CFU/g. The results show that Listeria monocytogenes is able to survive the manufacture and ripening processes of both Mexican cheeses.

  12. Identifying ingredients that delay outgrowth of Listeria monocytogenes in natural, organic, and clean-label ready-to-eat meat and poultry products.

    Science.gov (United States)

    McDonnell, Lindsey M; Glass, Kathleen A; Sindelar, Jeffrey J

    2013-08-01

    The objective of this study was to identify ingredients that inhibit Listeria monocytogenes in natural, organic, or clean-label ready-to-eat meat and poultry products. Fourteen ingredients were screened in uncured (no-nitrate-or-nitrite-added), traditional-cured (156 ppm of purified sodium nitrite), cultured (alternative cured, natural nitrate source, and Staphylococcus carnosus), or preconverted (alternative cured, natural nitrite source) turkey slurries. Slurries were cooked, cooled, inoculated to yield 3 log CFU/ml L. monocytogenes, stored at 4°C, and tested weekly for 4 weeks. Three antimicrobial ingredients, 1.5 % vinegar-lemon-cherry powder blend, 2.5 % buffered vinegar, and 3.0 % cultured sugar-vinegar blend, were incorporated into alternative-cured ham and uncured roast beef and deli-style turkey breast. Controls included all three meat products without antimicrobial ingredients and a traditional-cured ham with 2.8 % sodium lactate-diacetate. Cooked, sliced products were inoculated with 3 log CFU/g L. monocytogenes, vacuum packed, and stored at 4 or 7°C, for up to 12 weeks. For control products without antimicrobial agents stored at 4°C, a 2-log L. monocytogenes increase was observed at 2 weeks for ham and turkey and at 4 weeks for roast beef. Growth (>1-log increase) in the sodium lactate-diacetate was delayed until week 6. Compared with the control, the addition of either vinegar-lemon-cherry powder blend or buffered vinegar delayed L. monocytogenes growth for an additional 2 weeks, while the addition of cultured sugar-vinegar blend delayed growth for an additional 4 weeks for both ham and turkey. The greatest L. monocytogenes delay was observed in roast beef containing any of the three antimicrobial ingredients, with no growth detected through 12 weeks at 4°C for all the treatments. As expected, L. monocytogenes grew substantially faster in products stored at 7°C than at 4°C. These data suggest that antimicrobial ingredients from a natural source

  13. Colovesical fistula presenting as Listeria monocytogenes bacteraemia.

    Science.gov (United States)

    Hobbs, Mark

    2015-03-31

    We present a case of colovesical fistula presenting with a clinical syndrome of urosepsis subsequently demonstrated to be due to Listeria monocytogenes bacteraemia. The patient had a history of previous rectal cancer with a low anterior resection and a covering ileostomy that had been reversed 6 months prior to this presentation. L. monocytogenes was also isolated among mixed enteric organisms on urine culture. There were no symptoms or signs of acute gastrointestinal listeriosis or meningoencephalitis. This unusual scenario prompted concern regarding the possibility of communication between bowel and bladder, which was subsequently confirmed with CT and a contrast enema. The patient recovered well with intravenous amoxicillin and to date has declined surgical management of his colovesical fistula. This case illustrates the importance of considering bowel pathology when enteric organisms such as Listeria are isolated from unusual sites.

  14. Adenovirus-based vaccine against Listeria monocytogenes

    DEFF Research Database (Denmark)

    Jensen, Søren; Steffensen, Maria Abildgaard; Jensen, Benjamin Anderschou Holbech

    2013-01-01

    The use of replication-deficient adenoviruses as vehicles for transfer of foreign genes offers many advantages in a vaccine setting, eliciting strong cellular immune responses involving both CD8(+) and CD4(+) T cells. Further improving the immunogenicity, tethering of the inserted target Ag to MHC...... class II-associated invariant chain (Ii) greatly enhances both the presentation of most target Ags, as well as overall protection against viral infection, such as lymphocytic choriomeningitis virus (LCMV). The present study extends this vaccination concept to include protection against intracellular...... bacteria, using Listeria monocytogenes as a model organism. Protection in C57BL/6 mice against recombinant L. monocytogenes expressing an immunodominant epitope of the LCMV glycoprotein (GP33) was greatly accelerated, augmented, and prolonged following vaccination with an adenoviral vaccine encoding GP...

  15. Impact of dilution ratios on Listeria monocytogenes growth during University of Vermont medium enrichment of deli meats.

    Science.gov (United States)

    Zhang, Lei; Yan, Zhinong; Ryser, Elliot T

    2007-11-01

    In the U.S. Department of Agriculture (USDA) method for Listeria detection, a 25-g composite food sample is enriched in 225 ml of University of Vermont medium (UVM), giving a detection limit of 0.04 CFU/g. However, in a recent large-scale four-state deli meat survey for L. monocytogenes, 125-g samples enriched in 1,125 ml of UVM were requested to increase the detection limit to 0.008 CFU/g. To circumvent problems associated with large volumes of UVM, the impact on L. monocytogenes growth of lower dilution ratios used for enrichment and most-probable-number (MPN) detection was compared with the results obtained using the conventional 1:10 dilution. In this study, 125-g samples of cured turkey, uncured turkey, ham, and roast beef were inoculated with a six-strain L. monocytogenes cocktail to contain approximately 1 x 10(3) CFU/g. This cocktail was then diluted 1:3, 1:5, or 1:10 in UVM, homogenized, enriched at 30 degrees C, and periodically plated on modified Oxford agar to determine generation times during 24 h of incubation. The same enrichment protocol was also assessed in a three-tube MPN assay using 125-g samples inoculated with L. monocytogenes to contain approximately 1 CFU/g. The effects of two homogenization methods, stomaching and pulsifying, on Listeria growth were compared using oven-roasted turkey breast diluted 1:3, 1:5, and 1:10 in UVM. Overall, the growth rates, generation times, and MPN values for each of the four selected deli meats were similar (P > 0.05) using UVM enrichment ratios of 1:3, 1:5, and 1:10, with no significant (P > 0.05) differences in L. monocytogenes growth rate or generation time between experiments using pulsifying and stomaching. These findings indicate that lower volumes of UVM can be used in the USDA procedure when examining deli meats without compromising Listeria recovery.

  16. 15 CFR 4.5 - Responsibility for responding to requests.

    Science.gov (United States)

    2010-01-01

    ... GOVERNMENT INFORMATION Freedom of Information Act § 4.5 Responsibility for responding to requests. (a) In... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Responsibility for responding to... records, or the component to which the Departmental Freedom of Information Officer assigns lead...

  17. Regulation of inositol 1,4,5-trisphosphate receptor expression

    NARCIS (Netherlands)

    Deelman, Leo Edwin

    1999-01-01

    This thesis describes the regulation of the inositol 1,4,5-triphosphate receptor (InsP3R). The mechanisms of InsP3R regulation were investigated after cloning of the promoters of the human and rat InsP3R-1 gene and visualization of subcellular distribution of InsP3R-3 by immunoelectron microscopy (c

  18. Heat resistance of Listeria monocytogenes in vacuum packaged pasteurized fish fillets.

    Science.gov (United States)

    Ben Embarek, P K; Huss, H H

    1993-11-01

    The heat resistance of two strains of Listeria monocytogenes in sous-vide cooked fillets of cod and salmon was investigated. Fish sticks of 5 g were inoculated, vacuum-packed and heated at different combinations of time and temperature (58-80 degrees C). Time-temperature combinations allowing survival and time-temperature combinations at which the bacteria were destroyed, were used to determine D- and z-values. D-values were in the range of what has been published for other food products. D60-values were between 1.95 and 4.48 min depending on the strain and the fish. Both strains were one-four-times more heat resistant in salmon than in cod, showing the importance of the heating menstruum. This difference may be due to the higher fat content in salmon as compared to cod. Z-values were calculated to be 5.65 and 6.4 degrees C, respectively, for the two strains. The suitability of methods for heat resistance experiments and the survival of L. monocytogenes in sous-vide cooked fish fillets are discussed.

  19. Effect of potassium lactate and a potassium lactate-sodium diacetate blend on Listeria monocytogenes growth in modified atmosphere packaged sliced ham.

    Science.gov (United States)

    Mellefont, L A; Ross, T

    2007-10-01

    Two commercially available organic acid salts, potassium lactate (PURASAL HiPure P) and a potassium lactate-sodium diacetate blend (PURASAL Opti. Form PD 4), were assessed as potential inhibitors of Listeria monocytogenes growth in modified atmosphere packaged (MAP) sliced ham in challenge studies. The influence of the initial inoculation level of L. monocytogenes (10(1) or 10(3) CFU g(-1)) and storage temperature (4 or 8 degrees C) was also examined. The addition of either organic acid salt to MAP sliced ham strongly inhibited the growth of L. monocytogenes during the normal shelf life of the product under ideal refrigeration conditions (4 degrees C) and even under abusive temperature conditions (i.e., 8 degrees C). During the challenge studies and in the absence of either organic acid salt, L. monocytogenes numbers increased by 1000-fold after 20 days at 8 degrees C and 10-fold after 42 days at 4 degrees C. Both organic acid salt treatments were found to be listeriostatic rather than listericidal. The addition of either organic acid salt to the MAP ham also reduced the growth of indigenous microflora, i.e., aerobic microflora and lactic acid bacteria. The influence of these compounds on the risk of listeriosis in relation to product shelf life is discussed.

  20. Efficacy of freezing, frozen storage and edible antimicrobial coatings used in combination for control of Listeria monocytogenes on roasted turkey stored at chiller temperatures.

    Science.gov (United States)

    Jiang, Zheng; Neetoo, Hudaa; Chen, Haiqiang

    2011-10-01

    The presence and growth of Listeria monocytogenes on ready-to-eat (RTE) turkey is an important food safety issue. The antilisterial efficacy of four polysaccharide-based edible coatings (starch, chitosan, alginate and pectin) incorporating sodium lactate (SL) and sodium diacetate (SD) as well as commercial preparations Opti.Form PD4, NovaGARD™ CB1, Protect-M and Guardian™ NR100 were compared against L. monocytogenes on roasted turkey. Pectin coating treatments incorporating SL/SD, Opti.Form PD4 with or without Protect-M, and NovaGARD™ CB1 displayed higher antimicrobial efficacy against. L. monocytogenes than the other antimicrobials and coating materials. In the second phase of the study, it was investigated whether frozen storage could enhance the antilisterial effectiveness of pectin coating treatments on chilled roasted turkey. Inoculated roasted turkey samples coated with pectin-based treatments were frozen for up to 4 weeks and subsequently stored at 4 °C for 8 weeks. Frozen storage significantly enhanced the antilisterial activity of various coating treatments; with selected treatments reducing the L. monocytogenes populations by as much as 1.1 log CFU/cm(2) during the subsequent 8-week chilled storage. This study demonstrates that pectin-based antimicrobial edible coatings hold promise in enhancing the safety of RTE poultry products and frozen storage has the potential to enhance their effectiveness.

  1. Comparison of probabilistic and deterministic predictions of time to growth of Listeria monocytogenes as affected by pH and temperature in food.

    Science.gov (United States)

    Guevara, Leymaya; Martínez, Antonio; Fernández, Pablo S; Muñoz-Cuevas, Marina

    2011-01-01

    Stochastic models are useful for estimating the risk of foodborne illness and they can be integrated, besides other sources of variability, into microbial risk assessment. A stochastic approach to evaluate growth of two strains of Listeria monocytogenes influenced by different factors affecting microbial growth (pH and storage temperature) was performed. An individual-based approach of growth through optical density measurements was used. From results obtained, histograms of the lag phase were generated and distributions were fitted. Histograms presented increased variation when the factors applied were suboptimal for L. monocytogenes and they were combined. The extreme value distribution was ranked as the best one in most cases, whereas normal was the poorest fitting distribution. To evaluate the influence of pH and storage temperature on L. monocytogenes CECT 5672 in real food, commercial samples of courgette and carrot soup were inoculated with this pathogen. It was able to grow in both soups at storage temperatures from 4°C to 20°C. Using the distributions adjusted, predictions of time to growth (10² cfu/g) of L. monocytogenes were established by Monte Carlo simulation and they were compared with deterministic predictions and observations in foods.

  2. Inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in orange and tomato juice using ohmic heating.

    Science.gov (United States)

    Sagong, Hun-Gu; Park, Sang-Hyun; Choi, Young-Jin; Ryu, Sangryeol; Kang, Dong-Hyun

    2011-06-01

    The effects of ohmic heating on reduction of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in orange and tomato juice were investigated. Orange and tomato juice inoculated with E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes were subjected to ohmic heating with selected parameters including electric field strength from 10 to 20 V/cm and treatment times from 0 to 540 s. The number of pathogens was reduced by increasing the electric field strength from 10 to 20 V/cm as well as increasing treatment time. The population of E. coli O157:H7 was reduced more than 5 log after 120, 210, and 540 s of treatment in orange juice with 20, 15, and 10 V/cm electric field strengths, respectively. In tomato juice, levels of E. coli O157:H7 were reduced more than 5 log after 90, 180, and 480 s with the same electric field strengths. Similar phenomena were observed for Salmonella Typhimurium and L. monocytogenes, but E. coli O157:H7 was the most resistant to ohmic heating treatment. These results show that ohmic heating is potentially useful for inactivation of E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes and that the effect of inactivation depends on applied electric field strength, treatment time, pathogen species, and type of juice.

  3. Radioresistance of Salmonella species and Listeria monocytogenes on minimally processed arugula (Eruca sativa Mill.): effect of irradiation on flavonoid content and acceptability of irradiated produce.

    Science.gov (United States)

    Nunes, Tatiana P; Martins, Cecília G; Behrens, Jorge H; Souza, Kátia L O; Genovese, Maria Inés; Destro, Maria Teresa; Landgraf, Mariza

    2008-02-27

    This work studied the radiation resistance of Listeria monocytogenes and Salmonella species and the effect of irradiation on leaf flavonoid content and sensory acceptability of minimally processed arugula. Immersion in ozone-treated water reduced the analyzed microorganisms by 1 log. L. monocytogenes and Salmonella were not isolated from samples. Samples of this vegetable were inoculated with a cocktail of Salmonella spp. and L. monocytogenes and exposed to gamma irradiation. D10 values for Salmonella ranged from 0.16 to 0.19 kGy and for L. monocytogenes from 0.37 to 0.48 kGy. Kaempferol glycoside levels were 4 and ca. 3 times higher in samples exposed to 1 and 2 kGy, respectively, than in control samples. An increase in quercetin glycoside was also observed mainly in samples exposed to 1 kGy. In sensory evaluation, arugula had good acceptability, even after exposure to 2 and 4 kGy. These results indicate that irradiation has potential as a practical processing step to improve the safety of arugula.

  4. Evaluation of aqueous and alcohol-based quaternary ammonium sanitizers for inactivating Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes on peanut and pistachio shells.

    Science.gov (United States)

    McEgan, Rachel; Danyluk, Michelle D

    2015-05-01

    This study evaluated the efficacy of aqueous (aQUAT) and isopropyl alcohol-based quaternary ammonium (ipQUAT) sanitizers for reducing Salmonella spp., Escherichia coli O157:H7, or Listeria monocytogenes populations on peanut and pistachio shell pieces. Inoculated nutshells were mixed with QUAT sanitizers, water, or 70% ethanol and enumerated immediately or after incubation at 30 °C for 48 h. None of the treatments had any immediate effect on Salmonella or E. coli O157:H7 populations on the peanut or pistachio shells. L. monocytogenes populations declined immediately on the peanut and pistachio shells treated with aQUAT or ipQUAT. After incubation, Salmonella and E. coli O157:H7 populations increased significantly on the water- or aQUAT-treated peanut and pistachio shells. L. monocytogenes populations also increased significantly on the water- or aQUAT-treated peanut shells, but levels did not change on the water-treated pistachio shells and levels were just above the limit of detection on the aQUAT-treated pistachio shells. After treatment with ipQUAT and 48-h incubation, Salmonella and E. coli O157:H7 populations decreased to or below the limit of detection on both shell types; L. monocytogenes populations remained at or below the limit of detection on both shell types.

  5. [Evaluation of the effect of probiotic cultures added to commercial yogurt over a known population of Listeria monocytogenes and Escherichia coli O157:H7].

    Science.gov (United States)

    Barrantes, Xinia; Railey, Dylana; Arias, María Laura; Chaves, Carolina

    2004-09-01

    The effect of probiotic cultures over Listeria monocytogenes and Escherichia coli O157:H7 during yogurt storage was evaluated. Two different yogurt brands, one with additional probiotic cultures (Lactobacillus casei and L. acidophilus) were inoculated with known populations (106 UFC/g) of either L. monocytogenes or E. coli O157:H7 in three different times and stored for 32 days at 5 degrees C. Every four days the count of lactic bacteria, the added pathogens and pH was evaluated, according to the methodology described in the Bacteriological Analytical Manual. The pH and lactic bacteria population were constant during the testing period. Yogurt with additional probiotic cultures reduced the population of L. monocytogenes in 8 days, the population of E. coli O157:H7 in 16; yogurt with no additional probiotics took 20 days to reduce L. monocytogenes to non-detectable levels and even after 28 days of storage, E. coli O157:H7 was cultured. In this work, the beneficial effects of additional probiotic cultures in yogurt is confirmed again.

  6. Recombinant phage probes for Listeria monocytogenes

    Energy Technology Data Exchange (ETDEWEB)

    Carnazza, S; Gioffre, G; Felici, F; Guglielmino, S [Department of Microbiological, Genetic and Molecular Sciences, University of Messina, Messina (Italy)

    2007-10-03

    Monitoring of food and environmental samples for biological threats, such as Listeria monocytogenes, requires probes that specifically bind biological agents and ensure their immediate and efficient detection. There is a need for robust and inexpensive affinity probes as an alternative to antibodies. These probes may be recruited from random peptide libraries displayed on filamentous phage. In this study, we selected from two phage peptide libraries phage clones displaying peptides capable of specific and strong binding to the L. monocytogenes cell surface. The ability of isolated phage clones to interact specifically with L. monocytogenes was demonstrated using enzyme-linked immunosorbent assay (ELISA) and confirmed by co-precipitation assay. We also assessed the sensitivity of phage-bacteria binding by PCR on phage-captured Listeria cells, which could be detected at a concentration of 10{sup 4} cells ml{sup -1}. In addition, as proof-of-concept, we tested the possibility of immobilizing the affinity-selected phages to a putative biosensor surface. The quality of phage deposition was monitored by ELISA and fluorescent microscopy. Phage-bacterial binding was confirmed by high power optical phase contrast microscopy. Overall, the results of this work validate the concept of affinity-selected recombinant filamentous phages as probes for detecting and monitoring bacterial agents under any conditions that warrant their recognition, including in food products.

  7. Recombinant phage probes for Listeria monocytogenes

    Science.gov (United States)

    Carnazza, S.; Gioffrè, G.; Felici, F.; Guglielmino, S.

    2007-10-01

    Monitoring of food and environmental samples for biological threats, such as Listeria monocytogenes, requires probes that specifically bind biological agents and ensure their immediate and efficient detection. There is a need for robust and inexpensive affinity probes as an alternative to antibodies. These probes may be recruited from random peptide libraries displayed on filamentous phage. In this study, we selected from two phage peptide libraries phage clones displaying peptides capable of specific and strong binding to the L. monocytogenes cell surface. The ability of isolated phage clones to interact specifically with L. monocytogenes was demonstrated using enzyme-linked immunosorbent assay (ELISA) and confirmed by co-precipitation assay. We also assessed the sensitivity of phage-bacteria binding by PCR on phage-captured Listeria cells, which could be detected at a concentration of 104 cells ml-1. In addition, as proof-of-concept, we tested the possibility of immobilizing the affinity-selected phages to a putative biosensor surface. The quality of phage deposition was monitored by ELISA and fluorescent microscopy. Phage-bacterial binding was confirmed by high power optical phase contrast microscopy. Overall, the results of this work validate the concept of affinity-selected recombinant filamentous phages as probes for detecting and monitoring bacterial agents under any conditions that warrant their recognition, including in food products.

  8. Heat treatment effects on tensile properties of V-(4-5) wt.% Cr-(4-5) wt.% Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)

    1997-08-01

    Effects of thermomechanical treatments on microstructures and mechanical properties are of interest for long term application of V-Cr-Ti alloys in fusion reactor systems. Influence of thermal annealing at 1050{degrees}C on stress/strain behavior, maximum engineering strength, and uniform and total elongation were evaluated. The results show that multiple annealing has minimal effect on the tensile properties of V-(4-5)Cr-(4-5)Ti alloys tested at room temperature and at 500{degrees}C.

  9. Inhibition of Listeria monocytogenes in Fresh Cheese Using Chitosan-Grafted Lactic Acid Packaging.

    Science.gov (United States)

    Sandoval, Laura N; López, Monserrat; Montes-Díaz, Elizabeth; Espadín, Andres; Tecante, Alberto; Gimeno, Miquel; Shirai, Keiko

    2016-01-01

    A chitosan from biologically obtained chitin was successfully grafted with d,l-lactic acid (LA) in aqueous media using p-toluenesulfonic acid as catalyst to obtain a non-toxic, biodegradable packaging material that was characterized using scanning electron microscopy, water vapor permeability, and relative humidity (RH) losses. Additionally, the grafting in chitosan with LA produced films with improved mechanical properties. This material successfully extended the shelf life of fresh cheese and inhibited the growth of Listeria monocytogenes during 14 days at 4 °C and 22% RH, whereby inoculated samples with chitosan-g-LA packaging presented full bacterial inhibition. The results were compared to control samples and commercial low-density polyethylene packaging.

  10. Inhibition of Listeria monocytogenes in Fresh Cheese Using Chitosan-Grafted Lactic Acid Packaging

    Directory of Open Access Journals (Sweden)

    Laura N. Sandoval

    2016-04-01

    Full Text Available A chitosan from biologically obtained chitin was successfully grafted with d,l-lactic acid (LA in aqueous media using p-toluenesulfonic acid as catalyst to obtain a non-toxic, biodegradable packaging material that was characterized using scanning electron microscopy, water vapor permeability, and relative humidity (RH losses. Additionally, the grafting in chitosan with LA produced films with improved mechanical properties. This material successfully extended the shelf life of fresh cheese and inhibited the growth of Listeria monocytogenes during 14 days at 4 °C and 22% RH, whereby inoculated samples with chitosan-g-LA packaging presented full bacterial inhibition. The results were compared to control samples and commercial low-density polyethylene packaging.

  11. Surgical cytoreduction restores the antitumor efficacy of a Listeria monocytogenes vaccine in malignant pleural mesothelioma.

    Science.gov (United States)

    Kennedy, Gregory T; Judy, Brendan F; Bhojnagarwala, Pratik; Moon, Edmund K; Fridlender, Zvi G; Albelda, Steven M; Singhal, Sunil

    2015-07-01

    Recent studies suggest that immunotherapy may offer a promising treatment strategy for early-stage malignant pleural mesothelioma (MPM), but advanced tumor burden may limit the efficacy of immunotherapy. Therefore, we hypothesized that surgical cytoreduction could restore the efficacy of vaccine-based immunotherapy for MPM. We developed a murine model of MPM through transduction of a mesothelioma cell line with mesothelin. We used this model to evaluate the efficacy of a Listeria monocytogenes vaccine expressing mesothelin. Tumor growth was significantly inhibited at four weeks in animals vaccinated two weeks prior to tumor cell inoculation as compared to those given an empty vector control (1371 ± 420 mm(3) versus 405 ± 139 mm(3); p surgery reduced MDSCs to levels comparable to those in tumor-naïve mice. This study demonstrates that cytoreduction surgery restores the efficacy of cancer vaccines for MPM by reducing tumor-related immunosuppression that impairs immunotherapy.

  12. Systemic and Local CC Chemokines Production in a Murine Model of Listeria monocytogenes Infection

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Repeated intragastric inoculation of Listeria monocytogenes into BALB/c mice resulted in prolonged bacteraemia and severe hepatic infection. Bacteria could also be isolated from the brain tissue of all experimental mice. During the inflammatory process, chemokine concentrations typically increased at the local site in comparison to the systemic level. The liver-to-serum ratio was more pronounced in the case of macrophage inflammatory protein 1 α (MIP-1 α , suggesting its role in the inflammatory response in the liver. The ratio of brain-to-serum concentration of monocyte chemoattractant protein 1 (MCP-1 remained the same as in the control animals, while it was lower in the infected mice, both in the case MIP-1 α and in the case of regulated on activation, normal T cell expressed and secreted (RANTES. This is in correlation with slight inflammatory infiltrates found in the brain tissue early in infection.

  13. Behaviour of Listeria monocytogenes and Escherichia coli O157:H7 during the cheese making of traditional raw-milk cheeses from Italian Alps

    Directory of Open Access Journals (Sweden)

    Elena Cosciani-Cunico

    2015-09-01

    Full Text Available The behaviour of Listeria monocytogenes and Escherichia coli O157:H7 was studied during the manufacture and ripening of two traditional Italian Alps cheeses. Each cheese type was manufactured in a pilot plan from raw cow milk (without the addition of starter cultures artificially inoculated with L. monocytogenes and E. coli O157:H7 to a final concentration of about 4 log CFU/mL. The pathogens were enumerated throughout the cheese making and ripening processes to study their behaviour. When the milk was inoculated with 4 Log CFU/mL, the pathogens counts increased in the first time during the manufacturing process and then remained constant, until the end of ripening, or decreased significantly. Results indicate that the environment and nature of food borne pathogens affected the concentration of the bacteria during the manufacturing and ripening process. Thus, the presence of low cells numbers of L. monocytogenes and E. coli O157:H7 in milk destined for the production of raw milk cheeses characterized by a cooking of the curd less than 48°C can constitute a hazard for the consumer.

  14. Effectiveness of electrolyzed acidic water in killing Escherichia coli O157:H7, Salmonella enteritidis, and Listeria monocytogenes on the surfaces of tomatoes.

    Science.gov (United States)

    Bari, M L; Sabina, Y; Isobe, S; Uemura, T; Isshiki, K

    2003-04-01

    A study was conducted to evaluate the efficacy of electrolyzed acidic water, 200-ppm chlorine water, and sterile distilled water in killing Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on the surfaces of spot-inoculated tomatoes. Inoculated tomatoes were sprayed with electrolyzed acidic water, 200-ppm chlorine water, and sterile distilled water (control) and rubbed by hand for 40 s. Populations of E. coli O157:H7, Salmonella, and L. monocytogenes in the rinse water and in the peptone wash solution were determined. Treatment with 200-ppm chlorine water and electrolyzed acidic water resulted in 4.87- and 7.85-log10 reductions, respectively, in Escherichia coli O157:H7 counts and 4.69- and 7.46-log10 reductions, respectively, in Salmonella counts. Treatment with 200-ppm chlorine water and electrolyzed acidic water reduced the number of L. monocytogenes by 4.76 and 7.54 log10 CFU per tomato, respectively. This study's findings suggest that electrolyzed acidic water could be useful in controlling pathogenic microorganisms on fresh produce.

  15. Inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in ready-to-bake cookie dough by gamma and electron beam irradiation.

    Science.gov (United States)

    Jeong, Seul-Gi; Kang, Dong-Hyun

    2017-06-01

    This study was conducted to investigate the efficacy of gamma and electron beam irradiation to inactivate foodborne pathogens in ready-to-bake cookie dough and to determine the effect on quality by measuring color and texture changes. Cookie dough inoculated with Escherichia coli O157:H7, Salmonella Typhimurium, or Listeria monocytogenes was subjected to gamma and electron beam irradiation, with doses ranging from 0 to 3 kGy. As the radiation dose increased, the inactivation effect increased among all tested pathogens. After 3.0 kGy of gamma and electron beam irradiation, numbers of inoculated pathogens were reduced to below the detection limit (1 log CFU/g). The D10-values of E. coli O157:H7, S. Typhimurium, and L. monocytogenes in cookie dough treated with gamma rays were 0.53, 0.51, and 0.71 kGy, respectively, which were similar to those treated by electron beam with the same dose. Based on the D10-value of pathogens in cookie dough, L. monocytogenes showed more resistance to both treatments than did E. coli O157:H7 and S. Typhimurium. Color values and textural characteristics of irradiated cookie dough were not significantly (P > 0.05) different from the control. These results suggest that irradiation can be applied to control pathogens in ready-to-bake cookie dough products without affecting quality.

  16. Radiation processing to ensure safety of minimally processed carrot (Daucus carota) and cucumber (Cucumis sativus): optimization of dose for the elimination of Salmonella Typhimurium and Listeria monocytogenes.

    Science.gov (United States)

    Dhokane, V S; Hajare, S; Shashidhar, R; Sharma, A; Bandekar, J R

    2006-02-01

    Minimally processed vegetables are in demand, because they offer convenience to consumers. However, these products are often unsafe because of possible contamination with pathogens, such as Salmonella, Escherichia coli O157:H7, and Shigella species. Therefore, this study was carried out to optimize the radiation dose necessary to ensure the safety of precut carrot and cucumber. Decimal reduction doses (D-values) of Salmonella Typhimurium MTCC 98 were ca. 0.164 kGy in carrot samples and 0.178 kGy in cucumber samples. D-values of Listeria monocytogenes were determined to be 0.312 and 0.345 kGy in carrot and cucumber samples, respectively. Studies of inoculated, packaged, minimally processed carrot and cucumber samples showed that treatment with a 1-kGy dose of gamma radiation eliminated up to 4 log CFU/g of Salmonella Typhimurium and 3 log CFU/g of L. monocytogenes. However, treatment with a 2-kGy dose was necessary to eliminate these pathogens by 5 log CFU/g. Storage studies showed that both Salmonella Typhimurium and L. monocytogenes were able to grow at 10 degrees C in inoculated control samples. Neither of these pathogens could be recovered from radiation-processed samples after storage for up to 8 days.

  17. High hydrostatic pressure and biopreservation of dry-cured ham to meet the Food Safety Objectives for Listeria monocytogenes.

    Science.gov (United States)

    Hereu, Anna; Bover-Cid, Sara; Garriga, Margarita; Aymerich, Teresa

    2012-03-15

    This work aimed to evaluate the effect of nisin application (biopreservation) combined with high hydrostatic pressure processing (HHP) on the behavior of Listeria monocytogenes CTC1034 intentionally inoculated (at ca. 10(7)cells/g) onto the surface of ready-to-eat (RTE) sliced dry-cured ham. Two types of dry-cured ham, which had different water activities and fat contents were studied (a(w) of 0.92 and 14.25% fat and a(w) of 0.88 and 33.26% fat). Three batches were prepared for each type of product: (C) control, without nisin; (N) nisin directly applied (200 AU/cm(2)) and (F) nisin applied through active packaging, polyvinyl alcohol films with 200 AU/cm(2). Half of the samples were pressurized at 600 MPa for 5min. Counts of L. monocytogenes were periodically monitored throughout 60 days of storage at 8°C. The physico-chemical characteristics of the products enabled the survival of L. monocytogenes, but it was significantly reduced by the presence of nisin. The effect of biopreservation was greater when applied directly to the surface and in the product with lower water activity in comparison with the active packaging and the high water activity products, respectively. The immediate inactivation of L. monocytogenes by HHP ranged from 1.82 to 3.85 Log units, depending on the type of dry-cured ham. The lower the water activity, the less was the inactivation induced by HHP, both immediately and during storage. The reduction of L. monocytogenes immediately after HHP and during storage was more evident in batches with nisin applied directly to the surface of the product. The pathogen was not detected in some samples from day 5 of storage in the product with higher water activity. The effect of nisin applied through active packaging was lower than the direct application. The results of the present study indicated that HHP, as post-processing listericidal treatment, is more effective (both immediately and long term) than the use of nisin as an antimicrobial measure

  18. Highly specific fiber optic immunosensor coupled with immunomagnetic separation for detection of low levels of Listeria monocytogenes and L. ivanovii

    Directory of Open Access Journals (Sweden)

    Mendonça Marcelo

    2012-11-01

    Full Text Available Abstract Background Immunomagnetic separation (IMS and immunoassays are widely used for pathogen detection. However, novel technology platforms with highly selective antibodies are essential to improve detection sensitivity, specificity and performance. In this study, monoclonal antibodies (MAbs against Internalin A (InlA and p30 were generated and used on paramagnetic beads of varying diameters for concentration, as well as on fiber-optic sensor for detection. Results Anti-InlA MAb-2D12 (IgG2a subclass was specific for Listeria monocytogenes and L. ivanovii, and p30-specific MAb-3F8 (IgM was specific for the genus Listeria. At all bacterial concentrations (103–108 CFU/mL tested in the IMS assay; the 1-μm diameter MyOne beads had significantly higher capture efficiency (P 5 CFU/mL was significantly higher (P Listeria antibody (9 %. Furthermore, capture efficiency for MyOne-2D12 was highly specific for L. monocytogenes and L. ivanovii. Subsequently, we captured L. monocytogenes by MyOne-2D12 and MyOne-3F8 from hotdogs inoculated with mono- or co-cultures of L. monocytogenes and L. innocua (10–40 CFU/g, enriched for 18 h and detected by fiber-optic sensor and confirmed by plating, light-scattering, and qPCR assays. The detection limit for L. monocytogenes and L. ivanovii by the fiber-optic immunosensor was 3 × 102 CFU/mL using MAb-2D12 as capture and reporter antibody. Selective media plating, light-scattering, and qPCR assays confirmed the IMS and fiber-optic results. Conclusions IMS coupled with a fiber-optic sensor using anti-InlA MAb is highly specific for L. monocytogenes and L. ivanovii and enabled detection of these pathogens at low levels from buffer or food.

  19. Acute Fetal Demise with First Trimester Maternal Infection Resulting from Listeria monocytogenes in a Nonhuman Primate Model

    Science.gov (United States)

    Wolfe, Bryce; Wiepz, Gregory J.; Schotzko, Michele; Bondarenko, Gennadiy I.; Durning, Maureen; Simmons, Heather A.; Mejia, Andres; Faith, Nancy G.; Sampene, Emmanuel; Suresh, Marulasiddappa; Kathariou, Sophia; Czuprynski, Charles J.

    2017-01-01

    ABSTRACT Infection with Listeria monocytogenes during pregnancy is associated with miscarriage, preterm birth, and neonatal complications, including sepsis and meningitis. While the risk of these conditions is thought to be greatest during the third trimester of pregnancy, the determinants of fetoplacental susceptibility to infection, the contribution of gestational age, and the in vivo progression of disease at the maternal-fetal interface are poorly understood. We developed a nonhuman primate model of listeriosis to better understand antecedents of adverse pregnancy outcomes in early pregnancy. Four pregnant cynomolgus macaques (Macaca fascicularis) received a single intragastric inoculation between days 36 and 46 of gestation with 107 CFU of an L. monocytogenes strain isolated from a previous cluster of human listeriosis cases that resulted in adverse pregnancy outcomes. Fecal shedding, maternal bacteremia, and fetal demise were consistently noted within 7 to 13 days. Biopsy specimens of maternal liver, spleen, and lymph node displayed variable inflammation and relatively low bacterial burden. In comparison, we observed greater bacterial burden in the decidua and placenta and the highest burden in fetal tissues. Histopathology indicated vasculitis, fibrinoid necrosis, and thrombosis of the decidual spiral arteries, acute chorioamnionitis and villitis in the placenta, and hematogenous infection of the fetus. Vascular pathology suggests early impact of L. monocytogenes infection on spiral arteries in the decidua, which we hypothesize precipitates subsequent placentitis and fetal demise. These results demonstrate that L. monocytogenes tropism for the maternal reproductive tract results in infection of the decidua, placenta, and the fetus itself during the first trimester of pregnancy. PMID:28223455

  20. The overgrowth of Listeria monocytogenes by other Listeria spp. in food samples undergoing enrichment cultivation has a nutritional basis.

    Science.gov (United States)

    Besse, Nathalie Gnanou; Barre, Lena; Buhariwalla, Colin; Vignaud, Marie Léone; Khamissi, Elissa; Decourseulles, Emilie; Nirsimloo, Marjorie; Chelly, Minyar; Kalmokoff, Martin

    2010-01-01

    The isolation of Listeria monocytogenes from food is carried out using a double enrichment. In cases where multiple Listeria species are present within the original sample, L. monocytogenes can be overgrown during enrichment by other species of listeria present in the original sample. From a practical perspective, this can result in a false negative or complicate the ability of public health investigators to match food and clinical isolates. We have further investigated this phenomenon by analysing the growth kinetics of single species and pairs of different species over the ISO 11290-1 enrichment process. The overgrowth of a strain of L. monocytogenes by a strain of Listeria innocua resulted primarily from interactions which occurred in late exponential phase, where it was observed that growth of both strains stopped when the dominant strain reached stationary phase. In a second mixed culture, the dominant L. monocytogenes strain suppressed the exponential growth rate of the second Listeria welshimeri strain. Both findings suggest that the overgrowth could partially be explained in terms of a nutritional competition. Multi-factor analysis of Fraser broth constituents and growth temperatures using both stressed and non-stressed inoculants failed to identify any single factor in the ISO 11290-1 methodology which would contribute to the overgrowth phenomenon in our model system. Furthermore, species was not a significant factor in observed differences in growth parameters among a wider array of strains which had been stressed or not stressed prior to grown in Fraser broths, even though some strains had significantly faster growth rates than others. Limiting diffusion in Fraser broth through the addition of agar significantly reduced the extent of the overgrowth in experiments using mixtures of strains originally isolated from foods where overgrowth had been previously observed. Taken together, these findings support that the overgrowth phenomenon in most instances

  1. Predictive modeling for growth of non- and cold-adapted Listeria monocytogenes on fresh-cut cantaloupe at different storage temperatures.

    Science.gov (United States)

    Hong, Yoon-Ki; Yoon, Won Byong; Huang, Lihan; Yuk, Hyun-Gyun

    2014-06-01

    The aim of this study was to determine the growth kinetics of Listeria monocytogenes, with and without cold-adaption, on fresh-cut cantaloupe under different storage temperatures. Fresh-cut samples, spot inoculated with a 4-strain cocktail of L. monocytogenes (∼3.2 log CFU/g), were exposed to constant storage temperatures held at 10, 15, 20, 25, or 30 °C. All growth curves of L. monocytogenes were fitted to the Baranyi, modified Gompertz, and Huang models. Regardless of conditions under which cells grew, the time needed to reach 5 log CFU/g decreased with the elevated storage temperature. Experimental results showed that there were no significant differences (P > 0.05) in the maximum growth rate k (log CFU/g h(-1) ) and lag phase duration λ (h) between the cultures of L. monocytogenes with or without previous cold-adaption treatments. No distinct difference was observed in the growth pattern among 3 primary models at various storage temperatures. The growth curves of secondary modeling were fitted on an Arrhenius-type model for describing the relationship between k and temperature of the L. monocytogenes on fresh-cut cantaloupe from 10 to 30 °C. The root mean square error values of secondary models for non- and cold-adapted cells were 0.018, 0.021, and 0.024, and 0.039, 0.026, and 0.017 at the modified Gompertz, Baranyi, and Huang model, respectively, indicating that these 3 models presented the good statistical fit. This study may provide valuable information to predict the growth of L. monocytogenes on fresh-cut cantaloupes at different storage conditions. Listeriosis has occurred and increased along with the increased demand of fresh and fresh-cut fruits and vegetables. This study was conducted to predict the growth of non- and cold-adapted L. monocytogenes on fresh-cut cantaloupe at different temperature using mathematical model. These results can be helpful for risk assessments of L. monocytogenes in fresh-cut cantaloupe. This study provides valuable

  2. 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.

    Science.gov (United States)

    Bolton, D J; McMahon, C M; Doherty, A M; Sheridan, J J; McDowell, D A; Blair, I S; Harrington, D

    2000-04-01

    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.

  3. Klebsiella pneumoniae inoculants for enhancing plant growth

    Energy Technology Data Exchange (ETDEWEB)

    Triplett, Eric W. (Middleton, WI); Kaeppler, Shawn M. (Oregon, WI); Chelius, Marisa K. (Greeley, CO)

    2008-07-01

    A biological inoculant for enhancing the growth of plants is disclosed. The inoculant includes the bacterial strains Herbaspirillum seropedicae 2A, Pantoea agglomerans P101, Pantoea agglomerans P102, Klebsiella pneumoniae 342, Klebsiella pneumoniae zmvsy, Herbaspirillum seropedicae Z152, Gluconacetobacter diazotrophicus PA15, with or without a carrier. The inoculant also includes strains of the bacterium Pantoea agglomerans and K. pneumoniae which are able to enhance the growth of cereal grasses. Also disclosed are the novel bacterial strains Herbaspirillum seropedicae 2A, Pantoea agglomerans P101 and P102, and Klebsiella pneumoniae 342 and zmvsy.

  4. Klebsiella pneumoniae inoculants for enhancing plant growth

    Science.gov (United States)

    Triplett, Eric W [Middleton, WI; Kaeppler, Shawn M [Oregon, WI; Chelius, Marisa K [Greeley, CO

    2008-07-01

    A biological inoculant for enhancing the growth of plants is disclosed. The inoculant includes the bacterial strains Herbaspirillum seropedicae 2A, Pantoea agglomerans P101, Pantoea agglomerans P102, Klebsiella pneumoniae 342, Klebsiella pneumoniae zmvsy, Herbaspirillum seropedicae Z152, Gluconacetobacter diazotrophicus PA15, with or without a carrier. The inoculant also includes strains of the bacterium Pantoea agglomerans and K. pneumoniae which are able to enhance the growth of cereal grasses. Also disclosed are the novel bacterial strains Herbaspirillum seropedicae 2A, Pantoea agglomerans P101 and P102, and Klebsiella pneumoniae 342 and zmvsy.

  5. 78 FR 23901 - Interagency Risk Assessment-Listeria monocytogenes

    Science.gov (United States)

    2013-04-23

    ... Food Safety and Inspection Service Interagency Risk Assessment--Listeria monocytogenes in Retail... risk assessment (QRA), ``Interagency Risk Assessment--Listeria monocytogenes in Retail Delicatessens... and on the FSIS Web site at http://www.fsis.usda.gov/PDF/Listeria-Transcript_062309.pdf ). II....

  6. Incidence and control of Listeria monocytogenes in foods in Denmark

    DEFF Research Database (Denmark)

    Nørrung, Birgit; Andersen, Jens Kirk; Schlundt, Jørgen

    1999-01-01

    The Danish regulatory policy on Listeria monocytogenes in foods is based on the principles of HACCP and was developed using a health risk assessment approach. The Danish policy focuses examinations and criteria for L. monocytogenes in ready-to-eat foods and is based on a combination of inspection...

  7. Resistance of Listeria monocytogenes biofilms to sanitizing agents

    Science.gov (United States)

    Listeria monocytogenes is notorious for its capacity to colonize the environment and equipment of food processing facilities and to persist in the processing plant ecosystem, sometimes for decades. Such persistence is mediated by multiple attributes of L. monocytogenes, including the pathogen’s capa...

  8. Application Progress of Recombinant Attenuated Listeria monocytogenes in Tumor Immunotherapy

    Institute of Scientific and Technical Information of China (English)

    Yin Xiaojiao; Bai Lin; Yang Xu

    2015-01-01

    Much progress of application of bacterial vaccine in treatment and prevention of tumor was acquired,which showed broad prospect in clinical study of animals and humans. Listeria monocytogenes( L. monocytogenes) was considered much important by virtue of its special characteristic of biology and immunology.L. monocytogenes was ingested by professional or part-time phagocytes,survived and proliferated in the phagocytes under synergism of toxic factor secreted by itself,meanwhile,the cellular and humoral immune response was induced. Antigenic gene of specific tumor was loaded in the attenuated L. monocytogenes,which can enhance immune response of host cells. Effective cell targeted to enter tumor tissue and acted on tumor cells to induce apoptosis of tumor cells. Tumor degenerated not easy to reappear. Therefore,recombinant attenuated L. monocytogenes was a safe and effective anti-cancer vaccine vector. Now the work of researchers mainly focuses on solving practical problem in clinical application. Biological characteristics of L. monocytogenes,feasibility and superiority of L. monocytogenes as targeted vaccine vector,problem and prospect of L. monocytogenes in clinical application of anti-tumor were reviewed in this paper.

  9. Listeria monocytogenes growth limits and stress resistance mechanisms

    NARCIS (Netherlands)

    Veen, van der S.

    2008-01-01

    The food-borne pathogen Listeria monocytogenes is a Gram-positive facultative anaerobic rod, which is the causative agent of listeriosis. Due to the severity of the disease and the fact that its incidence is increasing in numerous European countries, L. monocytogenes is of great public health concer

  10. Genome sequences of Listeria monocytogenes strains with resistance to arsenic

    Science.gov (United States)

    Listeria monocytogenes frequently exhibits resistance to arsenic. We report here the draft genome sequences of eight genetically diverse arsenic-resistant L. monocytogenes strains from human listeriosis and food-associated environments. Availability of these genomes would help to elucidate the role ...

  11. Listeria monocytogenes internalizes in Romaine Lettuce grown in greenhouse conditions

    Science.gov (United States)

    Listeria monocytogenes has been implicated in a number of outbreaks involving fresh produce, including an outbreak in 2016 resulting from contaminated packaged salads. The persistence and internalization potential of L. monocytogenes in romaine lettuce was evaluated, and the persistence of two L. mo...

  12. Survival strategies of Listeria monocytogenes - roles of regulators and transporters

    NARCIS (Netherlands)

    Wemekamp-Kamphuis, H.H.

    2003-01-01

    Outbreaks of the food-borne pathogen Listeria monocytogenes are mainly associated with ready-to-eatfoods. Survival strategies of L. monocytogenes in relation to minimally processed foods were studied.

  13. Roche/BIOTECON Diagnostics LightCycler foodproof L. monocytogenes detection kit in combination with ShortPrep foodproof II Kit. Performance-Tested Method 070401.

    Science.gov (United States)

    Junge, Benjamin; Berghof-Jäger, Kornelia

    2006-01-01

    A method was developed for the detection of L. monocytogenes in food based on real-time polymerase chain reaction (PCR). This advanced PCR method was designed to reduce the time needed to achieve results from PCR reactions and to enable the user to monitor the amplification of the PCR product simultaneously, in real-time. After DNA isolation using the Roche/BIOTECON Diagnostics ShortPrep foodproof II Kit (formerly called Listeria ShortPrep Kit) designed for the rapid preparation of L. monocytogenes DNA for direct use in PCR, the real-time detection of L. monocytogenes DNA is performed by using the Roche/BIOTECON Diagnostics LightCycler foodproof L. monocytogenes Detection Kit. This kit provides primers and hybridization probes for sequence-specific detection, convenient premixed reagents, and different controls for reliable interpretation of results. For repeatability studies, 20 different foods, covering the 15 food groups recommended from the AOAC Research Institute (AOAC RI) for L. monocytogenes detection were analyzed: raw meats, fresh produce/vegetables, processed meats, seafood, egg and egg products, dairy (cultured/noncultured), spices, dry foods, fruit/juices, uncooked pasta, nuts, confectionery, pet food, food dyes and colorings, and miscellaneous. From each food 20, samples were inoculated with a low level (1-10 colony-forming units (CFU)/25 g) and 20 samples with a high level (10-50 CFU/25 g) of L. monocytogenes. Additionally, 5 uninoculated samples were prepared from each food. The food samples were examined with the test kits and in correlation with the cultural methods according to U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) or U.S. Department of Agriculture (USDA)/Food Safety and Inspection Service (FSIS) Microbiology Laboratory Guidebook. After 48 h of incubation, the PCR method in all cases showed equal or better results than the reference cultural FDA/BAM or USDA/FSIS methods. Fifteen out of 20 tested food types

  14. Effect of lactic acid bacteria on extention of shelf life and growth of Listeria monocytogenes in beef steaks stored in CO2- rich atmosphere Efeito de bactérias láticas na extensâo da vida de parateleira e multiplicação de Listeria monocytogenes em fatias de carne bovina armazenadas em atmosfera rica em CO2

    Directory of Open Access Journals (Sweden)

    Djamel Djenane

    2005-12-01

    Full Text Available Beef steaks were inoculated with one or other of two protective strains of lactic acid bacteria (bacteriocinogenic Lactobacillus sakei CTC 372 or the uncharacterized Lactobacillus CTC 711, and stored under modified atmospheres (20-40% CO2. Inoculation of meat with LAB inhibited growth of the spoilage bacteria. Neither CO2 in the pack atmosphere or inoculation with protective strains, nor a combination of both, affected formation of metmyoglobin or the development of off-odours. The formation of metmyoglobin in meat pigments and the sensory odour scores were compatible to those of fresh meat which had not undergone either oxidative deterioration or microbial spoilage. Listeria monocytogenes was inhibited in broth by meat surface microbiota containing the protective strains. With initial numbers of 5.6 log cfu mL-1, after 7 days incubation at 3ºC, L. monocytogenes were recovered at log mean numbers of 2.8 log cfu mL-1 when no protective strain was present. At 8ºC, the numbers of L. monocytogenes were reduced by about 2.5 or 1.5 log mL-1 in the presence of Lb. sakei CTC 372 or Lb. CTC 711, respectively. At 25ºC, the numbers of L. monocytogenes recovered from broth containing either protective strain were about 5 log lower than the numbers recovered from broth containing L. monocytogenes only.Fatias de carne bovina foram inoculadas com uma de duas bactérias láticas protetoras (Lactobacillus sakei CTC 372 bacteriocinogênica e Lactobacillus CTC 711 não caracterizado e armazenadas em atmosfera modificada (20-40% CO2. A inoculação da carne com bactérias láticas protetoras inibiu a multiplicação de bactérias deteriorantes. O CO2 da atmosfera e/ou a presença de bactérias láticas não causou a formação de metmioglobina ou de odores indesejáveis. A formação de metmioglobina e as características sensoriais foram equivalentes às apresentadas por carne fresca não deteriorada e não submetida a tratamento. A multiplicação de Listeria

  15. [Studies on the effect of combined treatment of irradiation with vacuum packaging on ready-to-eat meat products contaminated with Listeria monocytogenes and spoilage bacteria].

    Science.gov (United States)

    Fu, Ping; Ji, Rong; Li, Yuwei; Li, Yanjun

    2002-08-01

    Altogether one hundred and fifty samples of Beijing roast duck, roast chicken and cooked meat products inoculated with approximately 1.5 x 10(3)-2.3 x 10(3) cfu/g L. monocytogenes are packed under vacuum and are irradiated with 60Co radiation at doses of 1.0, 2.0, 2.5 and 3 kGy. The results showed that L. monocytogenes in samples can be eliminated by a dose of 2.5 kGy. The resistance of the model strain 54004 to irradiation is stranger than three isolates (X20, G4 and g2). In addition, the spoilage bacteria in 150 samples of roast duck, roast chicken and cooked meat products can be killed at doses of 10.15 and 20 kGy, respectively.

  16. Evaluation of two loop-mediated isothermal amplification methods for the detection of Salmonella Enteritidis and Listeria monocytogenes in artificially contaminated ready-to-eat fresh products

    Directory of Open Access Journals (Sweden)

    Angeliki Birmpa

    2015-08-01

    Full Text Available In the present study, the effectiveness of two loop-mediated isothermal amplification (LAMP assays was evaluated. Samples of romaine lettuce, strawberries, cherry tomatoes, green onions and sour berries were inoculated with known dilutions (100-108 CFU/g of produce of S. Enteritidis and L. monocytogenes. With LAMP assay, pathogens can be detected in less than 60 min. The limits of detection of S. Enteritidis and L. monocytogenes depended on the food sample tested and on the presence of enrichment step. After enrichment steps, all food samples were found positive even at low initial pathogen levels. The developed LAMP, assays, are expected to become a valuable, robust, innovative, powerful, cheap and fast monitoring tool, which can be extensively used for routine analysis, and screening of contaminated foods by the food industry and the Public Food Health Authorities.

  17. Phosphorylation of inositol 1,4,5-trisphosphate analogues by 3-kinase and dephosphorylation of inositol 1,3,4,5-tetrakisphosphate analogues by 5-phosphatase

    NARCIS (Netherlands)

    Dijken, Peter van; Lammers, Aleida A.; Ozaki, Shoichiro; Potter, Barry V.L.; Erneux, Christophe; Haastert, Peter J.M. van

    1994-01-01

    A series of P-32-labeled D-myo-inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P-4] analogues was enzymically prepared from the corresponding D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P-3] analogues using recombinant rat brain Ins(1,4,5)P-3 3-kinase and [gamma-P-32]ATP. Ins(1,4,5)P-3 analogues

  18. Prevalence of Listeria monocytogenes in Idiazabal cheese Prevalencia de Listeria monocytogenes en queso Idiazabal

    Directory of Open Access Journals (Sweden)

    E. Arrese

    2012-12-01

    Full Text Available Introduction: Raw-milk cheese has been identified in risk assessment as a food of greater concern to public health due to listeriosis. Objective: To determine the prevalence and levels of Listeria monocytogenes in semi-hard Idiazabal cheese manufactured by different producers in the Basque Country at consumer level. Methodology: A total of 51 Idiazabal cheese samples were obtained from 10 separate retail establishments, chosen by stratified random sampling. Samples were tested using the official standard ISO procedure 11290-1 for detection and enumeration methods. Results and conclusion: All cheese samples tested negative for L. monocytogenes. However, 9.8% tested positive for Listeria spp., different from L. monocytogenes. Positive samples came from two brands, two were natural and three were smoked. The presence of Listeria spss. suggests that the cheese making process and the hygiene whether at milking or during cheese making could be insufficient.Introducción: Listeria monocytogenes se ha asociado a quesos elaborados a partir de leche cruda, lo que supone un importante riesgo de salud pública debido a la listeriosis. Objetivo: Estudiar la prevalencia y los niveles de L. monocytogenes en quesos Idiazabal semi-curados de distintos productores del País Vasco, a nivel de consumidor. Metodología: Se analizaron 51 muestras de queso Idiazabal procedentes de 10 establecimientos de venta al público; el muestreo fue aleatorio y estratificado. Los análisis se hicieron según el método de detección y de enumeración del procedimiento estandarizado ISO 11290-1. Resultados y conclusión: Todas las muestras dieron negativo para L. monocytogenes. Sin embargo, el 9,8% dio positivo para Listeria spp., distinta de L. monocytogenes. Las muestras positivas procedían de dos marcas, dos eran quesos naturales y tres ahumados. La presencia de Listeria spss. sugiere que el procesado del queso y la higiene durante el ordeño o durante la fabricación podr

  19. Inoculation of chromium white cast iron

    Directory of Open Access Journals (Sweden)

    D. Kopyciński

    2009-01-01

    Full Text Available It has been proved that an addition of boron carbide introduced as an inoculant to the chromium white cast iron changes the structureof castings. Castings after inoculation revealed a different structure with numerous grains. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

  20. Automatic surface inoculation of agar trays.

    Science.gov (United States)

    Wilkins, J. R.; Mills, S. M.; Boykin, E. H.

    1972-01-01

    Description of a machine and technique for the automatic inoculation of a plastic tray containing agar media with a culture, using either a conventional inoculation loop or a cotton swab. The design of the machine is simple, it is easy to use, and it relieves the operator from the manual task of streaking cultures. The described technique makes possible the visualization of the overall qualitative and, to some extent, quantitative relationships of various bacterial types in a sample tested.

  1. New inoculants on maize silage fermentation

    Directory of Open Access Journals (Sweden)

    Fábia Giovana do Val de Assis

    2014-08-01

    Full Text Available The objective of this study was to evaluate the effect of bacterial inoculants at two inoculation rates on chemical and biological characteristics of maize silage. The treatments consisted of two inoculating rates (5 and 6 log cfu g-1 of forage for each strain of lactic acid bacteria (LAB identified as Lactobacillus buchneri, L. hilgardii, or L. plantarum. The maize was ensiled in experimental PVC silos. Samples were taken for the determination of the contents of dry matter (DM, crude protein (CP, neutral detergent fiber (NDF, water-soluble carbohydrates (WSC, organic acids and alcohols, for the evaluation of the populations of lactic acid bacteria, yeasts, filamentous fungi, and for the determination of pH values during ensilage and after 30 or 90 days of fermentation. The doses of inoculants did not promote significant differences on the evaluated characteristics. There was effect of inoculants on acetic acid, 1.2-propanediol, LAB population, filamentous fungi, and pH value. No significant influence of the treatments with inoculants was observed in the variables DM, WSC, CP, lactic acid concentrations, or ethanol. The maximum temperature, i.e., the time to achieve the maximum temperature (TMT and aerobic stability (AS, was not influencied by treatments. However, a decrease in maximum temperature, an increase in TMT, and improvement in the AS were observed after 90 days of fermentation. These results proved the advantage of microbial inoculation. The treatments influenced LAB populations and filamentous fungi, but no effect was observed on the yeast population. The best inoculation dose is 6 cfu g-1 of forage because it provides higher reduction of filamentous fungi in maize silage, thereby decreasing the aerobic deterioration by these microorganisms.

  2. Thermal conductivity of Cu–4.5 Ti alloy

    Indian Academy of Sciences (India)

    S Nagarjuna

    2004-02-01

    The thermal conductivity (TC) of peak aged Cu–4.5 wt% Ti alloy was measured at different temperatures and studied its variation with temperature. It was found that TC increased with increasing temperature. Phonon and electronic components of thermal conductivity were computed from the results. The alloy exhibits an electronic thermal conductivity of 46.45 W/m.K at room temperature. The phonon thermal conductivity decreased with increasing temperature from 17.6 at 0 K to 1.75 W/m.K at 298 K, which agrees with literature that the phonon component of thermal conductivity is insignificant at room temperature.

  3. PATOGENESIS DE Listeria monocytogenes, MICROORGANISMO ZOONOTICO EMERGENTE.

    OpenAIRE

    Torres, Kirvis; Sierra, Sara; Potou, Raul; Carrascal, Ana; Mercado, Marcela

    2005-01-01

    Listeria monocytogenes además de ser un paradigma para la investigación inmunológica se ha convertido en sistema modelo apropiado para el análisis de los mecanismos moleculares del parasitismo intracelular de otras bacterias. Investigadores en el área de la inmunología se interesaron en este microorganismo cuando se reconoció el riesgo que representaba para la salud pública y la seguridad en la industria de alimentos. Desde mediados de los años 80’s se ha investigado la biología molecular de ...

  4. Growth and inactivation of Salmonella enterica and Listeria monocytogenes in broth and validation in ground pork meat during simulated home storage abusive temperature and home pan-frying

    Directory of Open Access Journals (Sweden)

    Xiang eWang

    2015-10-01

    Full Text Available Ground pork meat with natural microbiota and inoculated with low initial densities (1-10 or 10-100 CFU/g of Salmonella enterica or Listeria monocytogenes was stored under abusive temperature at 10°C and thermally treated by a simulated home pan-frying procedure. The growth and inactivation characteristics were also evaluated in broth. In ground pork meat, the population of S. enterica increased by less than one log after 12-days of storage at 10°C, whereas L. monocytogenes increased by 2.3 to 2.8 log units. No unusual intrinsic heat resistance of the pathogens was noted when tested in broth at 60°C although shoulders were observed on the inactivation curves of L. monocytogenes. After growth of S. enterica and L. monocytogenes at 10°C for 5 days to levels of 1.95 log CFU/g and 3.10 log CFU/g, respectively, in ground pork meat, their inactivation in the burger subjected to a simulated home pan-frying was studied. After thermal treatment S. enterica was undetectable but L. monocytogenes was recovered in three out of six of the 25 g burger samples. Overall, the present study shows that data on growth and inactivation of broths are indicative but may underestimate as well as overestimate behavior of pathogens and thus need confirmation in food matrix conditions to assess food safety in reasonably foreseen abusive conditions of storage and usual home pan-frying of of meat burgers in Belgium.

  5. Antimicrobial effect of electrolyzed oxidizing water against Escherichia coli O157:H7 and Listeria monocytogenes on fresh strawberries (Fragaria x ananassa).

    Science.gov (United States)

    Udompijitkul, P; Daeschel, M A; Zhao, Y

    2007-11-01

    Antibacterial activity of electrolyzed oxidizing (EO) water prepared from 0.05% or 0.10% (w/v) sodium chloride (NaCl) solutions against indigenous bacteria associated with fresh strawberries (Fragaria x ananassa) was evaluated. The efficacy of EO water and sodium hypochlorite (NaOCl) solution in eliminating and controlling the growth of Listeria monocytogenes and Escherichia coli O157:H7 inoculated onto strawberries stored at 4 +/- 1 degrees C up to 15 d was investigated at exposure time of 1, 5, or 10 min. Posttreatment neutralization of fruit surfaces was also determined. More than 2 log(10) CFU/g reductions of aerobic mesophiles were obtained in fruits washed for 10 or 15 min in EO water prepared from 0.10% (w/v) NaCl solution. Bactericidal activity of the disinfectants against L. monocytogenes and E. coli O157:H7 was not affected by posttreatment neutralization, and increasing exposure time did not significantly increase the antibacterial efficacy against both pathogens. While washing fruit surfaces with distilled water resulted in 1.90 and 1.27 log(10) CFU/mL of rinse fluid reduction of L. monocytogenes and E. coli O157:H7, respectively, >/= 2.60 log(10) CFU/mL of rinse fluid reduction of L. monocytogenes and up to 2.35 and 3.12 log(10) CFU/mL of rinse fluid reduction of E. coli O157:H7 were observed on fruit surfaces washed with EO water and NaOCl solution, respectively. Listeria monocytogenes and E. coli O157:H7 populations decreased over storage regardless of prior treatment. However, EO water and aqueous NaOCl did not show higher antimicrobial potential than water treatment during refrigeration storage.

  6. Analysing and modelling the growth behaviour of Listeria monocytogenes on RTE cooked meat products after a high pressure treatment at 400 MPa.

    Science.gov (United States)

    Hereu, A; Dalgaard, P; Garriga, M; Aymerich, T; Bover-Cid, S

    2014-09-01

    Various predictive models are available for high pressure inactivation of Listeria monocytogenes in food, but currently available models do not consider the growth kinetics of surviving cells during the subsequent storage of products. Therefore, we characterised the growth of L. monocytogenes in sliced cooked meat products after a pressurization treatment. Two inoculum levels (10(7) or 10(4) CFU/g) and two physiological states before pressurization (freeze-stressed or cold-adapted) were evaluated. Samples of cooked ham and mortadella were inoculated, high pressure processed (400 MPa, 5 min) and subsequently stored at 4, 8 and 12 °C. The Logistic model with delay was used to estimate lag phase (λ) and maximum specific growth rate (μmax) values from the obtained growth curves. The effect of storage temperature on μmax and λ was modelled using the Ratkowsky square root model and the relative lag time (RLT) concept. Compared with cold-adapted cells the freeze-stressed cells were more pressure-resistant and showed a much longer lag phase during growth after the pressure treatment. Interestingly, for high-pressure inactivation and subsequent growth, the time to achieve a concentration of L. monocytogenes 100-fold (2-log) higher than the cell concentration prior to the pressure treatment was similar for the two studied physiological states of the inoculum. Two secondary models were necessary to describe the different growth behaviour of L. monocytogenes on ready-to-eat cooked ham (lean product) and mortadella (fatty product). This supported the need of a product-oriented approach to assess growth after high pressure processing. The performance of the developed predictive models for the growth of L. monocytogenes in high-pressure processed cooked ham and mortadella was evaluated by comparison with available data from the literature and by using the Acceptable Simulation Zone approach. Overall, 91% of the relative errors fell into the Acceptable Simulation Zone

  7. Roles of reactive oxygen species and heme oxygenase-1 in modulation of alveolar macrophage-mediated pulmonary immune responses to Listeria monocytogenes by diesel exhaust particles.

    Science.gov (United States)

    Yin, Xuejun J; Ma, Jane Y C; Antonini, James M; Castranova, Vincent; Ma, Joseph K H

    2004-11-01

    Diesel exhaust particles (DEP) have been shown to suppress alveolar macrophage (AM)-mediated pulmonary immune responses to Listeria monocytogenes in vivo. In this study, effects of DEP-derived reactive oxygen species (ROS) and heme oxygenase (HO)-1 on AM-mediated immune responses to L. monocytogenes were investigated. Brown Norway rats were intratracheally inoculated with 100,000 L. monocytogenes, and AM were isolated at 7 days post-infection. Exposure to DEP or their organic extract (eDEP), but not the washed DEP (wDEP) or carbon black, increased intracellular ROS and HO-1 expression in AM. Induction of ROS and HO-1 by eDEP was partially reversed by alpha-naphthoflavone, a cytochrome P450 1A1 inhibitor, and totally blocked by N-acetylcysteine. In addition, exposure to eDEP, but not wDEP, inhibited lipopolysacchride-stimulated secretion of tumor necrosis factor-alpha (TNF-alpha) and interleukin-12 (IL-12), but augmented production of IL-10 by AM. Kinetic studies showed that modulation of cytokines by eDEP was preceded by ROS and HO-1 induction. Furthermore, pretreatment of AM with superoxide dismutase (SOD) or zinc protoporphrin IX (Znpp), which attenuated eDEP-induced HO-1 expression/activity, substantially inhibited eDEP effect on IL-10. Finally, direct stimulation with pyrogallol (PYR), a superoxide donor, upregulated HO-1 and IL-10 but decreased secretion of IL-12 in L. monocytogenes-infected AM. These results show that DEP, through eDEP-mediated ROS, induce HO-1 expression and IL-10 production and at the same time inhibit AM production of TNF-alpha and IL-12 to dampen the host immune responses. The results also suggest that HO-1 may play an important role in regulating production of IL-10 by DEP-exposed and L. monocytogenes-infected AM.

  8. Human isolates of Bartonella tamiae induce pathology in experimentally inoculated immunocompetent mice

    Directory of Open Access Journals (Sweden)

    Kosoy Michael Y

    2010-07-01

    Full Text Available Abstract Background Bartonella tamiae, a newly described bacterial species, was isolated from the blood of three hospitalized patients in Thailand. These patients presented with headache, myalgia, anemia, and mild liver function abnormalities. Since B. tamiae was presumed to be the cause of their illness, these isolates were inoculated into immunocompetent mice to determine their relative pathogenicity in inducing manifestations of disease and pathology similar to that observed in humans. Methods Three groups of four Swiss Webster female mice aged 15-18 months were each inoculated with 106-7 colony forming units of one of three B. tamiae isolates [Th239, Th307, and Th339]. A mouse from each experimental group was sampled at 3, 4, 5 and 6 weeks post-inoculation. Two saline inoculated age-matched controls were included in the study. Samples collected at necropsy were evaluated for the presence of B. tamiae DNA, and tissues were formalin-fixed, stained with hematoxylin and eosin, and examined for histopathology. Results Following inoculation with B. tamiae, mice developed ulcerative skin lesions and subcutaneous masses on the lateral thorax, as well as axillary and inguinal lymphadenopathy. B. tamiae DNA was found in subcutaneous masses, lymph node, and liver of inoculated mice. Histopathological changes were observed in tissues of inoculated mice, and severity of lesions correlated with the isolate inoculated, with the most severe pathology induced by B. tamiae Th239. Mice inoculated with Th239 and Th339 demonstrated myocarditis, lymphadenitis with associated vascular necrosis, and granulomatous hepatitis and nephritis with associated hepatocellular and renal necrosis. Mice inoculated with Th307 developed a deep dermatitis and granulomas within the kidneys. Conclusions The three isolates of B. tamiae evaluated in this study induce disease in immunocompetent Swiss Webster mice up to 6 weeks after inoculation. The human patients from whom these

  9. Evaluating the growth of Listeria monocytogenes in refrigerated ready-to-eat frankfurters: influence of strain, temperature, packaging, lactate and diacetate, and background microflora.

    Science.gov (United States)

    Pal, Amit; Labuza, Theodore P; Diez-Gonzalez, Francisco

    2008-09-01

    This research was conducted to study the growth of Listeria monocytogenes inoculated on frankfurters stored at different conditions as a basis for a safety-based consume by shelf life date label. Three L. monocytogenes strains were separately inoculated at 10 to 20 CFU/cm2 onto frankfurters that were previously formulated with or without high pressure and with or without added 2% potassium lactate (PL) and 0.2% sodium diacetate (SD). Inoculated frankfurters were air or vacuum packaged; stored at 4, 8, or 12 degrees C; and L. monocytogenes and psychrotrophic plate counts were determined for 90, 60, and 45 days, respectively, or until the stationary phase was reached. The data (log CFU per square centimeter versus time) were fitted using the Baranyi-Roberts model to determine maximum growth rates and lag-phase time. The maximum growth rates and the lag time under each growth condition were used to calculate the time to reach 100-fold the initial Listeria population. In frankfurters lacking PL and SD, the count of all strains increased by 2 log after 18 to 50 days at 4 degrees C and 4 to 13 days at 8 degrees C. The growth was inhibited at 4 and 8 degrees C in frankfurters containing PL and SD, but one ribotype was capable of growing, with the time to reach 100-fold the initial Listeria population ranging from 19 to 35 days at 12 degrees C. In most cases, the time to reach 100-fold the initial Listeria population of L. monocytogenes was significantly longer in vacuum-packaged frankfurters as compared with air-packaged samples. Inclusion of PL and SD also inhibited the growth of psychrotrophs, but at all temperatures the psychrotrophic plate counts were greater than 4 log CFU/cm2 at the end of the experiments. These results indicated that despite the use of antimicrobials, certain L. monocytogenes strains could be capable of growing under storage-abuse conditions. Growth kinetics data could be useful for establishing a shelf life date label protocol under different

  10. Inhibition of Listeria monocytogenes by Enterococcus mundtii isolated from soil.

    Science.gov (United States)

    Bigwood, T; Hudson, J A; Cooney, J; McIntyre, L; Billington, C; Heinemann, J A; Wall, F

    2012-12-01

    Two bacterial isolates with inhibitory activity against Listeria monocytogenes and Enterococcus faecalis were obtained from soil. Genotypic and phenotypic characterization identified them as Enterococcus mundtii, a species whose ability to compete with L. monocytogenes is relatively unexplored compared to other members of the genus. The thermal stability of the inhibitory factor and its sensitivity to proteolytic enzymes indicate that it is most likely a bacteriocin. Both isolates grew at comparable rates to L. monocytogenes at 5 °C and 10 °C in vitro. One isolate killed L. monocytogenes when it reached concentrations of 10(6)-10(8) CFU ml(-1). Minimum inocula of 10(6) and 10(5) CFU ml(-1) of E. mundtii were required to reduce and maintain L. monocytogenes concentrations beneath the level of detection at 5 °C and 10 °C, respectively. In situ experiments at 5 °C showed that E. mundtii inhibited the growth of L. monocytogenes on vacuum-packed cold smoked salmon during its four week shelf life. E. mundtii could, therefore, control the growth of L. monocytogenes at low temperatures, indicating a potential application in controlling this pathogen in chilled foods. To control growth of Listeria, the concentration of E. mundtii needs to be high, but it is possible that a purified bacteriocin could be used to achieve the same effect.

  11. Incorporation of Listeria monocytogenes strains in raw milk biofilms.

    Science.gov (United States)

    Weiler, Christiane; Ifland, Andrea; Naumann, Annette; Kleta, Sylvia; Noll, Matthias

    2013-02-01

    Biofilms develop successively on devices of milk production without sufficient cleaning and originate from the microbial community of raw milk. The established biofilm matrices enable incorporation of pathogens like Listeria monocytogenes, which can cause a continuous contamination of food processing plants. L. monocytogenes is frequently found in raw milk and non-pasteurized raw milk products and as part of a biofilm community in milk meters and bulk milk tanks. The aim of this study was to analyze whether different L. monocytogenes strains are interacting with the microbial community of raw milk in terms of biofilm formation in the same manner, and to identify at which stage of biofilm formation a selected L. monocytogenes strain settles best. Bacterial community structure and composition of biofilms were analyzed by a cloning and sequencing approach and terminal restriction fragment length polymorphism analysis (T-RFLP) based on the bacterial 16S rRNA gene. The chemical composition of biofilms was analyzed by Fourier transform infrared spectroscopy (FTIR), while settled L. monocytogenes cells were quantified by fluorescence in situ hybridization (FISH). Addition of individual L. monocytogenes strains to raw milk caused significant shifts in the biofilm biomass, in the chemical as well as in the bacterial community composition. Biofilm formation and attachment of L. monocytogenes cells were not serotype but strain specific. However, the added L. monocytogenes strains were not abundant since mainly members of the genera Citrobacter and Lactococcus dominated the bacterial biofilm community. Overall, added L. monocytogenes strains led to a highly competitive interaction with the raw milk community and triggered alterations in biofilm formation.

  12. Listeria monocytogenes as a vector for anti-cancer therapies.

    LENUS (Irish Health Repository)

    Tangney, Mark

    2012-01-31

    The intracellular pathogen Listeria monocytogenes represents a promising therapeutic vector for the delivery of DNA, RNA or protein to cancer cells or to prime immune responses against tumour-specific antigens. A number of biological properties make L. monocytogenes a promising platform for development as a vector for either gene therapy or as an anti-cancer vaccine vector. L. monocytogenes is particularly efficient in mediating internalization into host cells. Once inside cells, the bacterium produces specific virulence factors which lyse the vaculolar membrane and allow escape into the cytoplasm. Once in the cytosol, L. monocytogenes is capable of actin-based motility and cell-to-cell spread without an extracellular phase. The cytoplasmic location of L. monocytogenes is significant as this potentiates entry of antigens into the MHC Class I antigen processing pathway leading to priming of specific CD8(+) T cell responses. The cytoplasmic location is also beneficial for the delivery of DNA (bactofection) by L. monocytogenes whilst cell-to-cell spread may facilitate access of the vector to cells throughout the tumour. Several preclinical studies have demonstrated the ability of L. monocytogenes for intracellular gene or protein delivery in vitro and in vivo, and this vector has also displayed safety and efficacy in clinical trial. Here, we review the features of the L. monocytogenes host-pathogen interaction that make this bacterium such an attractive candidate with which to induce appropriate therapeutic responses. We focus primarily upon work that has led to attenuation of the pathogen, demonstrated DNA, RNA or protein delivery to tumour cells as well as research that shows the efficacy of L. monocytogenes as a vector for tumour-specific vaccine delivery.

  13. Beginning ASP.NET 4.5 in C#

    CERN Document Server

    MacDonald, Matthew

    2012-01-01

    This book is the most comprehensive and up to date introduction to ASP.NET ever written. Focussing solely on C#, with no code samples duplicated in other languages, award winning author Matthew MacDonald introduces you to the very latest thinking and best practices for the ASP.NET 4.5 technology.Assuming no prior coding experience, you'll be taught everything you need to know from the ground up.  Starting from first principals, you'll learn the skills you need to be an effective ASP.NET developer who is ready to progress to more sophisticated projects and professional work. You'll be taught ho

  14. Beginning ASP.NET 4.5 in VB

    CERN Document Server

    MacDonald, Matthew

    2012-01-01

    This book is the most comprehensive and up to date introduction to ASP.NET ever written. Focusing solely on Visual Basic, with no code samples duplicated in other languages, award winning author Matthew MacDonald introduces you to the very latest thinking and best practices for the ASP.NET 4.5 technology.Assuming no prior coding experience, you'll be taught everything you need to know from the ground up.  Starting from first principals, you'll learn the skills you need to be an effective ASP.NET developer who is ready to progress to more sophisticated projects and professional work.You'll be t

  15. N,N′-Dicyclohexylnaphthalene-1,8;4:5-dicarboximide

    Directory of Open Access Journals (Sweden)

    Manju Rajeswaran

    2008-09-01

    Full Text Available The title compound, C26H26N2O4, synthesized by the reaction of naphthalene-1,4,5,8-tetracarboxylic acid anhydride and cyclohexylamine, exhibits good n-type semiconducting properties. Accordingly, thin-film transistor devices comprising this compound show n-type behavior with high field-effect electron moblity ca 6 cm2/Vs [Shukla, Nelson, Freeman, Rajeswaran, Ahearn, Meyer & Carey(2008. Chem. Mater. Submitted]. The asymmetric unit comprises one-quarter of the centrosymmetric molecule in which all but two methylene C atoms of the cyclohexane ring lie on a mirror plane; the point-group symmetry is 2/m. The naphthalenediimide unit is strictly planar, and the cyclohexane rings adopt chair conformations with the diimide unit in an equatorial position on each ring.

  16. Implementing and Evaluating Variable Soil Thickness in the Community Land Model, Version 4.5 (CLM4.5)

    Energy Technology Data Exchange (ETDEWEB)

    Brunke, Michael A.; Broxton, Patrick; Pelletier, Jon; Gochis, David; Hazenberg, Pieter; Lawrence, David M.; Leung, L. Ruby; Niu, Guo-Yue; Troch, Peter A.; Zeng, Xubin

    2016-05-01

    One of the recognized weaknesses of land surface models as used in weather and climate models is the assumption of constant soil thickness due to the lack of global estimates of bedrock depth. Using a 30 arcsecond global dataset for the thickness of relatively porous, unconsolidated sediments over bedrock, spatial variation in soil thickness is included here in version 4.5 of the Community Land Model (CLM4.5). The number of soil layers for each grid cell is determined from the average soil depth for each 0.9° latitude x 1.25° longitude grid cell. Including variable soil thickness affects the simulations most in regions with shallow bedrock corresponding predominantly to areas of mountainous terrain. The greatest changes are to baseflow, with the annual minimum generally occurring earlier, while smaller changes are seen in surface fluxes like latent heat flux and surface runoff in which only the annual cycle amplitude is increased. These changes are tied to soil moisture changes which are most substantial in locations with shallow bedrock. Total water storage (TWS) anomalies do not change much over most river basins around the globe, since most basins contain mostly deep soils. However, it was found that TWS anomalies substantially differ for a river basin with more mountainous terrain. Additionally, the annual cycle in soil temperature are affected by including realistic soil thicknesses due to changes to heat capacity and thermal conductivity.

  17. LACTIC FLORA-LISTERIA MONOCYTOGENES INTERACTION

    Directory of Open Access Journals (Sweden)

    S. Colombo

    2012-08-01

    Full Text Available The EC Regulation 2073/2005 (1 requires that food processors evaluate the capability of ready-to-use (RTE products to support the development of Listeria monocytogenes when their pH and aW values are favourable to the growth of this microorganism. It is renown that the lactic flora plays an important role in many different foods, both from a technological and a food safety standpoint. This study was aimed to observe the behaviour and the potential anti-Listeria effect of some natural lactic flora present in Italian liver patè crostini (chicken heart and liver, anchovies, onions, capers, starch, no added preservatives through the Combase Predictor – Max Growth Rate predictive software. The natural lactic flora of the crostini demonstrated a variable capability to inhibit the growth of Listeria monocytogenes which depends upon : the concentration of the lactic flora at the beginning of the shelf life period and the subsequent lag phase, the possible release of anti-Listeria substances, and the maximum growth rate.

  18. Silver as antibacterial towards Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Simone eBelluco

    2016-03-01

    Full Text Available Listeria monocytogenes is a serious foodborne pathogen that can contaminate food during processing and can grow during food shelf-life. New types of safe and effective food contact materials embedding antimicrobial agents, like silver, can play an important role in the food industry. The present work aimed at evaluating the in vitro growth kinetics of different strains of L. monocytogenes in the presence of silver, both in its ionic and nano form. The antimicrobial effect was determined by assaying the number of culturable bacterial cells, which formed colonies after incubation in the presence of silver nanoparticles (AgNPs or silver nitrate (AgNO3. Ionic release experiments were performed in parallel. A different reduction of bacterial viability between silver ionic and nano forms was observed, with a time delayed effect exerted by AgNPs. An association between antimicrobial activity and ions concentration was shown by both silver chemical forms, suggesting the major role of ions in the antimicrobial mode of action.

  19. Evaluation of bacteriocin-producing Lactobacillus sakei 1 against Listeria monocytogenes 1/2a growth and haemolytic activity Avaliação de Lactobacillus sakei 1 produtor de bacteriocina frente a Listeria monocytogenes 1/2a e sua atividade hemolítica

    Directory of Open Access Journals (Sweden)

    Rafael C.R. Martinez

    2005-03-01

    Full Text Available Bacteriocin-producing Lactobacillus sakei 1 was cultivated in Brain-Heart Infusion broth (24 h at 25ºC. The culture supernatant was neutralized, filter sterilized and used to test the activity of bacteriocin against Listeria monocytogenes 1/2a, at 8ºC and 15ºC. Non-bacteriocinogenic Lactobacillus sakei ATCC 15521 was used as a negative control. L. monocytogenes 1/2a was inoculated in culture supernatant medium from L. sakei 1 and L. sakei ATCC 15521 and the listerial populations were determined after 0, 5 and 10 days. The bacteriocin production was quantified as arbitrary units per mL (AU/mL using agar antagonism test. Additionally, to investigate if L. monocytogenes virulence pattern could be changed after bactericion exposure, the ability of L. monocytogenes to cause haemolysis in sheep red blood cells was determined, before and after exposure to bacteriocin at 8ºC. In the presence of the antimicrobial peptide, at 8ºC, L. monocytogenes population decreased, but growth of resistant cells was observed. At 15ºC, there was no difference between test and control. Furthermore, the haemolytic activity of L. monocytogenes 1/2a was not altered by exposure to L. sakei 1 bacteriocin, which suggests no change in its virulence pattern.Lactobacillus sakei 1 produtor de bacteriocina foi cultivado em caldo Infusão Cérebro-Coração por 24h a 25ºC. O sobrenadante da cultura foi neutralizado, esterilizado por filtração e usado para testar a atividade da bacteriocina frente a Listeria monocytogenes 1/2a, a 8ºC e 15ºC. Lactobacillus sakei ATCC 15521 não bacteriocinogênico, foi utilizado como controle negativo. L. monocytogenes 1/2a foi inoculada no sobrenadante da cultura de L.sakei 1 e L. sakei ATCC 15521 e as populações listeriais foram determinadas após 0, 5 e 10 dias. A produção de bacteriocina foi quantificada como unidades arbitrárias por mL (UA/mL, utilizando-se o teste de antagonismo em ágar. Adicionalmente, para investigar se o padr

  20. Prevalence and challenge tests of Listeria monocytogenes in Belgian produced and retailed mayonnaise-based deli-salads, cooked meat products and smoked fish between 2005 and 2007.

    Science.gov (United States)

    Uyttendaele, M; Busschaert, P; Valero, A; Geeraerd, A H; Vermeulen, A; Jacxsens, L; Goh, K K; De Loy, A; Van Impe, J F; Devlieghere, F

    2009-07-31

    Processed ready-to-eat (RTE) foods with a prolonged shelf-life under refrigeration are at risk products for listeriosis. This manuscript provides an overview of prevalence data (n=1974) and challenge tests (n=299) related to Listeria monocytogenes for three categories of RTE food i) mayonnaise-based deli-salads (1187 presence/absence tests and 182 challenge tests), ii) cooked meat products (639 presence/absence tests and 92 challenge tests), and iii) smoked fish (90 presence/absence tests and 25 challenge tests), based on data records obtained from various food business operators in Belgium in the frame of the validation and verification of their HACCP plans over the period 2005-2007. Overall, the prevalence of L. monocytogenes in these RTE foods in the present study was lower compared to former studies in Belgium. For mayonnaise-based deli-salads, in 80 out of 1187 samples (6.7%) the pathogen was detected in 25 g. L. monocytogenes positive samples were often associated with smoked fish deli-salads. Cooked meat products showed a 1.1% (n=639) prevalence of the pathogen. For both food categories, numbers per gram never exceeded 100 CFU. L. monocytogenes was detected in 27.8% (25/90) smoked fish samples, while 4/25 positive samples failed to comply to the 100 CFU/g limit set out in EU Regulation 2073/2005. Challenge testing showed growth potential in 18/182 (9.9%) deli-salads and 61/92 (66%) cooked meat products. Nevertheless, both for deli-salads and cooked meat products, appropriate product formulation and storage conditions based upon hurdle technology could guarantee no growth of L. monocytogenes throughout the shelf-life as specified by the food business operator. Challenge testing of smoked fish showed growth of L. monocytogenes in 12/25 samples stored for 3-4 weeks at 4 degrees C. Of 45 (non-inoculated) smoked fish samples (13 of which were initially positive in 25 g) which were subjected to shelf-life testing, numbers exceeded 100 CFU/g in only one sample

  1. Inactivation by lemon juice of Escherichia coli O157:H7, Salmonella Enteritidis, and Listeria monocytogenes in beef marinating for the ethnic food kelaguen.

    Science.gov (United States)

    Yang, Jian; Lee, Delores; Afaisen, Shayna; Gadi, Rama

    2013-01-01

    Lemon juice, a major source of acidulant citric acid, is frequently used in the preparation of ethnic foods. Raw or partially cooked meats are marinated with lemon juice in the preparation of a popular Chamorro dish called kelaguen, which is, unfortunately, strongly associated with foodborne illness outbreaks in Guam. We investigated the efficacy of lemon juice in reducing numbers of Escherichia coli O157:H7, Salmonella Enteritidis, and Listeria monocytogenes at stationary phase during marination. Beef inoculated with a three-strain mixture of E. coli O157:H7, S. Enteritidis, or L. monocytogenes at 10(6)CFU/mL was marinated with lemon juice from 0.2 to 10mL/g for 48h at 28°C. The decline of the pathogens during marination exhibited various degrees of deviation from first-order kinetics. Based on calculations with both linear regression and Weibull models, the decimal reduction time (4-D values) over the range of lemon concentrations was 366-5.1h for E. coli O157:H7, 282-2.4h for S. Enteritidis, and 104-2.4h for L. monocytogenes, indicating that E. coli O157:H7 was the most lemon-juice-resistant of the three. The pathogen reduction time (log 4-D values) plotted against undissociated titratable citric acid exhibited a biphasic pattern. The pathogen reduction time (log 4-D or δ values) was linearly correlated with the pH of the marinating beef (R(2)=0.92 to 0.98). The Z(pH) values (pH dependence of death rate) with beef marination were 1.03 for E. coli O157:H7, 0.92 for S. Enteritidis, and 1.29 for L. monocytogenes, indicating that L. monocytogenes was the most pH resistant of the three. L. monocytogenes exhibited less resistance to lemon juice than S. Enteritidis at pH of 3.5-4.4 but more resistance at pH of 2.6-2.8. In addition, at 4°C, all three pathogens exhibited 4-D values 1.7-4.1 times greater than those at 24°C at 5mL lemon juice/g beef. In conclusion, the usual beef marinating practice for kelaguen preparation (lemon juice/g beef for 1-12h) did not

  2. Effect of antimicrobial spice and herb extract combinations on Listeria monocytogenes, Staphylococcus aureus, and spoilage microflora growth on cooked ready-to-eat vacuum-packaged shrimp.

    Science.gov (United States)

    Weerakkody, Nimsha S; Caffin, Nola; Dykes, Gary A; Turner, Mark S

    2011-07-01

    Two spice and herb extract combinations from galangal (Alpinia galanga), rosemary (Rosmarinus officinalis), and lemon iron bark (Eucalyptus staigerana) were evaluated for their ability to inhibit the growth of inoculated Listeria monocytogenes and Staphylococcus aureus and naturally present spoilage microflora on cooked ready-to-eat shrimp stored for 16 days at 4 or 8 °C. A combination of galangal, rosemary, and lemon iron bark significantly reduced (P galangal and rosemary extract significantly reduced (P galangal, rosemary, and lemon iron bark extracts can be used to control the growth of spoilage microflora on ready-to-eat shrimp.

  3. Stimulation of the faecal excretion of 2,4,5,2',4',5'-hexachlorobiphenyl in rats by squalane.

    Science.gov (United States)

    Richter, E; Schäfer, S G; Fichtl, B

    1983-06-01

    Faecal excretion of 2,4,5,2',4',5'-hexachlorobiphenyl (6-CB) was followed for 19 weeks in rats fed a control diet, or a squalane-supplemented diet, for up to 17 weeks. In 3 d after a single oral dose of 8 mg/kg of 6-CB, 20% dose was excreted in faeces as unchanged 6-CB, which probably represents that not-absorbed. From day 4 to 133 only an additional 2-4% dose was excreted in faeces by control animals. Addition of 8% squalane to the diet 2, 6 and 15 weeks after dosing resulted in a five-fold increase of daily 6-CB excretion in faeces independent of the time of beginning the treatment. Total excretion of 6-CB in faeces from day 4 to 133 was 3.6, 6-7 and 9.3% dose after 4, 13 and 17 weeks of squalane treatment, respectively. No adverse effects of long-term squalane treatment on body-weight gain, feed efficiency and organ weights were observed. Plasma cholesterol and triglycerides were significantly lowered. Independent of the duration of treatment, the livers of rats fed the squalane-supplemented diet contained 40-50 micrograms/g squalane. Within the limits of detection no squalane could be found in lungs, kidneys, abdominal fat, spleen and blood. It is concluded that 6-CB elimination can be enhanced by oral treatment with squalane even a long time after uptake of the poison. As there was no alteration in the tissue distribution of 6-CB, the 6-CB excreted after squalane treatment probably originates from all tissues.

  4. A Look inside the Listeria monocytogenes Biofilms Extracellular Matrix

    Directory of Open Access Journals (Sweden)

    Angelo Colagiorgi

    2016-07-01

    Full Text Available Listeria monocytogenes is a foodborne pathogen able to persist in food industry and is responsible for a severe illness called listeriosis. The ability of L. monocytogenes to persist in environments is due to its capacity to form biofilms that are a sessile community of microorganisms embedded in a self-produced matrix of extracellular polymeric substances (EPS’s. In this review, we summarized recent efforts performed in order to better characterize the polymeric substances that compose the extracellular matrix (ECM of L. monocytogenes biofilms. EPS extraction and analysis led to the identification of polysaccharides, proteins, extracellular DNA, and other molecules within the listerial ECM. All this knowledge will be useful for increasing food protection, suggesting effective strategies for the minimization of persistence of L. monocytogenes in food industry environments.

  5. FDA Bacteriological Analytical Manual, Chapter 10, 2003: Listeria monocytogenes

    Science.gov (United States)

    FDA Bacteriological Analytical Manual, Chapter 10 describes procedures for analysis of food samples and may be adapted for assessment of solid, particulate, aerosol, liquid and water samples containing Listeria monocytogenes.

  6. Growth inhibition of Listeria monocytogenes by a nonbacteriocinogenic Carnobacterium piscicola

    DEFF Research Database (Denmark)

    Nilsson, Lilian; Bech Hansen, T.; Garrido, P.

    2005-01-01

    Aims: This study elucidates the mechanisms by which a nonbacteriocinogenic Carnobacterium piscicola inhibits growth of Listeria monocytogenes. Methods and Results: Listeria monocytogenes was exposed to live cultures of a bacteriocin-negative variant of C. piscicola A9b in co-culture, in a diffusion...... chamber system, and to a cell-free supernatant. Suppression of maximum cell density (0-3.5 log units) of L. monocytogenes was proportional to initial levels of C. pisciola (10(3)-10(7) CFU ml(-1)). Cell-to-cell contact was not required to cause inhibition. The cell-free C. piscicola supernatant caused...... a decrease in L. monocytogenes maximum cell density, which was abolished by glucose addition but not by amino acid, vitamin or mineral addition. The fermentate also gave rise to a longer lag phase and a reduction in growth rate. These effects were independent of glucose and may have been caused by acetate...

  7. Pyelonephritis with bacteremia caused by Listeria monocytogenes: A case report.

    Science.gov (United States)

    Uno, Shunsuke; Hase, Ryota; Toguchi, Akihiro; Otsuka, Yoshihito; Hosokawa, Naoto

    2017-02-01

    Listeria monocytogenes is a well-known cause of meningitis, colitis, and bacteremia; however, obstructive pyelonephritis caused by L. monocytogenes has never been reported. We herein report on a 90-year-old Japanese woman with obstructive pyelonephritis and bacteremia due to uterus carcinoma invading the ureter. She was admitted to our hospital complaining of fever and chills, and her physical examination revealed left costovertebral angle tenderness. Computed tomography showed hydronephrosis and complete ureteral obstruction due to tumor invasion. Blood and urine cultures upon nephrostomy revealed the growth of L. monocytogenes. We treated the patient with two weeks of intravenous ampicillin and an additional one-week treatment of oral sulfamethoxazole/trimethoprim. This case shows the importance to recognize L. monocytogenes as a potential causative agent of urinary tract infection. Copyright © 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  8. Conditions Affecting Shelf-Life of Inoculated Legume Seed

    OpenAIRE

    Greg Gemell; Elizabeth Hartley; Rosalind Deaker

    2012-01-01

    Microbial inoculants are becoming more available as sustainable alternatives to fertilizers and other agrichemicals in broad-acre cropping. However, with the exception of legume inoculants little is understood about effective delivery and survival of the inoculum. Legume inoculants are applied to both seed and soil but seed inoculation is the most economical technique. Large quantities of pasture seed in Australia are inoculated by commercial seed coating companies, but the long-term survival...

  9. Reduction of 4(5)-Methylimidazole Using Cookie Model Systems.

    Science.gov (United States)

    Jung, Min-Chul; Kim, Mina K; Lee, Kwang-Geun

    2017-09-11

    The objective of this study was to determine the reduction of 4(5)-methylimidazole (4-MI) under various baking conditions. For 4-MI analysis, an analytical method using gas chromatography-mass spectrometry was developed. The developed method was validated with linearity (r(2) > 0.999), recovery (101% to 103%, 3 levels), and precision (1.5% to 4.3%, 3 levels). Limits of detection and quantification were 18.5 and 56.0 μg/kg, respectively. This method was used to monitor the level of 4-MI in 11 commercial cookies, which ranged from 71.5 to 1254.8 μg/kg. Time and temperature were modified in the cookie model system to reduce 4-MI. The largest reduction in 4-MI (56%) was achieved by baking at 140 °C for 8 min; however the cookies baked at this condition were not well accepted by consumers. With combination of consumer liking test result, baking cookies at 140 °C for 16 min is optimal for 4-MI reduction (28% reduction), while it has minimal impact on consumer acceptance. A strong correlation (r(2) = 0.9981) was found between caramel colorant and 4-MI in the cookie model system. © 2017 Institute of Food Technologists®.

  10. Caratterizzazione biomolecolare di listeria monocytogenes in suini regolarmente macellati

    OpenAIRE

    Santoro, Cristina

    2009-01-01

    Listeria monocytogenes è un batterio patogeno responsabile di una malattia potenzialmente molto grave per l’uomo. L’infezione avviene soprattutto tramite l’ingestione di alimenti di origine animale contaminati, e può propagarsi per via transplacentare al feto. Il potenziale patogeno di L. monocytogenes è dovuto soprattutto a caratteristici fattori di virulenza con i quali alcuni ceppi sono in grado di attaccare la cellula dell’organismo ospite potendo aderire, invadere, moltiplicare e prop...

  11. Comparison of artificial inoculation methods for studying ...

    African Journals Online (AJOL)

    divya

    2013-05-01

    May 1, 2013 ... Establishment of disease by artificial inoculation is essential for studies of various aspects of plant pathology. Keeping this in mind .... three to four days under cool white fluorescent light (2,000 lux) followed by 2 days ... and placed in growth chambers at 25°C and 70% relative humidity. The Petri plates were ...

  12. Coping With Pain: Studies in Stress Inoculation.

    Science.gov (United States)

    Horan, John J.; And Others

    The stress-inoculation paradigm for helping clients deal with pain consists of education about the psychological dimensions of pain, training in a number of coping skills relevant to each dimension, and practice in applying these skills to the noxious stimulus. Presented are two studies, the first of which represents a component analysis of stress…

  13. Isolation and Identification of Listeria monocytogenes from Retail

    Directory of Open Access Journals (Sweden)

    A.D.I. Alsheikh

    2013-02-01

    Full Text Available Listeria species are widely distributed in environment and L. monocytogenes are the causal agent of Listeriosis, the disease that can be serious and fatal to human and animals. The objectives of this study were to detect, isolate and identify Listeria monocytogenes from retail broiler chicken ready to eat meat products in restaurants-Khartoum state, Sudan. A total of 250 retail broiler chicken ready to eat meat products were collected from restaurants in Khartoum State, 50 sample from frozen chicken burger, 50 sample from frozen chicken sausages, 50 sample from frozen chicken meat balls (kofta, 50 sample from chicken shawerma and 50 sample from chicken mortedella, Listeria spp. were isolated by the conventional International Organization for Standardization method and L. monocytogenes identified by biochemical test. The results showed that out of total 250 samples, 95 (38% were found to be contaminated with Listeria spp. the isolation rate was as follows: L. monocytogenes (13.6%, L. ivanovi (20.8%, L. grayi (1.6%, L. seeligeri (0.8% and L. welshimeri (1.2%. The results presented in this study indicate the contamination of retail broiler chicken ready to eat meat products with L. monocytogenes. This study reported the occurrence and distribution of L. monocytogenes and other Listeria species in retail meat products (frozen chicken burger, frozen chicken sausages, frozen chicken meat balls (kofta, chicken shawerma and chicken mortedella, purchased from restaurants in Khartoum state Sudan.

  14. Listeria monocytogenes does not survive ingestion by Acanthamoeba polyphaga.

    Science.gov (United States)

    Akya, Alisha; Pointon, Andrew; Thomas, Connor

    2010-03-01

    Listeria monocytogenes is a ubiquitous bacterium capable of infecting humans, particularly pregnant women and immunocompromised individuals. Although the intracellular invasion and pathogenesis of listeriosis in mammalian tissues has been well studied, little is known about the ecology of L. monocytogenes , and in particular the environmental reservoir for this bacterium has not been identified. This study used short-term co-culture at 15, 22 and 37 degrees C to examine the interaction of L. monocytogenes strains with Acanthamoeba polyphaga ACO12. Survival of L. monocytogenes cells phagocytosed by monolayers of trophozoites was assessed by culture techniques and microscopy. A. polyphaga trophozoites eliminated bacterial cells within a few hours post-phagocytosis, irrespective of the incubation temperature used. Wild-type L. monocytogenes and a phenotypic listeriolysin O mutant were unable to either multiply or survive within trophozoites. By contrast, Salmonella enterica serovar Typhimurium C5 cells used as controls were able to survive and multiply within A. polyphaga trophozoites. The data presented indicate that A. polyphaga ACO12 is unlikely to harbour L. monocytogenes, or act as an environmental reservoir for this bacterium.

  15. Listeria monocytogenes, a down-to-earth pathogen.

    Science.gov (United States)

    Vivant, Anne-Laure; Garmyn, Dominique; Piveteau, Pascal

    2013-01-01

    Listeria monocytogenes is the causative agent of the food-borne life threatening disease listeriosis. This pathogenic bacterium received much attention in the endeavor of deciphering the cellular mechanisms that underlie the onset of infection and its ability to adapt to the food processing environment. Although information is available on the presence of L. monocytogenes in many environmental niches including soil, water, plants, foodstuff and animals, understanding the ecology of L. monocytogenes in outdoor environments has received less attention. Soil is an environmental niche of pivotal importance in the transmission of this bacterium to plants and animals. Soil composition, microbial communities and macrofauna are extrinsic edaphic factors that direct the fate of L. monocytogenes in the soil environment. Moreover, farming practices may further affect its incidence. The genome of L. monocytogenes presents an extensive repertoire of genes encoding transport proteins and regulators, a characteristic of the genome of ubiquitous bacteria. Postgenomic analyses bring new insights in the process of soil adaptation. In the present paper focussing on soil, we review these extrinsic and intrinsic factors that drive environmental adaptation of L. monocytogenes.

  16. Inhibition of sortase A by chalcone prevents Listeria monocytogenes infection.

    Science.gov (United States)

    Li, Hongen; Chen, Yutao; Zhang, Bing; Niu, Xiaodi; Song, Meng; Luo, Zhaoqing; Lu, Gejin; Liu, Bowen; Zhao, Xiaoran; Wang, Jianfeng; Deng, Xuming

    2016-04-15

    The critical role of sortase A in gram-positive bacterial pathogenicity makes this protein a good potential target for antimicrobial therapy. In this study, we report for the first time the crystal structure of Listeria monocytogenes sortase A and identify the active sites that mediate its transpeptidase activity. We also used a sortase A (SrtA) enzyme activity inhibition assay, simulation, and isothermal titration calorimetry analysis to discover that chalcone, an agent with little anti-L. monocytogenes activity, could significantly inhibit sortase A activity with an IC50 of 28.41 ± 5.34 μM by occupying the active site of SrtA. The addition of chalcone to a co-culture of L. monocytogenes and Caco-2 cells significantly inhibited bacterial entry into the cells and L. monocytogenes-mediated cytotoxicity. Additionally, chalcone treatment decreased the mortality of infected mice, the bacterial burden in target organs, and the pathological damage to L. monocytogenes-infected mice. In conclusion, these findings suggest that chalcone is a promising candidate for the development of treatment against L. monocytogenes infection.

  17. Evolutionary dynamics of the accessory genome of Listeria monocytogenes.

    Directory of Open Access Journals (Sweden)

    Henk C den Bakker

    Full Text Available Listeria monocytogenes, a foodborne bacterial pathogen, is comprised of four phylogenetic lineages that vary with regard to their serotypes and distribution among sources. In order to characterize lineage-specific genomic diversity within L. monocytogenes, we sequenced the genomes of eight strains from several lineages and serotypes, and characterized the accessory genome, which was hypothesized to contribute to phenotypic differences across lineages. The eight L. monocytogenes genomes sequenced range in size from 2.85-3.14 Mb, encode 2,822-3,187 genes, and include the first publicly available sequenced representatives of serotypes 1/2c, 3a and 4c. Mapping of the distribution of accessory genes revealed two distinct regions of the L. monocytogenes chromosome: an accessory-rich region in the first 65° adjacent to the origin of replication and a more stable region in the remaining 295°. This pattern of genome organization is distinct from that of related bacteria Staphylococcus aureus and Bacillus cereus. The accessory genome of all lineages is enriched for cell surface-related genes and phosphotransferase systems, and transcriptional regulators, highlighting the selective pressures faced by contemporary strains from their hosts, other microbes, and their environment. Phylogenetic analysis of O-antigen genes and gene clusters predicts that serotype 4 was ancestral in L. monocytogenes and serotype 1/2 associated gene clusters were putatively introduced through horizontal gene transfer in the ancestral population of L. monocytogenes lineage I and II.

  18. Listeria monocytogenes a pathogen down-to-earth

    Directory of Open Access Journals (Sweden)

    Anne-Laure eVivant

    2013-11-01

    Full Text Available Listeria monocytogenes is the causative agent of the food-borne life threatening disease listeriosis. This pathogenic bacterium received much attention in the endeavour of deciphering the cellular mechanisms that underlie the onset of infection and its ability to adapt to the food processing environment. Although information is available on the presence of L. monocytogenes in many environmental niches including soil, water, plants, foodstuff and animals, understanding the ecology of L. monocytogenes in outdoor environments has received less attention. Soil is an environmental niche of pivotal importance in the transmission of this bacterium to plants and animals. Soil composition, microbial communities and macrofauna are extrinsic edaphic factors that direct the fate of L. monocytogenes in the soil environment. Moreover, farming practices may further affect its incidence. The genome of L. monocytogenes presents an extensive repertoire of genes encoding transport proteins and regulators, a characteristic of the genome of ubiquitous bacteria. Postgenomic analyses bring new insights in the process of soil adaptation. In the present paper focussing on soil, we review these extrinsic and intrinsic factors that drive environmental adaptation of L. monocytogenes.

  19. Short communication: Inhibitory activities of the lantibiotic nisin combined with phenolic compounds against Staphylococcus aureus and Listeria monocytogenes in cow milk.

    Science.gov (United States)

    Alves, Fernanda C B; Barbosa, Lidiane N; Andrade, Bruna F M T; Albano, Mariana; Furtado, Fabiana Barcelos; Marques Pereira, Ana Flávia; Rall, Vera L M; Fernandes Júnior, Ary

    2016-03-01

    We aimed to investigate the antibacterial activities of carvacrol, thymol, eugenol, cinnamaldehyde, and lantibiotic nisin against standard bacterial strains of the milk pathogens Staphylococcus aureus ATCC 25923 and Listeria monocytogenes ATCC 15313 in cow milk. The minimum inhibitory concentrations (MIC) of these substances were recorded. The synergistic effects were also assessed in culture medium (time kill curve) and in a food model (cow milk) during the storage period (4 °C for 6 d) after inoculation with S. aureus and L. monocytogenes individually by combining nisin and the phenolic compounds at proportions of 1/4 + 1/4 the MIC (determined in a previous in vitro assay) in the culture medium and 1/4 + 1/4 of MIC in the food model. Inhibitory activities of nisin and the tested compounds, as well as synergism in the combinations, were found against both bacteria assayed. Bacteriostatic effects were found with all combinations and a significant difference in L. monocytogenes reduction was found compared with the control assays. Thus, the antibacterial activity of nisin combined with phenolic compounds was confirmed against these pathogenic bacteria that are important in the milk industry, or more broadly in food science, with potential applications for milk preservation.

  20. Inhibition of Escherichia coli O157:H7, Listeria monocytogenes and Staphylococcus aureus on sliced roast beef by cetylpyridinium chloride and acidified sodium chlorite.

    Science.gov (United States)

    Lim, Kyungwha; Mustapha, Azlin

    2007-02-01

    The effects of 0.5% cetylpyridinium chloride (CPC), 0.12% acidified sodium chlorite (ASC) and a mix of equal volume of the two (0.25% CPC-0.06% ASC) on Escherichia coli O157:H7, Listeria monocytogenes and Staphylococcus aureus were evaluated on inoculated sliced roast beef. The antimicrobial agents were, respectively, sprayed on the beef surfaces and tray absorbent pads, and samples were stored at 4 degrees C for 10 days (d). At 0 d, L. monocytogenes and S. aureus were reduced to undetectable levels in 2 h after spraying with CPC. CPC-ASC treatment reduced E. coli O157:H7, L. monocytogenes and S. aureus by 4.07, 6.37 and 4.32 log cfu/cm2, respectively, at 0 d. ASC treatment reduced the population of E. coli O157:H7 by 6.09 log cfu/cm2 at 10 d. CPC treatment caused a slight discoloration and ASC-treated beef surfaces demonstrated the lowest redness and highest lightness. The grey colour and off-odour were significant in the ASC-treated beef samples, while CPC-treated samples demonstrated less off-odor and brown colour from 0 to 4 d. Based on our results, it appears that the application of CPC on sliced roast beef can extend the shelf-life of the product without impairing its quality.

  1. Risk-based control of food-borne pathogens Listeria monocytogenes and Salmonella enterica in the Italian fermented sausages Cacciatore and Felino.

    Science.gov (United States)

    Mataragas, M; Bellio, A; Rovetto, F; Astegiano, S; Decastelli, L; Cocolin, L

    2015-05-01

    Fermentation is the most important killing step during production of fermented meats to eliminate food-borne pathogens. The objective was to evaluate whether the food-borne pathogens Listeria monocytogenes and Salmonella enterica may survive during the production of two Italian fermented sausages. Sausage batter was inoculated with five strains of L. monocytogenes or S. enterica (ca. 10(5)-10(6) cfu/g) and their kinetic behavior was monitored during production. Both pathogens survived relatively well (in Cacciatore L. monocytogenes and S. enterica inactivation was ca. 0.38±0.23 and 1.10±0.24 log cfu/g, respectively; in Felino was ca. 0.39±0.25 and 1.62±0.38 log cfu/g, respectively) due to the conditions prevailing during production (slow dehydration rate, small reduction of water activity and fermentation temperature mainly below 20 °C during the first 48 h of fermentation). Quantitative analysis of data originating from challenge tests provide critical information on which combinations of the process parameters would potentially lead to better control of the pathogens.

  2. Prevalence of Listeria species in camel sausages from retail markets in Aydin province in Turkey and RAPD analysis of Listeria monocytogenes Isolates

    Directory of Open Access Journals (Sweden)

    Ozbey Gokben

    2006-06-01

    Full Text Available Abstract Samples were taken from 100 camel sausages from the different retail markets in Aydin province in the south-west of Turkey and they were tested for the presence of Listeria spp by biochemical methods. Samples were enriched using Listeria Enrichment Broth and they were inoculated onto Listeria Selective Agar. Listeria monocytogenes was isolated from nine samples (9%, Listeria innocua from 14 samples (14% and Listeria welshimeri from two samples(2%. A 701 bp fragment of listeriolysin O sequence for L. monocytogenes was amplified using specific primers by polymerase chain reaction (PCR for confirmation of the identification. A random primer (OPA-11 was used in a random amplified polymorphic DNA (RAPD assay. This detected five different band profiles amongst the L. monocytogenes isolates, indicating a relatively large amount of genetic heterogeneity amongst the nine isolates. The study has highlighted the need for improved strategies for food safety, in particular appropriate hygienic precautions to avoid contamination of sausage during the manufacturing process and appropriate preservation techniques during storage and transport, to prevent transmission of Listeria spp to consumers at home and abroad.

  3. Upstream sample processing facilitates PCR detection of Listeria monocytogenes in mayonnaise-based ready-to-eat (RTE) salads.

    Science.gov (United States)

    Isonhood, Jamie; Drake, MaryAnne; Jaykus, Lee-Ann

    2006-09-01

    Sample pretreatment to reduce volume and concentrate cells of the target organism(s) prior to molecular detection offers a useful supplement or alternative to cultural enrichment. The purpose of this study was to develop an upstream processing method to facilitate the detection of Listeria monocytogenes in ready-to-eat (RTE) salads by PCR. Potato salad, a model RTE commodity, was seeded with L. monocytogenes and processed by two alternative upstream sample processing methods (designated one-step and two-step centrifugation), followed by DNA extraction, PCR amplification, and Southern hybridization. The two-step method resulted in 1,000-fold improvements in the PCR detection limit, from 10(6) Cfu/g (no sample processing) to 10(3) Cfu/g. The two-step method was applied for upstream sample processing of four representative deli salad items artificially inoculated with L. monocytogenes at levels ranging from 10(1)-10(6) Cfu/g. Following DNA extraction, PCR amplification, and Southern hybridization, detection was achieved at input levels of 10(5) Cfu/g for chicken salad, 10(4) Cfu/g for macaroni salad, and 10(3) Cfu/g for potato and seafood salads. The two-step method reported here facilitates the production of a final sample concentrate of reduced volume and improved purity which was compatible with PCR amplification. This approach offers further progress in our efforts to reduce or eliminate cultural enrichment in an effort to speed time to results when applying molecular methods to the detection of pathogens in foods.

  4. Ca(2+) induces PI(4,5)P2 clusters on lipid bilayers at physiological PI(4,5)P2 and Ca(2+) concentrations.

    Science.gov (United States)

    Sarmento, Maria J; Coutinho, Ana; Fedorov, Aleksander; Prieto, Manuel; Fernandes, Fabio

    2014-03-01

    Calcium has been shown to induce clustering of PI(4,5)P2 at high and non-physiological concentrations of both the divalent ion and the phosphatidylinositol, or on supported lipid monolayers. In lipid bilayers at physiological conditions, clusters are not detected through microscopic techniques. Here, we aimed to determine through spectroscopic methodologies if calcium plays a role in PI(4,5)P2 lateral distribution on lipid bilayers under physiological conditions. Using several different approaches which included information on fluorescence quantum yield, polarization, spectra and diffusion properties of a fluorescent derivative of PI(4,5)P2 (TopFluor(TF)-PI(4,5)P2), we show that Ca(2+) promotes PI(4,5)P2 clustering in lipid bilayers at physiological concentrations of both Ca(2+) and PI(4,5)P2. Fluorescence depolarization data of TF-PI(4,5)P2 in the presence of calcium suggests that under physiological concentrations of PI(4,5)P2 and calcium, the average cluster size comprises ~15 PI(4,5)P2 molecules. The presence of Ca(2+)-induced PI(4,5)P2 clusters is supported by FCS data. Additionally, calcium mediated PI(4,5)P2 clustering was more pronounced in liquid ordered (lo) membranes, and the PI(4,5)P2-Ca(2+) clusters presented an increased affinity for lo domains. In this way, PI(4,5)P2 could function as a lipid calcium sensor and the increased efficiency of calcium-mediated PI(4,5)P2 clustering on lo domains might provide targeted nucleation sites for PI(4,5)P2 clusters upon calcium stimulus.

  5. Effects of gamma and electron beam irradiation on the survival of pathogens inoculated into sliced and pizza cheeses

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun-Joo [Department of Food Science and Technology, Chung-Ang University, Ansung, Gyunggi-do 456-756 (Korea, Republic of); Ham, Jun-Sang [Animal Products Processing Division, National Livestock Research Institute, RDA, Suwon 441-706 (Korea, Republic of); Lee, Ju-Woon [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Kim, Keehyuk [Department of Culinary Nutrition, Woosong University, Daejeon 300-718 (Korea, Republic of); Ha, Sang-Do [Department of Food Science and Technology, Chung-Ang University, Ansung, Gyunggi-do 456-756 (Korea, Republic of); Jo, Cheorun, E-mail: cheorun@cnu.ac.k [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2010-06-15

    The objective of this study was to identify the efficacy of gamma and electron beam irradiation of the food-borne pathogens (Listeria monocytogenes and Staphylococcus aureus) in sliced and pizza cheeses commercially available in the Korean market. Total aerobic bacteria and yeast/mold in the cheeses ranged from 10{sup 2} to 10{sup 3} Log CFU/g. Irradiation of 1 kGy for sliced cheese and 3 kGy for pizza cheese were sufficient to lower the total aerobic bacteria to undetectable levels (10{sup 1} CFU/g). Pathogen inoculation test revealed that gamma irradiation was more effective than electron beam irradiation at the same absorbed dose, and the ranges of the D{sub 10} values were from 0.84 to 0.93 kGy for L. monocytogenes and from 0.60 to 0.63 kGy for S. aureus. Results suggest that a low dose irradiation can improve significantly the microbial quality and reduce the risk of contamination of sliced and pizza cheeses by the food-borne pathogens which can potentially occur during processing.

  6. Effects of gamma and electron beam irradiation on the survival of pathogens inoculated into sliced and pizza cheeses

    Science.gov (United States)

    Kim, Hyun-Joo; Ham, Jun-Sang; Lee, Ju-Woon; Kim, Keehyuk; Ha, Sang-Do; Jo, Cheorun

    2010-06-01

    The objective of this study was to identify the efficacy of gamma and electron beam irradiation of the food-borne pathogens ( Listeria monocytogenes and Staphylococcus aureus) in sliced and pizza cheeses commercially available in the Korean market. Total aerobic bacteria and yeast/mold in the cheeses ranged from 10 2 to 10 3 Log CFU/g. Irradiation of 1 kGy for sliced cheese and 3 kGy for pizza cheese were sufficient to lower the total aerobic bacteria to undetectable levels (10 1 CFU/g). Pathogen inoculation test revealed that gamma irradiation was more effective than electron beam irradiation at the same absorbed dose, and the ranges of the D 10 values were from 0.84 to 0.93 kGy for L. monocytogenes and from 0.60 to 0.63 kGy for S. aureus. Results suggest that a low dose irradiation can improve significantly the microbial quality and reduce the risk of contamination of sliced and pizza cheeses by the food-borne pathogens which can potentially occur during processing.

  7. Synthesis and characterization of new 3-(4,5-dihydro-5-arylisoxazol-3-yl-4-hydroxyquinolin-2(1H-ones and 3-(4-styrylisoxazolo[4,5-c]quinolin-4(5H-one derivatives

    Directory of Open Access Journals (Sweden)

    S. Sarveswari

    2016-09-01

    Full Text Available The 4-hydroxy-3-(3-arylacryloylquinolin-2(1H-ones were synthesized from 3-acetyl-4-hydroxyquinolin-2(1H-one by microwave assisted synthesis, which in turn converted into their corresponding 3-(4,5-dihydro-5-arylisoxazol-3-yl-4-hydroxyquinolin-2(1H-ones and 3-(4-styrylisoxazolo[4,5-c]quinolin-4(5H-one derivatives.

  8. Behaviour of co-inoculated pathogenic and spoilage bacteria on poultry following several decontamination treatments.

    Science.gov (United States)

    Alonso-Hernando, Alicia; Capita, Rosa; Alonso-Calleja, Carlos

    2012-10-01

    The potential of chemical decontaminants to cause harmful effects on human health is among the causes of the rejection of antimicrobial treatments for removing surface contamination from poultry carcasses in the European Union. This study was undertaken to determine whether decontaminants might give a competitive advantage to pathogenic bacteria on poultry and involve a potential risk to consumer. A total of 144 chicken legs were co-inoculated with similar concentrations of pathogenic bacteria (Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica serotype Enteritidis or Escherichia coli) and spoilage bacteria (Brochothrix thermosphacta or Pseudomonas fluorescens). Samples were dipped for 15min in solutions (w/v) of trisodium phosphate (12%; TSP), acidified sodium chlorite (1200ppm; ASC), citric acid (2%; CA), peroxyacids (220ppm; PA) or chlorine dioxide (50ppm; CD), or were left untreated (control). Microbiological analyses were carried out on day 0 and every 24h until day 7 of storage (at 10±1°C). The modified Gompertz equation was used as the primary model to fit observed data. TSP, ASC and CA were effective in extending the lag phase (L, ranging from 1.47±1.34days to 4.06±1.16days) and in decreasing the concentration of bacteria during the stationary phase (D, ranging from 2.46±0.51 log(10) cfu/cm(2) to 8.64±0.53 log(10) cfu/cm(2)), relative to the control samples (L values ranging from 0.59±0.38days and 2.52±2.28days, and D values ranging from 6.32±0.89 log(10) cfu/cm(2) to 9.39±0.39 log(10) cfu/cm(2), respectively). Both on untreated and on most decontaminated samples the overgrowth of spoilage bacteria among the species tested was observed throughout storage, suggesting that spoilage would occur prior to any noteworthy increase in the levels of pathogenic microorganisms. However, L. monocytogenes counts similar to, or higher than, those for spoilage bacteria were observed on samples treated with TSP, ASC or CA, suggesting that these

  9. Inoculation Stress Hypothesis of Environmental Enrichment

    Science.gov (United States)

    Crofton, Elizabeth J.; Zhang, Yafang; Green, Thomas A.

    2014-01-01

    One hallmark of psychiatric conditions is the vast continuum of individual differences in susceptibility vs. resilience resulting from the interaction of genetic and environmental factors. The environmental enrichment paradigm is an animal model that is useful for studying a range of psychiatric conditions, including protective phenotypes in addiction and depression models. The major question is how environmental enrichment, a non-drug and non-surgical manipulation, can produce such robust individual differences in such a wide range of behaviors. This paper draws from a variety of published sources to outline a coherent hypothesis of inoculation stress as a factor producing the protective enrichment phenotypes. The basic tenet suggests that chronic mild stress from living in a complex environment and interacting non-aggressively with conspecifics can inoculate enriched rats against subsequent stressors and/or drugs of abuse. This paper reviews the enrichment phenotypes, mulls the fundamental nature of environmental enrichment vs. isolation, discusses the most appropriate control for environmental enrichment, and challenges the idea that cortisol/corticosterone equals stress. The intent of the inoculation stress hypothesis of environmental enrichment is to provide a scaffold with which to build testable hypotheses for the elucidation of the molecular mechanisms underlying these protective phenotypes and thus provide new therapeutic targets to treat psychiatric/neurological conditions. PMID:25449533

  10. Effect of Grapefruit Seed Extract on Thermal Inactivation of Listeria monocytogenes during Sous-Vide Processing of Two Marinated Mexican Meat Entrées.

    Science.gov (United States)

    Valenzuela-Melendres, Martin; Peña-Ramos, E Aida; Juneja, Vijay K; Camou, Juan Pedro; Cumplido-Barbeitia, German

    2016-07-01

    D- and z-values for Listeria monocytogenes were obtained for two Mexican meat entrées: pork meat marinated in tomatillo (green tomato) sauce (PTS) and beef marinated in a red chili sauce (BRCS), with addition of 0, 200, and 800 ppm of grapefruit seed extract (GSE). Meat samples inoculated with L. monocytogenes were packaged in sterile bags, immersed in a water bath, and held at 55, 57.5, 60, and 62.5°C for different periods of time. Depending upon the temperature, D-values at 0 ppm of GSE ranged from 26.19 to 2.03 min in BRCS and 26.41 to 0.8 min in PTS. Adding 800 ppm of GSE to BRCS thermally treated at 55 and 62.5°C significantly decreased inactivation time by 35%. A reduction in time of 25.9, 10.6, and 40.1% at 55, 57.5, and 60°C, respectively, was observed in PTS with 800 ppm of GSE. The z-values of L. monocytogenes were not significantly affected by GSE addition; average z-values were 7.25 and 5.09°C for BRCS and PTS, respectively. Estimated thermal lethality for a 7-D log reduction of L. monocytogenes under commercial-size sous-vide conditions at a reference temperature of 55°C was reached at 78 and 71 min for BRCS without and with 800 ppm of GSE, respectively. For PTS, 7-D reduction was attained at 69 and 61 min without and with addition of 800 ppm of GSE, respectively. Supplementing both Mexican meat entrées (BRCS and PTS) with 800 ppm of GSE rendered L. monocytogenes cells more sensitive to the lethal effect of heat. The results of this study will assist the retail food industry in designing acceptance limits on critical control points pertaining to cooking regimes to effectively eliminate L. monocytogenes in BRCS and PTS sous-vide processed Mexican meat entrées.

  11. Effect of high pressure, in combination with antilisterial agents, on the growth of Listeria monocytogenes during extended storage of cooked chicken.

    Science.gov (United States)

    Patterson, M F; Mackle, A; Linton, M

    2011-12-01

    A cocktail of Listeria monocytogenes strains was inoculated into cooked chicken (∼2.2 × 10³ CFU g⁻¹) which was then pressure-treated (600 MPa/2 min/20 °C) and stored for up to 105 days at 8 °C. In addition, sodium lactate (2% w/w) or a pressure-resistant Weissella viridescens strain, known to have antilisterial activity, were added to the meat prior to inoculation with the pathogen and pressure treatment, to investigate the effect on Listeria survival. Pressure treatment alone was not sufficient to eliminate all of the Listeria. Numbers of survivors were initially below the level of detection (50 CFU g⁻¹) but increased during storage to reach >10⁸ CFU g⁻¹ by day 21. The presence of W. viridescens significantly extended the lag phase of any Listeria that survived the initial pressure treatment by ∼35 days, but numbers then increased to reach ∼10⁷ CFU g⁻¹ by day 105. The addition of 2% sodium lactate in combination with pressure treatment was most effective at inhibiting the growth of L. monocytogenes and numbers remained below the limit of detection throughout the 105 day storage. The addition of antimicrobial agents, in combination with pressure, could be used to give additional food safety assurance without increasing pressure hold time.

  12. Effects of cetylpyridinium chloride, acidified sodium chlorite, and potassium sorbate on populations of Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus on fresh beef.

    Science.gov (United States)

    Lim, Kyungwha; Mustapha, Azlin

    2004-02-01

    The effects of selected food-grade antimicrobial agents at decreasing the number of pathogenic bacteria on fresh beef were determined. Beef cubes inoculated with Escherichia coli O157:H7, Listeria monocytogenes, or Staphylococcus aureus were sprayed with 0.5% cetylpyridinium chloride (CPC), 0.12% acidified sodium chlorite (ASC), 0.1% potassium sorbate (PS), or an equal mix of any two solutions. The beef samples were placed on absorbent tray pads sprayed with each single or mixed solution, wrapped with polyvinyl chloride film, heat sealed, and stored at 4 degrees C for 2 weeks. Surface sanitization using CPC, ASC, or an equal mix of these two agents effectively reduced microbial numbers on the beef during storage. At day 0, ASC and the CPC-ASC mix reduced the number of E. coli O157:H7 by 2.50 and 1.58 log CFU/cm2, respectively. CPC demonstrated a 3.25-log reduction of L. monocytogenes and a 4.70-log reduction of S. aureus at 14 days. The CPC-PS mix reduced E. coli O157:H7 numbers by 1.46, L. monocytogenes by 2.95, and S. aureus by 4.41 log CFU/cm2 at 14 days. PS alone and the mixed solutions, CPC-ASC, CPC-PS, or ASC-PS, were not as effective as ASC or CPC alone. To effectively reduce E. coli O157:H7, L. monocytogenes, or S. aureus numbers, higher (> 0.1%) concentrations of PS were necessary. Loss of redness and light color of beef surfaces consistently coincided with decreases in pH for ASC-treated beef samples.

  13. Phosphorylation of the rat Ins(1,4,5)P₃ receptor at T930 within the coupling domain decreases its affinity to Ins(1,4,5)P₃.

    Science.gov (United States)

    Haun, Shirley; Sun, Lu; Hubrack, Satanay; Yule, David; Machaca, Khaled

    2012-01-01

    The Ins(1,4,5)P 3 receptor acts as a central hub for Ca ( 2+) signaling by integrating multiple signaling modalities into Ca ( 2+) release from intracellular stores downstream of G-protein and tyrosine kinase-coupled receptor stimulation. As such, the Ins(1,4,5)P 3 receptor plays fundamental roles in cellular physiology. The regulation of the Ins(1,4,5)P 3 receptor is complex and involves protein-protein interactions, post-translational modifications, allosteric modulation, and regulation of its sub-cellular distribution. Phosphorylation has been implicated in the sensitization of Ins(1,4,5)P 3-dependent Ca ( 2+) release observed during oocyte maturation. Here we investigate the role of phosphorylation at T-930, a residue phosphorylated specifically during meiosis. We show that a phosphomimetic mutation at T-930 of the rat Ins(1,4,5)P 3 receptor results in decreased Ins(1,4,5)P 3-dependent Ca ( 2+) release and lowers the Ins(1,4,5)P 3 binding affinity of the receptor. These data, coupled to the sensitization of Ins(1,4,5)P 3-dependent Ca ( 2+) release during meiosis, argue that phosphorylation within the coupling domain of the Ins(1,4,5)P 3 receptor acts in a combinatorial fashion to regulate Ins(1,4,5)P 3 receptor function.

  14. FEASIBILITY STUDY OF BUSINESS IN AGARWOOD INOCULATION AT DIFFERENT STEM DIAMETERS AND INOCULATION PERIODS

    Directory of Open Access Journals (Sweden)

    Sri Suharti

    2011-12-01

    Full Text Available Indonesia signifies as the biggest agarwood producer country in the world. Its demand and price tend to increase and have brought about over exploitation of agarwood. Consequently, its population in nature has decreased significantly. To overcome the situation, since 1995, agarwood has been included in the CITES Appendix II. However, illegal exploitation remains persistent and reaches an excessive level. In order to deal with it, agarwood cultivation and its artificial production have been undertaken at several provinces in Indonesia. Some supporting factors for agarwood cultivation and artificial production are the availability of potential land for extensive cultivation, appropriate agro climate condition, simple cultivation technique and already being well adopted by farmers, the availability of necessary pathogen for agarwood inoculation, and the increasing demand with relatively high price. The research aims to analyze the feasibility study of agarwood inoculation business at several stem diameters (15 - 25 cm; 26 -35 cm and 36 - 40 cm and periods of inoculation (1 - 5 years. Data were collected through field observation and literature study. The results showed that inoculation on agarwood producer tree stands at 12.5% interest rate afforded positive net present value (NPV,  internal rate of return (IRR is much higher than market interest and benefit cost (B/C ratio >2 for those three diameter classes. Furthermore, if agarwood harvesting is delayed until five years after inoculation, NPV,  IRR and B/C ratio would be much higher. It can be concluded that inoculation on agarwood producer tree stands (at appropriate age for inoculation is feasible to be developed.

  15. Listeria monocytogenes in Fresh Produce: Outbreaks, Prevalence and Contamination Levels

    Directory of Open Access Journals (Sweden)

    Qi Zhu

    2017-03-01

    Full Text Available Listeria monocytogenes, a member of the genus Listeria, is widely distributed in agricultural environments, such as soil, manure and water. This organism is a recognized foodborne pathogenic bacterium that causes many diseases, from mild gastroenteritis to severe blood and/or central nervous system infections, as well as abortion in pregnant women. Generally, processed ready-to-eat and cold-stored meat and dairy products are considered high-risk foods for L. monocytogenes infections that cause human illness (listeriosis. However, recently, several listeriosis outbreaks have been linked to fresh produce contamination around the world. Additionally, many studies have detected L. monocytogenes in fresh produce samples and even in some minimally processed vegetables. Thus L. monocytogenes may contaminate fresh produce if present in the growing environment (soil and water. Prevention of biofilm formation is an important control measure to reduce the prevalence and survival of L. monocytogenes in growing environments and on fresh produce. This article specifically focuses on fresh produce–associated listeriosis outbreaks, prevalence in growing environments, contamination levels of fresh produce, and associated fresh produce safety challenges.

  16. Listeria monocytogenes in Fresh Produce: Outbreaks, Prevalence and Contamination Levels

    Science.gov (United States)

    Zhu, Qi; Gooneratne, Ravi; Hussain, Malik Altaf

    2017-01-01

    Listeria monocytogenes, a member of the genus Listeria, is widely distributed in agricultural environments, such as soil, manure and water. This organism is a recognized foodborne pathogenic bacterium that causes many diseases, from mild gastroenteritis to severe blood and/or central nervous system infections, as well as abortion in pregnant women. Generally, processed ready-to-eat and cold-stored meat and dairy products are considered high-risk foods for L. monocytogenes infections that cause human illness (listeriosis). However, recently, several listeriosis outbreaks have been linked to fresh produce contamination around the world. Additionally, many studies have detected L. monocytogenes in fresh produce samples and even in some minimally processed vegetables. Thus L. monocytogenes may contaminate fresh produce if present in the growing environment (soil and water). Prevention of biofilm formation is an important control measure to reduce the prevalence and survival of L. monocytogenes in growing environments and on fresh produce. This article specifically focuses on fresh produce–associated listeriosis outbreaks, prevalence in growing environments, contamination levels of fresh produce, and associated fresh produce safety challenges. PMID:28282938

  17. Review of Microbial Inoculation Agent Used in Composting

    Institute of Scientific and Technical Information of China (English)

    HUANG Yaxi; FENG Shuqing; XU Xiuhong; MAO Zhicheng; WANG Mingyue; LIU Yanfang; HUANG Yan

    2009-01-01

    Microbial inoculation agent has been widely used in waste disposal and waste recycling. In this paper, the principle of fermentation in the composting of agricultural waste and the impact of microbial inoculation agent on composting were reviewed.The research and the application of microbial inoculation agent were also introduced. Based on the trend of the research, the promising prospect of microbial inoculation agent was discussed.

  18. Accessing inoculation methods of maize and wheat with Azospirillum brasilense

    OpenAIRE

    FUKAMI,J.; M. A. Nogueira; ARAUJO, R. S.; Hungria, M.

    2016-01-01

    The utilization of inoculants containing Azospirillum is becoming more popular due to increasing reports of expressive gains in grain yields. However, incompatibility with pesticides used in seed treatments represents a main limitation for a successful inoculation. Therefore, in this study we searched for alternatives methods for seed inoculation of maize and wheat, aiming to avoid the direct contact of bacteria with pesticides. Different doses of inoculants containing Azospirillum brasilense...

  19. Accessing inoculation methods of maize and wheat with Azospirillum brasilense.

    Science.gov (United States)

    Fukami, Josiane; Nogueira, Marco Antonio; Araujo, Ricardo Silva; Hungria, Mariangela

    2016-03-01

    The utilization of inoculants containing Azospirillum is becoming more popular due to increasing reports of expressive gains in grain yields. However, incompatibility with pesticides used in seed treatments represents a main limitation for a successful inoculation. Therefore, in this study we searched for alternatives methods for seed inoculation of maize and wheat, aiming to avoid the direct contact of bacteria with pesticides. Different doses of inoculants containing Azospirillum brasilense were employed to perform inoculation in-furrow, via soil spray at sowing and via leaf spray after seedlings had emerged, in comparison to seed inoculation. Experiments were conducted first under greenhouse controlled conditions and then confirmed in the field at different locations in Brazil. In the greenhouse, most parameters measured responded positively to the largest inoculant dose used in foliar sprays, but benefits could also be observed from both in-furrow and soil spray inoculation. However, our results present evidence that field inoculation with plant-growth promoting bacteria must consider inoculant doses, and point to the need of fine adjustments to avoid crossing the threshold of growth stimulation and inhibition. All inoculation techniques increased the abundance of diazotrophic bacteria in plant tissues, and foliar spray improved colonization of leaves, while soil inoculations favored root and rhizosphere colonization. In field experiments, inoculation with A. brasilense allowed for a 25 % reduction in the need for N fertilizers. Our results have identified alternative methods of inoculation that were as effective as the standard seed inoculation that may represent an important strategy to avoid the incompatibility between inoculant bacteria and pesticides employed for seed treatment.

  20. Total Synthesis of Two 4, 5-Dioxo-seco-eudesmane Sesquiterpenes

    Institute of Scientific and Technical Information of China (English)

    Li Jing FANG; Chen Xi ZHANG; Jin Chun CHEN; Guo Jun ZHENG; Yu Lin LI

    2005-01-01

    A facile synthetic route to two seco-eudesmane, 4, 5-dioxo-10-epi-4, 5-seco-γeudesmane (1) and 4, 5-dioxo-10-epi-4, 5-seco-γ-eudesmol (2) from (+)-dihydrocarvone has been described. Avoiding expensive reagents, this highly economic method especially suits for the synthesis of 4, 5-seco-eudesman-type and ophianon-type sesquiterpenes with a double bond at position 11 and 12.

  1. 7 CFR 201.24a - Inoculated seed.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Inoculated seed. 201.24a Section 201.24a Agriculture..., Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) FEDERAL SEED ACT FEDERAL SEED ACT REGULATIONS Labeling Agricultural Seeds § 201.24a Inoculated seed. Seed claimed to be inoculated shall...

  2. Listeria monocytogenes in renal transplant recipients Listeria monocytogenes em pacientes pós-transplante renal

    Directory of Open Access Journals (Sweden)

    Cristina Barroso HOFER

    1999-11-01

    Full Text Available Five cases of Listeria monocytogenes bacteriemia were observed from April to December 1985, among renal transplant recipients from the same hospital in São Paulo, Brazil. The patients were adults (mean age: 40.6 years, and the basic complain was fever, with no report of meningeal syndrome. Laboratory tests revealed the presence of two serovars, 1/2a and 4b, which were classified into three lysotypes. The four strains of serovar 4b showed the same antibiotype, with resistance to cefoxitin, clindamycin, oxacillin and penicillin.No período de abril a dezembro de 1985, foram observados cinco casos de listeriose em transplantados renais num mesmo hospital de São Paulo, SP. Os pacientes eram adultos (média de 40,6 anos tendo como queixa básica a febre. Laboratorialmente, em todos foram reconhecidos Listeria monocytogenes, caracterizada por dois sorovares 1/2a e 4b e três lisotipos distintos. As amostras do sorovar 4b apresentaram o mesmo antibiotipo: resistentes à cefoxitina, clindamicina, oxacilina e penicilina.

  3. Molecular determinants of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) binding to transient receptor potential V1 (TRPV1) channels.

    Science.gov (United States)

    Poblete, Horacio; Oyarzún, Ingrid; Olivero, Pablo; Comer, Jeffrey; Zuñiga, Matías; Sepulveda, Romina V; Báez-Nieto, David; González Leon, Carlos; González-Nilo, Fernando; Latorre, Ramón

    2015-01-23

    Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) has been recognized as an important activator of certain transient receptor potential (TRP) channels. More specifically, TRPV1 is a pain receptor activated by a wide range of stimuli. However, whether or not PI(4,5)P2 is a TRPV1 agonist remains open to debate. Utilizing a combined approach of mutagenesis and molecular modeling, we identified a PI(4,5)P2 binding site located between the TRP box and the S4-S5 linker. At this site, PI(4,5)P2 interacts with the amino acid residues Arg-575 and Arg-579 in the S4-S5 linker and with Lys-694 in the TRP box. We confirmed that PI(4,5)P2 behaves as a channel agonist and found that Arg-575, Arg-579, and Lys-694 mutations to alanine reduce PI(4,5)P2 binding affinity. Additionally, in silico mutations R575A, R579A, and K694A showed that the reduction in binding affinity results from the delocalization of PI(4,5)P2 in the binding pocket. Molecular dynamics simulations indicate that PI(4,5)P2 binding induces conformational rearrangements of the structure formed by S6 and the TRP domain, which cause an opening of the lower TRPV1 channel gate.

  4. Synthesis and muscarinic receptor pharmacology of a series of 4,5,6,7-tetrahydroisothiazolo[4,5-c]pyridine bioisosteres of arecoline

    DEFF Research Database (Denmark)

    Pedersen, H; Bräuner-Osborne, H; Ball, R G;

    1999-01-01

    A series of O- and ring-alkylated derivatives of 4,5,6,7-tetrahydroisothiazolo[4,5-c]pyridin-3-ol was synthesized via treatment of appropriately substituted 4-benzylamino-1,2,5,6-tetrahydropyridine-3-carboxamides with hydrogen sulfide and subsequent ring closure by oxidation with bromine. The mus......A series of O- and ring-alkylated derivatives of 4,5,6,7-tetrahydroisothiazolo[4,5-c]pyridin-3-ol was synthesized via treatment of appropriately substituted 4-benzylamino-1,2,5,6-tetrahydropyridine-3-carboxamides with hydrogen sulfide and subsequent ring closure by oxidation with bromine...

  5. Application of an active alginate coating to control the growth of Listeria monocytogenes on poached and deli turkey products.

    Science.gov (United States)

    Juck, Greg; Neetoo, Hudaa; Chen, Haiqiang

    2010-09-01

    The relatively high prevalence of Listeria monocytogenes in ready-to-eat (RTE) turkey products is of great concern. The overall objective of this study was to develop antimicrobial edible coating formulations to effectively control the growth of this pathogen. The antimicrobials studied were nisin (500IU/g), Novagard CB 1 (0.25%), Guardian NR100 (500ppm), sodium lactate (SL, 2.4%), sodium diacetate (SD, 0.25%), and potassium sorbate (PS, 0.3%). These were incorporated alone or in binary combinations into five edible coatings: alginate, kappa-carrageenan, pectin, xanthan gum, and starch. The coatings were applied onto the surface of home-style poached and processed deli turkey discs inoculated with ~3log CFU/g of L. monocytogenes. The turkey samples were then stored at 22 degrees C for 7days. For poached and processed deli turkey, the coatings were found to be equally effective, with pectin being slightly less effective than the others. The most effective poached turkey treatments seemed to be SL (2.4%)/SD (0.25%) and Nisin (500IU/g)/SL (2.4%), which yielded final populations of 3.0 and 4.9log CFU/g respectively compared to the control which was 7.9log CFU/g. For processed deli turkey, the most effective antimicrobial treatments seemed to be Nisin (500IU/g)/SD (0.25%) and Nisin (500IU/g)/SL (2.4%) with final populations of 1.5 and 1.7log CFU/g respectively compared to the control which was 6.5log CFU/g. In the second phase of the study, home-style poached and store-purchased roasted (deli) turkey inoculated with the pathogen at a level of ~3log CFU/g were coated with alginate incorporating selected antimicrobial combinations and stored for 8weeks at 4 degrees C. Alginate coatings supplemented with SL (2.4%)/PS (0.3%) delayed the growth of L. monocytogenes with final counts reaching 4.3log CFU/g (home-style poached turkey) and 6.5log CFU/g (roasted deli turkey) respectively while the counts in their untreated counterparts were significantly higher (P<0.05) reaching 9

  6. Listeria spp., y L. monocytogenes EN LECHE CRUDA DE CABRA

    Directory of Open Access Journals (Sweden)

    Yolanda Albarracín C

    2008-08-01

    Full Text Available Objective. To test non-pasteurized goat’s milk from the village of ‘la Garita’, Northern Santander, for Listeria monocytogenes. Material and methods. 90 samples of non-pasteurized goat’s milk were obtained over a 4 month period; pH and temperature of each sample were measured. The INVIMA technique was used to isolate L. monocytogenes; the species was confirmed by PCR. Results. The study showed that eight goat milk providers of the zone neither had refrigeration nor pasteurized the milk. The prevalence of L. monocytogenes was 3%; 15% of the samples had other species of Listeria. The milk obtained from this zone contained the pathogen that may cause listeriosis in children less than 5 years of age, pregnant women, adults and immunologically compromised patients. Conclusions. This study shows the occurrence of this pathogen in goat’s milk and identified areas of risk for those people who drink goat’s milk.

  7. Listeria monocytogenes response regulators important for stress tolerance and pathogenesis

    DEFF Research Database (Denmark)

    Kallipolitis, B H; Ingmer, H

    2001-01-01

    Environmental sensing by two-component signal transduction systems is likely to play a role for growth and survival of Listeria monocytogenes both during transmission in food products and within a host organism. Two-component systems typically consist of a membrane-associated sensor histidine...... kinase and a gene regulatory protein, the response regulator (RR). We have identified seven putative RR genes in L. monocytogenes LO28 by PCR using degenerate oligonucleotide primers. By insertional inactivation we obtained data suggesting that three of the putative RRs contribute to the pathogenicity...... of L. monocytogenes in mice. Strikingly, the mutants that were attenuated in virulence also had a decreased ability to grow in the presence of various stress conditions potentially encountered in an infection process. Thus, our data point to a connection between the ability of the putative two...

  8. Role of Extracellular DNA during Biofilm Formation by Listeria monocytogenes

    DEFF Research Database (Denmark)

    Harmsen, Morten; Lappann, Martin; Knøchel, S

    2010-01-01

    Listeria monocytogenes is a food-borne pathogen that is capable of living in harsh environments. It is believed to do this by forming biofilms, which are surface-associated multicellular structures encased in a self-produced matrix. In this paper we show that in L. monocytogenes extracellular DNA...... (eDNA) may be the only central component of the biofilm matrix and that it is necessary for both initial attachment and early biofilm formation for 41 L. monocytogenes strains that were tested. DNase I treatment resulted in dispersal of biofilms, not only in microtiter tray assays but also in flow...... cell biofilm assays. However, it was also demonstrated that in a culture without eDNA, neither Listeria genomic DNA nor salmon sperm DNA by itself could restore the capacity to adhere. A search for additional necessary components revealed that peptidoglycan (PG), specifically N-acetylglucosamine (NAG...

  9. Case of Contamination by Listeria Monocytogenes in Mozzarella Cheese

    Science.gov (United States)

    Tolli, Rita; Bossù, Teresa; Rodas, Eda Maria Flores; Di Giamberardino, Fabiola; Di Sirio, Alessandro; Vita, Silvia; De Angelis, Veronica; Bilei, Stefano; Sonnessa, Michele; Gattuso, Antonietta; Lanni, Luigi

    2014-01-01

    Following a Listeria monocytogenes detection in a mozzarella cheese sampled at a dairy plant in Lazio Region, further investigations have been conducted both by the competent Authority and the food business operatordairy factory (as a part of dairy factory HACCP control). In total, 90 dairy products, 7 brine and 64 environmental samples have been tested. The prevalence of Listeria monocytogenes was 24.4% in mozzarella cheese, and 9.4% in environmental samples, while brines were all negatives. Forty-seven strains of L. monocytogenes have been isolated, all belonging to 4b/4e serotype. In 12 of these, the macrorestriction profile has been determined by means of pulsed field gel electrophoresis. The profiles obtained with AscI enzyme showed a 100% similarity while those obtained with ApaI a 96.78% similarity. These characteristics of the isolated strains jointly with the production process of mozzarella cheese has allowed to hypothesise an environmental contamination. PMID:27800317

  10. Rhombencephalitis caused by Listeria monocytogenes in a pastured bull.

    Science.gov (United States)

    Matto, Carolina; Varela, Gustavo; Mota, María Inés; Gianneechini, Ruben; Rivero, Rodolfo

    2017-03-01

    A pastured 2-y-old cross-breed bull developed brainstem encephalitis (rhombencephalitis); Listeria monocytogenes was isolated from the brain. In the brainstem, there was perivascular cuffing, multiple microabscesses, and positive immunostaining for L. monocytogenes. Samples of bovine feces, water, feedstuffs, milking parlor soil, and bulk tank milk were collected from the dairy farm. Seven isolates of the genus Listeria were obtained, 6 of L. innocua and 1 of L. monocytogenes, which was found in the pasture where the bull grazed. Both isolates belonged to serotype 4b and were positive for internalins A, C, and J. According to the DNA fragment patterns of pulsed-field gel electrophoresis, the isolates were closely related. The source of infection was the pasture, implying that listeriosis should not be discounted in cases with compatible clinical signs but the absence of silage feeding.

  11. Keberadaan Bakteri Listeria monocytogenes pada Keju Gouda Produksi Lokal dan Impor (PRESENCE OF LISTERIA MONOCYTOGENES IN LOCAL AND IMPORTED GOUDA CHEESES)

    OpenAIRE

    Debby Fadhilah Pazra; Trioso Purnawarman; Denny Widaya Lukman

    2014-01-01

    Listeria monocytogenes is included in the foodborne pathogen, which has been associated with severaloutbreaks of human listeriosis especially in high risk groups. Listeria monocytogenes could be found inGouda cheeses because of poor hygienic and sanitation practices. In addition, this bacteria could surviveduring the making of cheese and cheese ripening process. The purpose of this study was to identify thepresence of L. monocytogenes in local and imported Gouda cheeses and how the safety lev...

  12. Diversity and distribution of Listeria monocytogenes in meat processing plants.

    Science.gov (United States)

    Martín, Belén; Perich, Adriana; Gómez, Diego; Yangüela, Javier; Rodríguez, Alicia; Garriga, Margarita; Aymerich, Teresa

    2014-12-01

    Listeria monocytogenes is a major concern for the meat processing industry because many listeriosis outbreaks have been linked to meat product consumption. The aim of this study was to elucidate L. monocytogenes diversity and distribution across different Spanish meat processing plants. L. monocytogenes isolates (N = 106) collected from food contact surfaces of meat processing plants and meat products were serotyped and then characterised by multilocus sequence typing (MLST). The isolates were serotyped as 1/2a (36.8%), 1/2c (34%), 1/2b (17.9%) and 4b (11.3%). MLST identified ST9 as the most predominant allelic profile (33% of isolates) followed by ST121 (16%), both of which were detected from several processing plants and meat products sampled in different years, suggesting that those STs are highly adapted to the meat processing environment. Food contact surfaces during processing were established as an important source of L. monocytogenes in meat products because the same STs were obtained in isolates recovered from surfaces and products. L. monocytogenes was recovered after cleaning and disinfection procedures in two processing plants, highlighting the importance of thorough cleaning and disinfection procedures. Epidemic clone (EC) marker ECI was identified in 8.5%, ECIII was identified in 2.8%, and ECV was identified in 7.5% of the 106 isolates. Furthermore, a selection of presumably unrelated ST9 isolates was analysed by multi-virulence-locus sequence typing (MVLST). Most ST9 isolates had the same virulence type (VT11), confirming the clonal origin of ST9 isolates; however, one ST9 isolate was assigned to a new VT (VT95). Consequently, MLST is a reliable tool for identification of contamination routes and niches in processing plants, and MVLST clearly differentiates EC strains, which both contribute to the improvement of L. monocytogenes control programs in the meat industry. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Analytical bioconjugates, aptamers, enable specific quantitative detection of Listeria monocytogenes.

    Science.gov (United States)

    Lee, Sang-Hee; Ahn, Ji-Young; Lee, Kyeong-Ah; Um, Hyun-Ju; Sekhon, Simranjeet Singh; Sun Park, Tae; Min, Jiho; Kim, Yang-Hoon

    2015-06-15

    As a major human pathogen in the Listeria genus, Listeria monocytogenes causes the bacterial disease listeriosis, which is a serious infection caused by eating food contaminated with the bacteria. We have developed an aptamer-based sandwich assay (ABSA) platform that demonstrates a promising potential for use in pathogen detection using aptamers as analytical bioconjugates. The whole-bacteria SELEX (WB-SELEX) strategy was adopted to generate aptamers with high affinity and specificity against live L. monocytogenes. Of the 35 aptamer candidates tested, LMCA2 and LMCA26 reacted to L. monocytogenes with high binding, and were consequently chosen as sensing probes. The ABSA platform can significantly enhance the sensitivity by employing a very specific aptamer pair for the sandwich complex. The ABSA platform exhibited a linear response over a wide concentration range of L. monocytogenes from 20 to 2×10(6) CFU per mL and was closely correlated with the following relationship: y=9533.3x+1542.3 (R(2)=0.99). Our proposed ABSA platform also provided excellent specificity for the tests to distinguish L. monocytogenes from other Listeria species and other bacterial genera (3 Listeria spp., 4 Salmonella spp., 2 Vibrio spp., 3 Escherichia coli and 3 Shigella spp.). Improvements in the sensitivity and specificity have not only facilitated the reliable detection of L. monocytogenes at extremely low concentrations, but also allowed for the development of a 96-well plate-based routine assay platform for multivalent diagnostics. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. The inoculation method affects colonization and performance of bacterial inoculant strains in the phytoremediation of soil contaminated with diesel oil.

    Science.gov (United States)

    Afzal, Muhammad; Yousaf, Sohail; Reichenauer, Thomas G; Sessitsch, Angela

    2012-01-01

    Plants in combination with microorganisms can remediate soils, which are contaminated with organic pollutants such as petroleum hydrocarbons. Inoculation of plants with degrading bacteria is one approach to improve remediation processes, but is often not successful due to the competition with resident microorganisms. It is therefore of high importance to address the persistence and colonization behavior of inoculant strains. The objective of this study was to determine whether the inoculation method (seed imbibement and soil inoculation) influences bacterial colonization, plant growth promotion and hydrocarbon degradation. Italian ryegrass was grown in non-sterilized soil polluted with diesel and inoculated with different alkane-degrading strains Pantoea sp. ITSI10, Pantoea sp. BTRH79 and Pseudomonas sp. MixRI75 individually as well as in combination. Inoculation generally had a beneficial effect on plant biomass production and hydrocarbon degradation, however, strains inoculated in soil performed better than applied by seed imbibement. Performance correlated with the colonization efficiency of the inoculated strains. The highest hydrocarbon degradation was observed in the treatment, in which all three strains were inoculated in combination into soil. Our study revealed that besides the degradation potential and competitive ability of inoculant strains the inoculation method plays an important role in determining the success of microbial inoculation.

  15. Ion channel regulation by phosphoinositides analyzed with VSPs-PI(4,5)P2 affinity, phosphoinositide selectivity, and PI(4,5)P2 pool accessibility.

    Science.gov (United States)

    Rjasanow, Alexandra; Leitner, Michael G; Thallmair, Veronika; Halaszovich, Christian R; Oliver, Dominik

    2015-01-01

    The activity of many proteins depends on the phosphoinositide (PI) content of the membrane. E.g., dynamic changes of the concentration of PI(4,5)P2 are cellular signals that regulate ion channels. The susceptibility of a channel to such dynamics depends on its affinity for PI(4,5)P2. Yet, measuring affinities for endogenous PIs has not been possible directly, but has relied largely on the response to soluble analogs, which may not quantitatively reflect binding to native lipids. Voltage-sensitive phosphatases (VSPs) turn over PI(4,5)P2 to PI(4)P when activated by depolarization. In combination with voltage-clamp electrophysiology VSPs are useful tools for rapid and reversible depletion of PI(4,5)P2. Because cellular PI(4,5)P2 is resynthesized rapidly, steady state PI(4,5)P2 changes with the degree of VSP activation and thus depends on membrane potential. Here we show that titration of endogenous PI(4,5)P2 with Ci-VSP allows for the quantification of relative PI(4,5)P2 affinities of ion channels. The sensitivity of inward rectifier and voltage-gated K(+) channels to Ci-VSP allowed for comparison of PI(4,5)P2 affinities within and across channel subfamilies and detected changes of affinity in mutant channels. The results also reveal that VSPs are useful only for PI effectors with high binding specificity among PI isoforms, because PI(4,5)P2 depletion occurs at constant overall PI level. Thus, Kir6.2, a channel activated by PI(4,5)P2 and PI(4)P was insensitive to VSP. Surprisingly, despite comparable PI(4,5)P2 affinity as determined by Ci-VSP, the Kv7 and Kir channel families strongly differed in their sensitivity to receptor-mediated depletion of PI(4,5)P2. While Kv7 members were highly sensitive to activation of PLC by Gq-coupled receptors, Kir channels were insensitive even when PI(4,5)P2 affinity was lowered by mutation. We hypothesize that different channels may be associated with distinct pools of PI(4,5)P2 that differ in their accessibility to PLC and VSPs.

  16. Ion channel regulation by phosphoinositides analyzed with VSPs – PI(4,5P2 affinity, phosphoinositide selectivity, and PI(4,5P2 pool accessibility

    Directory of Open Access Journals (Sweden)

    Alexandra eRjasanow

    2015-06-01

    Full Text Available The activity of many proteins depends on the phosphoinositide (PI content of the membrane. E.g., dynamic changes of the concentration of PI(4,5P2 are cellular signals that regulate ion channels. The susceptibility of a channel to such dynamics depends on its affinity for PI(4,5P2. Yet, measuring affinities for endogenous PIs has not been possible directly, but has relied largely on the response to soluble analogs, which may not quantitatively reflect binding to native lipids.Voltage-sensitive phosphatases (VSPs turn over PI(4,5P2 to PI(4P when activated by depolarization. In combination with voltage-clamp electrophysiology VSPs are useful tools for rapid and reversible depletion of PI(4,5P2. Because cellular PI(4,5P2 is resynthesized rapidly, steady state PI(4,5P2 changes with the degree of VSP activation and thus depends on membrane potential.Here we show that titration of endogenous PI(4,5P2 with Ci-VSP allows for the quantification of relative PI(4,5P2 affinities of ion channels. The sensitivity of inward rectifier and voltage-gated K+ channels to Ci-VSP allowed for comparison of PI(4,5P2 affinities within and across channel subfamilies and detected changes of affinity in mutant channels. The results also reveal that VSPs are useful only for PI effectors with high binding specificity among PI isoforms, because PI(4,5P2 depletion occurs at constant overall PI level. Thus, Kir6.2, a channel activated by PI(4,5P2 and PI(4P was insensitive to VSP.Surprisingly, despite comparable PI(4,5P2 affinity as determined by Ci-VSP, the Kv7 and Kir channel families strongly differed in their sensitivity to receptor-mediated depletion of PI(4,5P2. While Kv7 members were highly sensitive to activation of PLC by Gq-coupled receptors, Kir channels were insensitive even when PI(4,5P2 affinity was lowered by mutation. We hypothesize that different channels may be associated with distinct pools of PI(4,5P2 that differ in their accessibility to PLC and VSPs.

  17. Transferable tetracycline resistance in Listeria monocytogenes from food in Italy.

    Science.gov (United States)

    Pourshaban, Manoocheher; Ferrini, Anna Maria; Mannoni, Veruscka; Oliva, Brunello; Aureli, Paolo

    2002-07-01

    Mechanisms of tetracycline resistance were investigated in two recent Listeria monocytogenes isolates from food, with L. innocua 52P tet(r) as a control. Tetracycline resistance was transferred conjugatively from all three strains to L. ivanovii and from one isolate and the control to Enterococcus faecalis. Molecular analysis demonstrated a chromosomal location for the tet determinant, which was identified as tetM in all cases. These studies are the first to show that L. monocytogenes from food could be a source of tetracycline resistance genes able to spread to other micro-organisms.

  18. Variations in virulence between different electrophoretic types of Listeria monocytogenes

    DEFF Research Database (Denmark)

    Nørrung, Birgit; Andersen, Jens Kirk

    2000-01-01

    A total of 245 strains of Listeria monocytogenes, representing 33 different electrophoretic types (ETs), were examined quantitatively for haemolytic activity. No significant difference was observed in the mean haemolytic activity between different ETs. Eighty four out of 91 strains examined were...... compared with 3.64 among food isolates). The explanation for this may be that more virulent strains are more prone to cause human infection. It is, however, also possible that strains oft. monocytogenes may become more virulent while multiplying in a living organism compared with multiplying in foods....

  19. Nalaz bakterije Listeria monocytogenes u ribi i ribljim proizvodima

    OpenAIRE

    Rožman, Jelena; Njari, dr. sc. Bela; Kozačinski, dr. sc. Lidija

    2016-01-01

    Listerioza je bolest koja se prenosi hranom a bakterija Listeria monocytogenes je jedan od najznačajnijih javnozdravstvenih problema i uvjet prometa hrane u svijetu. Prije svega povezana je s konzumacijom gotovih proizvoda. U ovom radu je pretražena svježa riba (brancin) i riblji proizvodi (dimljena i marinirana riba, orada i brancin) na nalaz bakterije L. monocytogenes. Također, pretraženi su uzorci brisova uzeti s radnih površina i ruku djelatnika u pogonima prerade morske ribe. Bakterija L...

  20. Listeria monocytogenes response regulators important for stress tolerance and pathogenesis

    DEFF Research Database (Denmark)

    Kallipolitis, B H; Ingmer, H

    2001-01-01

    Environmental sensing by two-component signal transduction systems is likely to play a role for growth and survival of Listeria monocytogenes both during transmission in food products and within a host organism. Two-component systems typically consist of a membrane-associated sensor histidine...... of L. monocytogenes in mice. Strikingly, the mutants that were attenuated in virulence also had a decreased ability to grow in the presence of various stress conditions potentially encountered in an infection process. Thus, our data point to a connection between the ability of the putative two-component...

  1. Bacteriocin like substance production by Carnobacterium piscicola in a continuous system with three culture broths. Study of antagonism against Listeria monocytogenes on vacuum packaged salmon Produção de substâncias semelhantes à bacteriocinas por C. piscicola em um sistema contínuo com três meios de cultura e seu antagonismo contra L. monocytogenes em salmão embalado a vácuo

    Directory of Open Access Journals (Sweden)

    Renate P. Schöbitz

    2006-03-01

    Full Text Available Three culture media were studied for the bacteriocin like substance (BLS production from Carnobacterium piscicola L 103 in a batch and continuous culture system. The efficacy of the antagonistic substance against Listeria monocytogenes was tested on vacuum packaged salmon. BLS was produced in a 1.0 L bioreactor by batch and continuous culture using D-MRS, mod. D-MRS and APT as nutrient broths. Salmon fillets were inoculated with BLS (200 AU mL-1 and 800 AU mL-1 and 8.0 x 10¹ cfu cm-2 of L. monocytogenes and stored at 4ºC. The growth of L. monocytogenes was determined every 5 days during 15 days. After 12 h of batch culture the stationary growth phase of C. piscicola L 103 started, with a BLS activity of 800 AU mL-1 in D-MRS and mod. D-MRS broth, and of 400 AU mL-1 in APT broth. During continuous culture BLS activity increased to 6400 AU mL-1 in both types of MRS broths, while in APT the activity decreased to 50 AU mL-1, indicating a clear advantage of the first two culture media and also of the continuous culture system. BLS had a bacteriostatic effect on L. monocytogenes when inoculated on salmon, with counts of 6.0 x 10³ cfu cm-2 after 15 days. No significant differences were found between the two BLS activities used. In the control without BLS, L. monocytogenes counts increased to 1.0 x 10(6 cfu cm-2 after 15 days of storage.Três meios de cultura foram avaliados quanto a produção de substâncias semelhantes a bacteriocinas (SSB por Carnobacterium piscicola L 103, utilizando um sistema contínuo de cultura. A eficácia da substância antagonista contra Listeria monocytogenes foi testada em salmão embalado a vácuo. As SSB foram produzidas em bioreator de 1.0 L, em cultura contínua e em cultura estacionária, utilizando D-MRS, mod. D-MRS e APT como meios de cultivo. Filés de salmão foram inoculados com SSB (200 AU mL-1 e 800 AU mL-1 e L. monocytogenes (8.0 x 10¹ ufc cm-2 e mantidos a 4ºC. O crescimento de L. monocytogenes foi

  2. Amberlyst A-15: Reusable catalyst for the synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted-1-imidazoles under MW irradiation

    Indian Academy of Sciences (India)

    Shivaji S Pandit; Swapnil K Bhalerao; Uddhav S Aher; Gorakshanath L Adhav; Vikram U Pandit

    2011-07-01

    One-pot multi-component condensation of benzyl, aldehydes, ammonium acetate and primary amines were used for synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted-1-imidazole derivatives underMWradiation using amberlyst A-15 as a catalysts. This catalyst has several advantages (simple work-up, low cost and reusability).

  3. Resistencias a antibióticos en Listeria monocytogenes y Salmonella enterica aislados de alimentos de origen animal

    Directory of Open Access Journals (Sweden)

    Baltasar Balsalobre Hernández

    2004-12-01

    Full Text Available El uso extensivo de antibióticos para la salud humana y animal así como para mejorar la producción ganadera ha generado un gran número de cepas microbianas resistentes a antibióticos de uso común. Es bien conocida la difusión de resistencias a través de la terapéutica humana y animal, pero desconocemos en qué medida los alimentos de origen animal destinados a consumo humano son portadores de resistencias.En este trabajo, se investigó la sensibilidad a diecinueve antibióticos de cepas de Listeria monocytogenes y Salmonella enterica aisladas de diferentes alimentos de origen animal, como son carnes frescas, hamburguesas, salchichas y chorizos frescos, jamón cocido y huevos frescos, utilizando la técnica de difusión en placa.Las cepas de L. monocytogenes fueron muy sensibles a todos los antibióticos utilizados, con la única excepción de una cepa resistente a la tetraciclina. En cambio, en S. enterica la presencia de resistencias es muy frecuente siendo común la multi-resistencia. La mayor frecuencia de resistencias fue frente a tetraciclina, estreptomicina, ácido nalidíxico, ticarcilina, ampicilina y cloramfenicol. El veinte por ciento de las cepas mostraron resistencia a 4 o más antibióticos. Por serotipos, el mayor número de resistencias se dio en las salmonellas de serotipo 4,5,12:i:-, Hadar, Typhimurium y Virchow.Se concluye que Salmonella enterica aislada de alimentos de origen animal destinados a consumo humano es un microorganismo portador de frecuentes resistencias. El significado de esta observación y su potencial riesgo para la salud debe ser investigado. En el caso de L. monocytogenes, la presencia de resistencia no es significativa.

  4. Control of diverse subcellular processes by a single multi-functional lipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2].

    Science.gov (United States)

    Kolay, Sourav; Basu, Urbashi; Raghu, Padinjat

    2016-06-15

    Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is a multi-functional lipid that regulates several essential subcellular processes in eukaryotic cells. In addition to its well-established function as a substrate for receptor-activated signalling at the plasma membrane (PM), it is now recognized that distinct PI(4,5)P2 pools are present at other organelle membranes. However, a long-standing question that remains unresolved is the mechanism by which a single lipid species, with an invariant functional head group, delivers numerous functions without loss of fidelity. In the present review, we summarize studies that have examined the molecular processes that shape the repertoire of PI(4,5)P2 pools in diverse eukaryotes. Collectively, these studies indicate a conserved role for lipid kinase isoforms in generating functionally distinct pools of PI(4,5)P2 in diverse metazoan species. The sophistication underlying the regulation of multiple functions by PI(4,5)P2 is also shaped by mechanisms that regulate its availability to enzymes involved in its metabolism as well as molecular processes that control its diffusion at nanoscales in the PM. Collectively, these mechanisms ensure the specificity of PI(4,5)P2 mediated signalling at eukaryotic membranes.

  5. Urban prevalence of Listeria spp. and Listeria monocytogenes in public lavatories and on shoe soles of facility patrons in the European capital city Vienna.

    Science.gov (United States)

    Schoder, D; Schmalwieser, A; Szakmary-Brändle, K; Stessl, B; Wagner, M

    2015-05-01

    The aim of this study was to determine the prevalence of Listeria spp. and Listeria monocytogenes (L. monocytogenes) in urban public lavatories and on shoe soles of facility patrons in a European capital city. More than 91% of all municipal public lavatories in Vienna close to public hubs were included in this study. Overall, 373 swab samples of public lavatories and shoes of facility patrons were enriched, according to ISO 11290-1. Listeria monocytogenes isolates were subtyped using pulsed-field gel electrophoresis. A total of 24 samples were positive for Listeria spp., yielding an overall prevalence of 6.4% (24/373). Listeria monocytogenes was found in 2.1% (8/373) of all samples. Swabs from lavatories in parks, container lavatories and lavatories at markets had the highest prevalences of 20.7% (6/29), 20% (2/10) and 12.5% (1/8) Listeria spp., respectively. These detection rates were statistically significantly higher than those associated with lavatories in shopping centres (P = 0.003, P = 0.002, P = 0.02) and at public transport locations (P = 0.0004, P = 0.005, P = 0.02). Shoes sampled at Christmas markets showed the highest Listeria spp. and L. monocytogenes prevalences of 80% (4/5) and 40% (2/5), respectively. With regard to shoe type, Listeria spp. detection rates were 14.3% (3/21; winter boots), 13.3% (2/15; hiking boots), sport shoes (5.9%; 2/34) and brogues (5.1%; 4/79). No Listeria spp. were found on shoe soles that had smooth treads (0/76), while Listeria spp. were detected on 19.5% (8/41) of medium depth tread shoe types and on 9.4% (3/32) of deep tread shoes. These data suggest that soil environment is still one of the most important reservoirs for the foodborne pathogen L. monocytogenes. © 2014 Blackwell Verlag GmbH.

  6. Influence of temperature on alkali stress adaptation in Listeria monocytogenes

    Science.gov (United States)

    Listeria monocytogenes cells may induce alkali stress adaptation when exposed to sublethal concentrations of alkaline cleaners and sanitizers that may be frequently used in the food processing environment. In the present study, the effect of temperature on the induction and the stability of such alk...

  7. LISTERIA MONOCYTOGENES IN THE CONTEXT OF THE NEW COMMUNITY REGULATIONS

    Directory of Open Access Journals (Sweden)

    A. Bragagnolo

    2008-02-01

    Full Text Available In recent years in the countries of the European Union have occurred profound and radical changes regarding the safety and hygiene of foodstuffs. The aim of this work is to highlight the significant changes made by the recent legislation in the control of Listeria monocytogenes.

  8. Studies on the risk assessment of Listeria monocytogenes

    NARCIS (Netherlands)

    Notermans, S.; Dufrenne, J.; Teunis, P.; Chackraborty, T.

    1998-01-01

    Humans are frequently exposed to Listeria monocytogenes, and high numbers may be ingested during consumption of certain types of food. However, epidemiological investigations show that listeriosis is a rare disease. Risk assessment studies using an animal mouse model indicate that almost all L. mono

  9. Overlevingsstrategieën Listeria monocytogenes bij lage temperatuur

    NARCIS (Netherlands)

    Wemekamp-Kamphuis, H.H.; Abee, T.

    2004-01-01

    Listeria monocytogenes is an important food-borne pathogen that may cause severe infections in humans. Many outbreaks caused by this organism have been associated with ready-to-eat foods wich may have undergone some form of minimal processing, or have been contaminated after processing. Ready-to-eat

  10. Neonatal infection with Listeria monocytogenes: Rare, but serious

    NARCIS (Netherlands)

    Van Stuijvenberg, M.; Spanjaard, L.; Bergman, K.A.

    2006-01-01

    Between 1993 and 2003, three infants, two girls and a boy, were found to have an invasive infection with Listeria monocytogenes. They received intensive care including respiratory and circulatory support, antibiotics, and treatment of the neurological complications when possible. One of the girls

  11. Listeria monocytogenes and hemolytic Listeria innocua in poultry.

    Science.gov (United States)

    Milillo, S R; Stout, J C; Hanning, I B; Clement, A; Fortes, E D; den Bakker, H C; Wiedmann, M; Ricke, S C

    2012-09-01

    Listeria monocytogenes is a ubiquitous, saprophytic, Gram-positive bacterium and occasional food-borne pathogen, often associated with ready-to-eat meat products. Because of the increased consumer interest in organic, all natural, and free range poultry products, it is important to understand L. monocytogenes in the context of such systems. Pasture-reared poultry were surveyed over the course of two 8-wk rearing periods. Cecal, soil, and grass samples were collected for Listeria isolation and characterization. Seven of 399 cecal samples (or 1.75%) were Listeria-positive. All positive cecal samples were obtained from broilers sampled at 2 wk of age. Grass and soil samples were collected from the pasture both before and after introduction of the poultry. Environmental samples collected after introduction of poultry were significantly more likely to contain Listeria (P Listeria, sigB allelic typing, and hlyA PCR tests found that both L. monocytogenes and L. innocua, including hemolytic L. innocua, were recovered from the cecal and environmental (grass/soil) samples. The sigB allelic typing also revealed that (1) positive samples could be composed of 2 or more allelic types; (2) allelic types found in cecal samples could also be found in the environment; and (3) allelic types could persist through the 2 rearing periods. Our data indicate that both pasture-reared poultry and their environment can be contaminated with L. monocytogenes and hemolytic L. innocua.

  12. Presence of Listeria monocytogenes in silage products of Shahrekord city

    Directory of Open Access Journals (Sweden)

    Ali Sharifzadeh

    2015-06-01

    Full Text Available Objective: To investigate the presence of Listeria monocytogenes in the silage samples. Methods: Silage samples obtained from 150 different farms in Shahrekord city (Iran and after DNA extraction, all samples were analyzed by PCR technique using one pair of primers for presence of this pathogen. The amplified products were detected on 1.5% agarose gel electrophoresis. Results: Listeria monocytogenes was isolated in 4 (2% of the 150 samples. The detection of this bacterium from silage samples in Shahrekord city indicated that these products could create a serious risk in public health of animal and human. The findings showed that in positive silage samples for Listeria monocytogenes, the pH value was about five and it was due to bacterial activity in these products. Conclusions: The quality of silage and hygiene parameters and good herd health management play an important role in the microbiological quality of herd and farm. Considering the high specificity and sensitivity of the employed PCR technique, it is recommended to be useful technique for identification of Listeria monocytogenes.

  13. Listeria monocytogenes : the nature, public health aspects and ...

    African Journals Online (AJOL)

    Animal Production Research Advances ... New food borne infectious diseases have continued to emerge world over in the food industries. ... Its' public health importance cannot be over emphasized as L. monocytogenes causes huge economic ... It is therefore, suggested that proper control strategies, good quality control ...

  14. Quantifying strain variability in modeling growth of Listeria monocytogenes

    NARCIS (Netherlands)

    Aryani, D.; Besten, den H.M.W.; Hazeleger, W.C.; Zwietering, M.H.

    2015-01-01

    Prediction of microbial growth kinetics can differ from the actual behavior of the target microorganisms. In the present study, the impact of strain variability on maximum specific growth rate (µmax) (h- 1) was quantified using twenty Listeria monocytogenes strains. The µmax was determined as functi

  15. Genome sequesnce of lineage III Listeria monocytogenes strain HCC23

    Science.gov (United States)

    More than 98% of reported human listeriosis cases are caused by Listeria monocytogenes serotypes within lineages I and II. Serotypes within lineage III (4a and 4c) are commonly isolated from environmental and food specimens. We report the first complete genome sequence of a lineage III isolate, HCC2...

  16. Inhibition of Listeria monocytogenes by fatty acids and monoglycerides.

    Science.gov (United States)

    Wang, L L; Johnson, E A

    1992-02-01

    Fatty acids and monoglycerides were evaluated in brain heart infusion broth and in milk for antimicrobial activity against the Scott A strain of Listeria monocytogenes. C12:0, C18:3, and glyceryl monolaurate (monolaurin) had the strongest activity in brain heart infusion broth and were bactericidal at 10 to 20 micrograms/ml, whereas potassium (K)-conjugated linoleic acids and C18:2 were bactericidal at 50 to 200 micrograms/ml. C14:0, C16:0, C18:0, C18:1, glyceryl monomyristate, and glyceryl monopalmitate were not inhibitory at 200 micrograms/ml. The bactericidal activity in brain heart infusion broth was higher at pH 5 than at pH 6. In whole milk and skim milk, K-conjugated linoleic acid was bacteriostatic and prolonged the lag phase especially at 4 degrees C. Monolaurin inactivated L. monocytogenes in skim milk at 4 degrees C, but was less inhibitory at 23 degrees C. Monolaurin did not inhibit L. monocytogenes in whole milk because of the higher fat content. Other fatty acids tested were not effective in whole or skim milk. Our results suggest that K-conjugated linoleic acids or monolaurin could be used as an inhibitory agent against L. monocytogenes in dairy foods.

  17. The Continuous Challenge of Characterizing the Foodborne Pathogen Listeria monocytogenes.

    Science.gov (United States)

    Camargo, Anderson Carlos; Woodward, Joshua John; Nero, Luís Augusto

    2016-08-01

    Listeria monocytogenes is an important foodborne pathogen commonly isolated from food processing environments and food products. This organism can multiply at refrigeration temperatures, form biofilms on different materials and under various conditions, resist a range of environmental stresses, and contaminate food products by cross-contamination. L. monocytogenes is recognized as the causative agent of listeriosis, a serious disease that affects mainly individuals from high-risk groups, such as pregnant women, newborns, the elderly, and immunocompromised individuals. Listeriosis can be considered a disease that has emerged along with changing eating habits and large-scale industrial food processing. This disease causes losses of billions of dollars every year with recalls of contaminated foods and patient medical treatment expenses. In addition to the immune status of the host and the infecting dose, the virulence potential of each strain is crucial for the development of disease symptoms. While many isolates are naturally virulent, other isolates are avirulent and unable to cause disease; this may vary according to the presence of molecular determinants associated with virulence. In the last decade, the characterization of genetic profiles through the use of molecular methods has helped track and demonstrate the genetic diversity among L. monocytogenes isolates obtained from various sources. The purposes of this review were to summarize the main methods used for isolation, identification, and typing of L. monocytogenes and also describe its most relevant virulence characteristics.

  18. Overlevingsstrategieën Listeria monocytogenes bij lage temperatuur

    NARCIS (Netherlands)

    Wemekamp-Kamphuis, H.H.; Abee, T.

    2004-01-01

    Listeria monocytogenes is an important food-borne pathogen that may cause severe infections in humans. Many outbreaks caused by this organism have been associated with ready-to-eat foods wich may have undergone some form of minimal processing, or have been contaminated after processing. Ready-to-eat

  19. Whole genome sequence-based serogrouping of Listeria monocytogenes isolates.

    Science.gov (United States)

    Hyden, Patrick; Pietzka, Ariane; Lennkh, Anna; Murer, Andrea; Springer, Burkhard; Blaschitz, Marion; Indra, Alexander; Huhulescu, Steliana; Allerberger, Franz; Ruppitsch, Werner; Sensen, Christoph W

    2016-10-10

    Whole genome sequencing (WGS) is currently becoming the method of choice for characterization of Listeria monocytogenes isolates in national reference laboratories (NRLs). WGS is superior with regards to accuracy, resolution and analysis speed in comparison to several other methods including serotyping, PCR, pulsed field gel electrophoresis (PFGE), multilocus sequence typing (MLST), multilocus variable number tandem repeat analysis (MLVA), and multivirulence-locus sequence typing (MVLST), which have been used thus far for the characterization of bacterial isolates (and are still important tools in reference laboratories today) to control and prevent listeriosis, one of the major sources of foodborne diseases for humans. Backward compatibility of WGS to former methods can be maintained by extraction of the respective information from WGS data. Serotyping was the first subtyping method for L. monocytogenes capable of differentiating 12 serovars and national reference laboratories still perform serotyping and PCR-based serogrouping as a first level classification method for Listeria monocytogenes surveillance. Whole genome sequence based core genome MLST analysis of a L. monocytogenes collection comprising 172 isolates spanning all 12 serotypes was performed for serogroup determination. These isolates clustered according to their serotypes and it was possible to group them either into the IIa, IIc, IVb or IIb clusters, respectively, which were generated by minimum spanning tree (MST) and neighbor joining (NJ) tree data analysis, demonstrating the power of the new approach. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  20. Influence of temperature on alkali stress adaptation in Listeria monocytogenes

    Science.gov (United States)

    Listeria monocytogenes cells may induce alkali stress adaptation when exposed to sublethal concentrations of alkaline cleaners and sanitizers that may be frequently used in the food processing environment. In the present study, the effect of temperature on the induction and the stability of such alk...

  1. Studies on the risk assessment of Listeria monocytogenes

    NARCIS (Netherlands)

    Notermans, S.; Dufrenne, J.; Teunis, P.; Chackraborty, T.

    1998-01-01

    Humans are frequently exposed to Listeria monocytogenes, and high numbers may be ingested during consumption of certain types of food. However, epidemiological investigations show that listeriosis is a rare disease. Risk assessment studies using an animal mouse model indicate that almost all L.

  2. Effects of Two Application Methods of Plantaricin BM-1 on Control of Listeria monocytogenes and Background Spoilage Bacteria in Sliced Vacuum-Packaged Cooked Ham Stored at 4°C.

    Science.gov (United States)

    Zhou, Huimin; Xie, Yuanhong; Liu, Hui; Jin, Junhua; Duan, Huixia; Zhang, Hongxing

    2015-10-01

    Two application methods were used to investigate the effect of plantaricin BM-1 on the control of Listeria monocytogenes and background spoilage bacteria in sliced vacuum-packaged cooked ham without the addition of any chemical preservatives, including sodium nitrite, during 35 days of storage at 4°C. Regardless of the application method, plantaricin BM-1 treatment (320, 640, or 1,280 arbitrary units [AU]/g of sliced cooked ham) significantly (P < 0.05) reduced the survival of L. monocytogenes (inoculated at 4 log CFU/g of sliced ham) compared with its survival in the control during the first 21 days of storage at 4°C. The inhibitory effect of plantaricin applied to the surface of the ham was significantly better than the same concentration of plantaricin incorporated into the cooked ham (P < 0.0001) during storage. Even 320 AU/g plantaricin applied to the surface exhibited greater inhibition of L. monocytogenes than 1,280 AU/g plantaricin incorporated into the cooked ham on days 1, 14, and 28. A level of 1,280 AU/g plantaricin applied to the surface of the ham reduced L. monocytogenes counts to below the detection limit from the 1st to the 21st day of storage at 4°C. Afterwards, L. monocytogenes was able to regrow, and the viable counts of L. monocytogenes at the end of storage reached 2.76 log CFU/g (6.11 log CFU/g lower than in the control). In the control ham, the counts of background spoilage bacteria increased gradually and surpassed the microbiological spoilage limitation level on the 21st day of storage. However, plantaricin BM-1 treatment significantly (P < 0.05) reduced the survival of background spoilage bacteria in ham compared with their survival in the control from day 21 to 35 of storage at 4°C. A level of 1,280 AU/g plantaricin incorporated into cooked ham was the most effective, reducing the count of background spoilage bacteria count from an initial 2.0 log CFU/g to 1.5 log CFU/g on day 7. This was then maintained for another 14 days and

  3. Fading of inoculation effects in ductile iron

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2008-03-01

    Full Text Available In work i t has bccn shown rcsults or invcsligations of influcncc of rime Iapsed form inoculation proccss on graphitc nucleation potentialrcprcscntcd by: numbcr of graphitc nodulcs N and N,, maximum undercooling AT,, during solidification of gmphile eutcct ic. abmlutcchilling tcndcncy CT and critical casting diametct dh. undcr which cementite euteclic occur (so-callcd chills. Morcovcr it has hccncstima~cd raic of changc of N and N, AT,,,. CT and dk,. Also, it has bccn provcd that altcr onc minutc sincc rhc momcnt of inocuIationproccss nhout 35% of prnphttc nucIeation potenrial is tost. by 40% chitking tendency, by 70% incrcascs maximum undcrcmling forgraphitc ci~tccrica nd by nearly 40% caging diameter has to bc incrcascd in ordcr to avoid chills.

  4. Thermal inactivation kinetics of surface contaminating Listeria monocytogenes on vacuum-packaged agar surface and ready-to-eat sliced ham and sausage.

    Science.gov (United States)

    Wang, Xiang; Uyttendaele, Mieke; Geeraerd, Annemie; Steen, Liselot; Fraeye, Ilse; Devlieghere, Frank

    2016-11-01

    The aim of this work was to study thermal inactivation kinetics of Listeria monocytogenes on vacuum-packaged food surfaces. The kinetics were first determined on model agar systems (BHI agar plates), mimicking cooked meat products, which have the same characteristics (pH, sodium chloride (NaCl) or sodium lactate (NaL) content and thickness) as the cooked meat products. Then, in order to validate how well the thermal inactivation on the model agar system simulated inactivation on real products, inactivation kinetics of L. monocytogenes on slices of cooked ham and cooked sausage were examined. BHI agar plates (pH6.2 or 7.2) were prepared with and without the addition of 3% NaCl or NaL. They were initially inoculated with approximately 10(9)CFU/plate culture, aseptically packaged in linear low-density polyethylene pouches, and vacuum-sealed. Thermal treatments were performed by submerging packages in a water bath maintained at 60°C. For most of the conditions studied, the inactivation curves were linear; shoulders were only observed for curves at conditions of pH6.2 with 3.0% NaL. The t4D values (time needed to obtain an inactivation of four-log reduction) were calculated based on the best fitting models included in GInaFit. The observed t4D values for L. monocytogenes on agar surfaces ranged from 6.8 (pH6.2) to 13.7min (pH7.2 with 3.0% NaCl). At pH6.2 addition of NaCl or NaL significantly increased the heat resistance of L. monocytogenes while at pH7.2 this effect was not significant. NaL seemed to affect the heat resistance to the same extent as NaCl. Inactivation curves of L. monocytogenes on slices of cooked ham at pH6.2 with or without addition of NaCl or NaL appeared to be log-linear in shape. However, the curves obtained from cooked sausages were markedly concave and the Weibull model was used for fitting. Concerning heat resistance of L. monocytogenes on meat products, t4D values increased approximately two-fold compared to those corresponding on model agar

  5. Pharmacological Characterization of Inositol 1,4,5-tris Phosphate Receptors in Human Platelet Membranes

    Directory of Open Access Journals (Sweden)

    Yogesh Dwivedi

    2009-01-01

    Full Text Available The phosphatidylinositol (PI hydrolysis signaling system has been shown to be altered in platelets of depressed and schizophrenic subjects. Inositol (1,4,5 trisphosphate (Ins(1,4,5P3, an integral component of the PI signaling system, mobilizes Ca2+ by activating Ins(1,4,5P3 receptors. To eventually investigate the role of Ins(1,4,5P3 receptors in depression and other mental disorders, we characterized [H3]Ins(1,4,5P3 binding sites in crude platelet membranes prepared from small amounts of blood obtained from healthy human control subjects. We found a single, saturable binding site for [H3]Ins(1,4,5P3 to crude platelet membranes, which is time dependent and modulated by pH, inositol phosphates, and heparin. Since cyclic adenosine monophosphate (cAMP and Ca2+ have been shown to be important modulators in Ins(1,4,5P3 receptors, in the present study we also determined the effects of various concentrations of CaCI2 and forskolin on Ins(1,4,5P3 binding to platelet membranes. CaCI2 modulated [3H]Ins(1,4,5P3 binding sites in a biphasic manner: at lower concentrations it inhibited [3H]Ins(1,4,5P3 binding, whereas at higher concentrations, it stimulated [3H]Ins(1,4,5P3 binding. On the other hand, forskolin inhibited [3H]Ins(1,4,5P3 binding. Our results thus suggest that the pharmacological characteristics of [3H]Ins(1,4,5P3 binding to crude platelet membranes are similar to that of Ins(1,4,5P3 receptors; and that both Ca2+ and cAMP modulate [3H]Ins(1,4,5P3 binding in crude platelet membranes.

  6. Hot water postprocess pasteurization of cook-in-bag turkey breast treated with and without potassium lactate and sodium diacetate and acidified sodium chlorite for control of Listeria monocytogenes.

    Science.gov (United States)

    Luchansky, John B; Cocoma, George; Call, Jeffrey E

    2006-01-01

    Surface pasteurization and food-grade chemicals were evaluated for the ability to control listeriae postprocess on cook-in-bag turkey breasts (CIBTB). Individual CIBTB were obtained directly from a commercial manufacturer and surface inoculated (20 ml) with a five-strain cocktail (ca. 7.0 log) of Listeria innocua. In each of two trials, the product was showered or submerged for up to 9 min with water heated to 190, 197, or 205 degrees F (ca. 87.8, 91.7, or 96.1 degrees C) in a commercial pasteurization tunnel. Surviving listeriae were recovered from CIBTB by rinsing and were then enumerated on modified Oxford agar plates following incubation at 37 degrees C for 48 h. As expected, higher water temperatures and longer residence times resulted in a greater reduction of L. innocua. A ca. 2.0-log reduction was achieved within 3 min at 205 and 197 degrees F and within 7 min at 190 degrees E In related experiments, the following treatments were evaluated for control of Listeria monocytogenes on CIBTB: (i) a potassium lactate-sodium diacetate solution (1.54% potassium lactate and 0.11% sodium diacetate) added to the formulation in the mixer and 150 ppm of acidified sodium chlorite applied to the surface with a pipette, or (ii) a potassium lactate-sodium diacetate solution only, or (iii) no potassium lactate-sodium diacetate solution and no acidified sodium chlorite. Each CIBTB was inoculated (20 ml) with ca. 5 log CFU of a five-strain mixture of L. monocytogenes and then vacuum sealed. In each of two trials, half of the CIBTB were exposed to 203 degrees F water for 3 min in a pasteurization tunnel, and the other half of the CIBTB were not; then, all CIBTB were stored at 4 degrees C for up to 60 days, and L. monocytogenes was enumerated by direct plating onto modified Oxford agar. Heating resulted in an initial reduction of ca. 2 log CFU of L. monocytogenes per CIBTB. For heated CIBTB, L. monocytogenes increased by ca. 2 log CFU per CIBTB in 28 (treatment 1), 28 (treatment

  7. Inactivation of several strains of Listeria monocytogenes attached to the surface of packaging material by Na-Chlorophyllin-based photosensitization.

    Science.gov (United States)

    Luksiene, Zivile; Buchovec, Irina; Paskeviciute, Egle

    2010-12-02

    This study was focused on the possibility to inactivate thermosensitive Listeria monocytogenes ATC(L3)C 7644 and thermoresistant 56 Ly strain by Na-Chlorophyllin (Na-Chl)-based photosensitization in vitro and on the surface of packaging. Comparative analysis of antimicrobial efficiency of photosensitization with conventional surface cleaning was performed. Data indicate that both Listeria strains, after incubation with Na-Chl and following illumination (λ=400nm, 20mWcm(-2)), were inactivated by 7 log in vitro. This treatment cleaned both Listeria strains from packaging surfaces. Comparative analysis indicates that washing with water diminishes pathogens by less than 1 log, 200ppm Na-hypochlorite by 1.7 log, Na-Chl-based photosensitization by 4.5 log. Listeria biofilms were totally removed from the surface by photosensitization at higher photosensitizer concentrations and longer incubation times. In conclusion, both strains of L. monocytogenes can be effectively inactivated by photosensitization in vitro and on the surface of packaging. Listeria biofilms are susceptible to this treatment as well. Comparison of different surface decontamination treatments reveals that photosensitization is much more effective against both Listeria strains than washing with water or 200ppm Na-hypochlorite. Our data support the idea that Na-Chl-based photosensitization is an effective antimicrobial tool which may serve in the future for the development of human and environmentally friendly surface decontamination techniques.

  8. Prevalence and antibiotic susceptibility of Listeria monocytogenes in raw milk from cattle herds within Sokoto Metropolis, Nigeria

    Directory of Open Access Journals (Sweden)

    ML Gulumbe

    2012-12-01

    Full Text Available One hundred and ninety two raw milk samples were collected from lactating cows identified in Fulani herds and small scale dairy farms within Sokoto metropolis in order to investigate the presence and determine the antibiotic susceptibility of Listeria monocytogenes in the milk. Selective culture and identification method was employed for the bacterial isolation and Kirby-Bauer technique was used for the antibiotic susceptibility test. Seventy six samples (39.58% were positive for Listeria species, which upon biochemical characterization 39(51.3% were Listeria innocua, 14(18.4% Listeria ivanovii, 17(22.4% Listeria monocytogenes, 4(5.3% Listeria welshimeri and 2(2.6% Listeria seeligeri. Antibiotic susceptibility test of the isolates revealed high resistance to ampicillin (100%, and streptomycin (80%, followed by ampiclox (70%, tetracycline (30%, then gentamycin (20% while, there was no resistance to ciprofloxacin and chloranphenicol. The findings of this study necessitate the need for extension personnel to educate the Fulani herdsmen, milk handlers and other livestock producers on the significance of hygiene especially during milking and the effect of indiscriminate use of drugs particularly antibiotics. There is also need for the agencies concerned such as the National Agency for Food and Drugs Administration and Control (NAFDAC to regulate the sales and use of both human and veterinary drugs by drug hawkers and other non-professional veterinary practitioners.

  9. Prevalence of Listeria monocytogenes in poultry production in France.

    Science.gov (United States)

    Chemaly, Marianne; Toquin, Marie-Therese; Le Nôtre, Yolene; Fravalo, Philippe

    2008-10-01

    This study aimed to update and create a data set from laying hens and broilers regarding contamination by Listeria monocytogenes. Two hundred laying-hen flocks were sampled, with 88 flocks reared in cages and 112 reared on the floor. One hundred forty-five broiler flocks were sampled, with 85 conventional and 60 free-range flocks. A total of 774 and 725 samples were analyzed from laying hens and broilers, respectively. L. monocytogenes was detected in 31 of 200 flocks, yielding an estimated prevalence of 15.5% in laying-hen flocks. Among positive flocks, there appeared a significant (P = 0.004) difference between caged and floor-reared hens, with a higher detection in dust samples from floor-reared hens. In positive caged hen flocks, significant (P = 0.028) differences between dust and fecal samples appeared, with a higher detection in feces than in dust samples. In broiler flocks, L. monocytogenes was isolated in 46 of 145 flocks, yielding an estimated prevalence of 32% (28% in conventional flocks versus 37% in the free-range flocks). L. monocytogenes was isolated in samples taken from conventional flocks with a lower frequency than in free-range flocks (13 versus 18%, respectively). The serotyping of L. monocytogenes strains showed that the majority belonged to type 1/2a in laying-hen flocks (74.3%) and in broiler flocks (40.5%). A significant difference (P = 0.007) between laying hens and broilers was shown for serogroup 4 and for serovar 1/2b (P = 0.007); these serogroups were more prevalent in broilers (40%) than in laying hens (5.7%).

  10. n-3 polyunsaturated fatty acids suppress CD4(+) T cell proliferation by altering phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P2] organization.

    Science.gov (United States)

    Hou, Tim Y; Barhoumi, Rola; Fan, Yang-Yi; Rivera, Gonzalo M; Hannoush, Rami N; McMurray, David N; Chapkin, Robert S

    2016-01-01

    The mechanisms by which n-3 polyunsaturated fatty acids (n-3 PUFA), abundant in fish oil, exert their anti-inflammatory effects have not been rigorously defined. We have previously demonstrated that n-3 PUFA decrease the amount of phosphatidylinositol-(4,5)-bisphosphate, [PI(4,5)P2], in CD4(+) T cells, leading to suppressed actin remodeling upon activation. Since discrete pools of PI(4,5)P2 exist in the plasma membrane, we determined whether n-3 PUFA modulate spatial organization of PI(4,5)P2 relative to raft and non-raft domains. We used Förster resonance energy transfer (FRET) to demonstrate that lipid raft mesodomains in the plasma membrane of CD4(+) T cells enriched in n-3 PUFA display increased co-clustering of Lck(N10) and LAT(ΔCP), markers of lipid rafts. CD4(+) T cells enriched in n-3 PUFA also exhibited a depleted plasma membrane non-raft PI(4,5)P2 pool as detected by decreased co-clustering of Src(N15), a non-raft marker, and PH(PLC-δ), a PI(4,5)P2 reporter. Incubation with exogenous PI(4,5)P2 rescued the effects on the non-raft PI(4,5)P2 pool, and reversed the suppression of T cell proliferation in CD4(+) T cells enriched with n-3 PUFA. Furthermore, CD4(+) T cells isolated from mice fed a 4% docosahexaenoic acid (DHA)-enriched diet exhibited a decrease in the non-raft pool of PI(4,5)P2, and exogenous PI(4,5)P2 reversed the suppression of T cell proliferation. Finally, these effects were not due to changes to post-translational lipidation, since n-3 PUFA did not alter the palmitoylation status of signaling proteins. These data demonstrate that n-3 PUFA suppress T cell proliferation by altering plasma membrane topography and the spatial organization of PI(4,5)P2.

  11. 1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

    Science.gov (United States)

    Mielgo, Antonia

    2016-01-01

    Summary Asymmetric catalysis represents a very powerful tool for the synthesis of enantiopure compounds. In this context the main focus has been directed not only to the search for new efficient chiral catalysts, but also to the development of efficient pronucleophiles. This review highlights the utility and first examples of 1H-imidazol-4(5H)-ones and thiazol-4(5H)-ones as pronucleophiles in catalytic asymmetric reactions. PMID:27340482

  12. 1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis.

    Science.gov (United States)

    Mielgo, Antonia; Palomo, Claudio

    2016-01-01

    Asymmetric catalysis represents a very powerful tool for the synthesis of enantiopure compounds. In this context the main focus has been directed not only to the search for new efficient chiral catalysts, but also to the development of efficient pronucleophiles. This review highlights the utility and first examples of 1H-imidazol-4(5H)-ones and thiazol-4(5H)-ones as pronucleophiles in catalytic asymmetric reactions.

  13. Listeria monocytogenes survival of UV-C radiation is enhanced by presence of sodium chloride, organic food material and by bacterial biofilm formation.

    Science.gov (United States)

    Bernbom, N; Vogel, B F; Gram, L

    2011-05-14

    The bactericidal effect on food processing surfaces of ceiling-mounted UV-C light (wavelength 254 nm) was determined in a fish smoke house after the routine cleaning and disinfection procedure. The total aerobic counts were reduced during UV-C light exposure (48 h) and the number of Listeria monocytogenes positive samples went from 30 (of 68) before exposure to 8 (of 68). We therefore in a laboratory model determined the L. monocytogenes reduction kinetics by UV-C light with the purpose of evaluating the influence of food production environmental variables, such as presence of NaCl, organic material and the time L. monocytogenes was allowed to adhere to steel before exposure. L. monocytogenes grown and attached in tryptone soy broth (TSB) with glucose were rapidly killed (after 2 min) by UV-C light. However, bacteria grown and adhered in TSB with glucose and 5% NaCl were more resistant and numbers declined with 4-5 log units during exposure of 8-10 min. Bacteria grown in juice prepared from cold-smoked salmon were protected and numbers were reduced with 2-3 log when UV-C light was used immediately after attachment whereas numbers did not change at all if bacteria had been allowed to form a biofilm for 7 days before exposure. It is not known if this enhanced survival is due to physiological changes in the attached bacterial cells, a physical protection of the cells in the food matrix or a combination. In conclusion, we demonstrate that UV-C light is a useful extra bacteriocidal step and that it, as all disinfecting procedures, is hampered by the presence of organic material.

  14. Characterization of Listeria monocytogenes from three countries and antibiotic resistance differences among countries and Listeria monocytogenes serogroups.

    Science.gov (United States)

    Obaidat, M M; Bani Salman, A E; Lafi, S Q; Al-Abboodi, A R

    2015-06-01

    A total of 104 Listeria monocytogenes isolates from 330 fish samples from three countries were characterized by multiplex PCR for serogrouping and virulence markers determination and tested for antibiotics resistance. A 53·8% of the isolates belonged to serogroup 1/2a, 3a; 32% belonged to 1/2b, 3b, 7; 14·4% belonged to 4b, 4d, 4e and 1% belonged to 1/2c, 3c. All isolates exhibited resistance to at least one antibiotic but the resistance rates varied among countries. The isolates exhibited high resistance to penicillin, rifampicin, clindamycin, erythromycin and tetracycline, but low resistance to amoxicillin-clavulanic acid, streptomycin, sulfamethoxazole-trimethoprim, gentamicin, chloramphenicol and kanamycin. When comparing countries, the resistance rate for rifampicin, clindamycin, erythromycin, tetracycline, amoxicillin-clavulanic acid varied among countries. When comparing serogroup, 1/2a, 3a exhibited the highest resistance to clindamycin, erythromycin, tetracycline and vancomycin while serogroup 4b, 4d, 4e exhibited the highest resistance to amoxicillin-clavulanic acid. All isolates carried inlA, inlC, inlJ and lmo2672. Listeriolysin S was carried by 42 and 30% of 4b and 1/2b isolates respectively. Significance and impact of the study: This is one of few studies to correlate antibiotic resistance with Listeria monocytogenes serogroups. The study also compared the antibiotic resistance and serogroups of L. monocytogenes isolates from three countries in one single study. The findings of this study will be helpful in improving data on the antibiotics resistance of L. monocytogenes in developing countries and enriches the epidemiological and public health studies of L. monocytogenes. © 2015 The Society for Applied Microbiology.

  15. Effect of octenidine hydrochloride on planktonic cells and biofilms of Listeria monocytogenes.

    Science.gov (United States)

    Amalaradjou, Mary Anne Roshni; Norris, Carol E; Venkitanarayanan, Kumar

    2009-06-01

    Listeria monocytogenes is a food-borne pathogen capable of forming biofilms and persisting in food processing environments for extended periods of time, thereby potentially contaminating foods. The efficacy of octenidine hydrochloride (OH) for inactivating planktonic cells and preformed biofilms of L. monocytogenes was investigated at 37, 21, 8, and 4 degrees C in the presence and absence of organic matter (rehydrated nonfat dry milk). OH rapidly killed planktonic cells and biofilms of L. monocytogenes at all four temperatures. Moreover, OH was equally effective in killing L. monocytogenes biofilms on polystyrene and stainless steel matrices in the presence and absence of organic matter. The results underscore OH's ability to prevent establishment of L. monocytogenes biofilms by rapidly killing planktonic cells and to eliminate preformed biofilms, thus suggesting that it could be used as a disinfectant to prevent L. monocytogenes from persisting in food processing environments.

  16. Inhibition of listeriolysin O oligomerization by lutein prevents Listeria monocytogenes infection.

    Science.gov (United States)

    Liu, Bowen; Teng, Zihao; Wang, Jianfeng; Lu, Gejin; Deng, Xuming; Li, Li

    2017-01-01

    The foodborne pathogenic bacterial species Listeria monocytogenes (L. monocytogenes) has caused incalculable damages to public health, and its successful infection requires various virulence factors, including Listeriolysin O (LLO). By forming pores in phagosomal membranes and even in some organelles, LLO plays an indispensable role in the ability of L. monocytogenes to escape from host immune attacks. Because of its critical role, LLO offers an appropriate therapeutic target against L. monocytogenes infection. Here, lutein, a natural small molecule existing widely in fruits and vegetables, is demonstrated as an effective inhibitor of LLO that works by blocking its oligomerization during invasion without showing significant bacteriostatic activity. Further assays applying lutein in cell culture models of invasion and in animal models showed that lutein could effectively inhibit L. monocytogenes infection. Overall, our results indicate that lutein may represent a promising and novel therapeutic agent against L. monocytogenes infection. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Detection of Listeria monocytogenes in CSF from Three Patients with Meningoencephalitis by Next-Generation Sequencing

    Science.gov (United States)

    Yao, Ming; Zhou, Jiali; Zhu, Yicheng; Zhang, Yinxin; Lv, Xia; Sun, Ruixue; Shen, Ao; Ren, Haitao; Cui, Liying

    2016-01-01

    Background and Purpose Encephalitis caused by Listeria monocytogenes (L. monocytogenes) is rare but sometimes fatal. Early diagnosis is difficult using routine cerebrospinal fluid (CSF) tests, while next-generation sequencing (NGS) is increasingly being used for the detection and characterization of pathogens. Methods This study set up and applied unbiased NGS to detect L. monocytogenes in CSF collected from three cases of clinically suspected listeria meningoencephalitis. Results Three cases of patients with acute/subacute meningoencephalitis are reported. Magnetic resonance imaging and blood cultures led to a suspected diagnosis of L. monocytogenes, while the CSF cultures were negative. Unbiased NGS of CSF identified and sequenced reads corresponding to L. monocytogenes in all three cases. Conclusions This is the first report highlighting the feasibility of applying NGS of CSF as a diagnostic method for central nervous system (CNS) L. monocytogenes infection. Routine application of this technology in clinical microbiology will significantly improve diagnostic methods for CNS infectious diseases.

  18. Application of gamma irradiation for inactivation of three pathogenic bacteria inoculated into meatballs

    Science.gov (United States)

    Gumus, Tuncay; Şukru Demirci, A.; Murat Velioglu, H.; Velioglu, Serap D.; Yilmaz, Ismail; Sagdic, Osman

    2008-09-01

    In this research, the effect of gamma irradiation on the inactivation of Escherichia coli O157:H7 (ATCC 33150), Staphylococcus aureus (ATCC 2392) and Salmonella typhimurium (NRRL 4463) inoculated into Tekirdag meatballs was investigated. The meatball samples were inoculated with pathogens and irradiated at the absorbed doses of 1, 2.2, 3.2, 4.5 and 5.2 kGy. E. coli O157:H7 count in 1 kGy irradiated meatballs stored in the refrigerator for 7 days was detected to be 4 log cfu/g lower than the count in nonirradiated samples ( pcounts were decreased to 4 log cfu/g after being exposed to irradiation at a dose of 1 kGy. Although it was ineffective on elimination of S. typhimurium, irradiation at a dose of 3.2 kGy reduced E. coli O157:H7 and S. aureus counts under detectable values in the meatballs. However, none of the test organisms were detected in the samples after irradiation with 4.5 kGy doses.

  19. Antibiotic resistances in Listeria monocytogenes and Salmonella enterica isolated from foods with animal origin Resistencias a antibióticos en Listeria monocytogenes y Salmonella enterica aislados de alimentos de origen animal

    Directory of Open Access Journals (Sweden)

    Baltasar Balsalobre Hernández

    2004-12-01

    Full Text Available Extensive use of antibiotics in both human and animal health and in cattle production has generated resistant microorganisms to common antibiotics. Resistances spread caused by human and animal therapeutic is well known, but we know poorly frecuency of resistant bacteria in foods with animal origin and destinated to human consumers. In this paper, sensitivity to nineteen antibiotics was investigated in Listeria monocytogenes and Salmonella enterica strains isolated from foods with animal origin, including fresh meat, hamburgers, fresh sausages, boiled ham and new-laid chicken eggs. The plate diffusion method of Bauer-Kirby was used.Listeria monocytogenes strains showed a very high sensitivity to all antibiotics checked, with the exception of one strain tetracycline resistant. In contrast, Salmonella enterica showed a high frecuency of resistances, in special to tetracycline, streptomycin, nalidixic acid, ticarcillin, ampicillin and chloramphenicol. Moreover, multi-resistance was a common phenomenon. Twenty percent of S. enterica strains were resistant to four or more antibiotics. Frecuency of resistances was higher in 4,5,12:i:-, Hadar, Typhimurium and Virchow serotypes.In conclusion, Salmonella enterica strains isolated from foods with animal origin and destinated to human consumers are usually resistant to several antibiotics. The significance of this observation and its potential health risk must be investigated.El uso extensivo de antibióticos para la salud humana y animal así como para mejorar la producción ganadera ha generado un gran número de cepas microbianas resistentes a antibióticos de uso común. Es bien conocida la difusión de resistencias a través de la terapéutica humana y animal, pero desconocemos en qué medida los alimentos de origen animal destinados a consumo humano son portadores de resistencias.En este trabajo, se investigó la sensibilidad a diecinueve antibióticos de cepas de Listeria monocytogenes y Salmonella

  20. L. monocytogenes in a cheese processing facility: Learning from contamination scenarios over three years of sampling.

    Science.gov (United States)

    Rückerl, I; Muhterem-Uyar, M; Muri-Klinger, S; Wagner, K-H; Wagner, M; Stessl, B

    2014-10-17

    The aim of this study was to analyze the changing patterns of Listeria monocytogenes contamination in a cheese processing facility manufacturing a wide range of ready-to-eat products. Characterization of L. monocytogenes isolates included genotyping by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). Disinfectant-susceptibility tests and the assessment of L. monocytogenes survival in fresh cheese were also conducted. During the sampling period between 2010 and 2013, a total of 1284 environmental samples were investigated. Overall occurrence rates of Listeria spp. and L. monocytogenes were 21.9% and 19.5%, respectively. Identical L. monocytogenes genotypes were found in the food processing environment (FPE), raw materials and in products. Interventions after the sampling events changed contamination scenarios substantially. The high diversity of globally, widely distributed L. monocytogenes genotypes was reduced by identifying the major sources of contamination. Although susceptible to a broad range of disinfectants and cleaners, one dominant L. monocytogenes sequence type (ST) 5 could not be eradicated from drains and floors. Significantly, intense humidity and steam could be observed in all rooms and water residues were visible on floors due to increased cleaning strategies. This could explain the high L. monocytogenes contamination of the FPE (drains, shoes and floors) throughout the study (15.8%). The outcome of a challenge experiment in fresh cheese showed that L. monocytogenes could survive after 14days of storage at insufficient cooling temperatures (8 and 16°C). All efforts to reduce L. monocytogenes environmental contamination eventually led to a transition from dynamic to stable contamination scenarios. Consequently, implementation of systematic environmental monitoring via in-house systems should either aim for total avoidance of FPE colonization, or emphasize a first reduction of L. monocytogenes to sites where

  1. Oral Immunization with Recombinant Listeria monocytogenes Controls Virus Load after Vaginal Challenge with Feline Immunodeficiency Virus

    OpenAIRE

    Stevens, Rosemary; Howard, Kristina E.; Nordone, Sushila; Burkhard, MaryJo; Dean, Gregg A

    2004-01-01

    Recombinant Listeria monocytogenes has many attractive characteristics as a vaccine vector against human immunodeficiency virus (HIV). Wild-type and attenuated Listeria strains expressing HIV Gag have been shown to induce long-lived mucosal and systemic T-cell responses in mice. Using the feline immunodeficiency virus (FIV) model of HIV we evaluated recombinant L. monocytogenes in a challenge system. Five cats were immunized with recombinant L. monocytogenes that expresses the FIV Gag and del...

  2. Expression of Listeria monocytogenes key virulence genes during growth in liquid medium, on rocket and melon at 4, 10 and 30 °C.

    Science.gov (United States)

    Hadjilouka, Agni; Molfeta, Christina; Panagiotopoulou, Olga; Paramithiotis, Spiros; Mataragas, Marios; Drosinos, Eleftherios H

    2016-05-01

    The aim of the present study was to assess the expression of key virulence genes, during growth of a Listeria monocytogenes isolate in liquid medium, on melon and rocket at different temperatures and time. For that purpose, BHI broth, rocket and melon were inoculated at 7.0-7.5 log CFU mL(-1) or g(-1)and stored at 4, 10 and 30 °C. Sampling took place upon inoculation and after 0.5, 6 and 24 h of incubation. The RNA was stabilized and the expression of hly, plcA, plcB, sigB, inlA, inlB, inlC, inlJ, lmo2672 and lmo2470 was assessed by RT-qPCR. The results obtained were summarized into two observations; the first one referring to the interactive effect of incubation temperature and type of substrate and the second one to the effect of time on gene expression. Regarding the latter, nearly all genes were regulated upon inoculation and exhibited differential expression in the subsequent sampling times indicating the existence of additional regulatory mechanisms yet to be explored.

  3. Lineage specific recombination rates and microevolution in Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Nightingale Kendra K

    2008-10-01

    Full Text Available Abstract Background The bacterium Listeria monocytogenes is a saprotroph as well as an opportunistic human foodborne pathogen, which has previously been shown to consist of at least two widespread lineages (termed lineages I and II and an uncommon lineage (lineage III. While some L. monocytogenes strains show evidence for considerable diversification by homologous recombination, our understanding of the contribution of recombination to L. monocytogenes evolution is still limited. We therefore used STRUCTURE and ClonalFrame, two programs that model the effect of recombination, to make inferences about the population structure and different aspects of the recombination process in L. monocytogenes. Analyses were performed using sequences for seven loci (including the house-keeping genes gap, prs, purM and ribC, the stress response gene sigB, and the virulence genes actA and inlA for 195 L. monocytogenes isolates. Results Sequence analyses with ClonalFrame and the Sawyer's test showed that recombination is more prevalent in lineage II than lineage I and is most frequent in two house-keeping genes (ribC and purM and the two virulence genes (actA and inlA. The relative occurrence of recombination versus point mutation is about six times higher in lineage II than in lineage I, which causes a higher genetic variability in lineage II. Unlike lineage I, lineage II represents a genetically heterogeneous population with a relatively high proportion (30% average of genetic material imported from external sources. Phylograms, constructed with correcting for recombination, as well as Tajima's D data suggest that both lineages I and II have suffered a population bottleneck. Conclusion Our study shows that evolutionary lineages within a single bacterial species can differ considerably in the relative contributions of recombination to genetic diversification. Accounting for recombination in phylogenetic studies is critical, and new evolutionary models that

  4. Inflammasome-Mediated Inhibition of Listeria monocytogenes-Stimulated Immunity Is Independent of Myelomonocytic Function

    Science.gov (United States)

    Williams, Cassandra R.; Dustin, Michael L.; Sauer, John-Demian

    2013-01-01

    Activation of the Nlrc4 inflammasome results in the secretion of IL-1β and IL-18 through caspase-1 and induction of pyroptosis. L. monocytogenes engineered to activate Nlrc4 by expression of Legionella pneumophilia flagellin (L. monocytogenes L.p.FlaA) are less immunogenic for CD8+ T cell responses than wt L. monocytogenes. It is also known that IL-1β orchestrates recruitment of myelomonocytic cells (MMC), which have been shown to interfere with T cell-dendritic cells (DC) interactions in splenic white pulp (WP), limiting T cell priming and protective immunity. We have further analyzed the role of MMCs in the immunogenicity of L. monocytogenes L.p.FlaA. We confirmed that MMCs infiltrate the WP between 24–48 hours in response to wt L. monocytogenes infection and that depletion of MMCs enhances CD8+ T cell priming and protective memory. L. monocytogenes L.p.FlaA elicited accelerated recruitment of MMCs into the WP. While MMCs contribute to control of L. monocytogenes L.p.FlaA, MMC depletion did not increase immunogenicity of L.p.FlaA expressing strains. There was a significant decrease in L. monocytogenes L.p.FlaA in CD8α+ DCs independent of MMCs. These findings suggest that limiting inflammasome activation is important for bacterial accumulation in CD8α+ DCs, which are known to be critical for T cell response to L. monocytogenes. PMID:24349458

  5. Microbiological criteria for Listeria monocytogenes in foods under special consideration of risk assessment approaches

    DEFF Research Database (Denmark)

    Nørrung, Birgit

    2000-01-01

    This paper shortly summarizes data related to risk assessment of Listeria monocytogenes. From available data on risk assessment, it is concluded that the levels of L. monocytogenes consumed is an important factor affecting the incidence of listeriosis. Foods that do not support the growth of L....... monocytogenes are unlikely to be a source of listeriosis, whereas foods that support the growth to high levels, should be the target of risk management efforts. Based on current epidemiological information from several countries, a concentration of L. monocytogenes not exceeding 100/g of food at the time...

  6. Presence of Listeria monocytogenes in Mediterranean-Style Dry Fermented Sausages

    Directory of Open Access Journals (Sweden)

    Domenico Meloni

    2015-03-01

    Full Text Available The morphological, physiological and epidemiological features of L. monocytogenes, together with the severity of human listeriosis infections, make L. monocytogenes of particular concern for manufacturers of cold-stored “ready to eat” (RTE foods. L. monocytogenes has been isolated from a wide variety of RTE foods and is responsible for several outbreaks associated with the consumption of RTE meat, poultry, dairy, fish and vegetable products. Although L. monocytogenes is among the most frequently-detected pathogens in dry fermented sausages, these products could be included in the category of RTE products in which the growth of L. monocytogenes is not favored and have rarely been implicated in listeriosis outbreaks. However, L. monocytogenes is highly difficult to control in fermented sausage processing environments due to its high tolerance to low pH and high salt concentration. In many Mediterranean-style dry fermented sausages, an empirical application of the hurdle technology often occurs and the frequent detection of L. monocytogenes in these products at the end of ripening highlights the need for food business operators to properly apply hurdle technology and to control the contamination routes of L. monocytogenes in the processing plants. In the following, through an up-to-date review of (personal and un- published data, the main aspects of the presence of L. monocytogenes in Mediterranean-style dry fermented sausages will be discussed.

  7. Presence of Listeria monocytogenes in Mediterranean-Style Dry Fermented Sausages.

    Science.gov (United States)

    Meloni, Domenico

    2015-03-12

    The morphological, physiological and epidemiological features of L. monocytogenes, together with the severity of human listeriosis infections, make L. monocytogenes of particular concern for manufacturers of cold-stored "ready to eat" (RTE) foods. L. monocytogenes has been isolated from a wide variety of RTE foods and is responsible for several outbreaks associated with the consumption of RTE meat, poultry, dairy, fish and vegetable products. Although L. monocytogenes is among the most frequently-detected pathogens in dry fermented sausages, these products could be included in the category of RTE products in which the growth of L. monocytogenes is not favored and have rarely been implicated in listeriosis outbreaks. However, L. monocytogenes is highly difficult to control in fermented sausage processing environments due to its high tolerance to low pH and high salt concentration. In many Mediterranean-style dry fermented sausages, an empirical application of the hurdle technology often occurs and the frequent detection of L. monocytogenes in these products at the end of ripening highlights the need for food business operators to properly apply hurdle technology and to control the contamination routes of L. monocytogenes in the processing plants. In the following, through an up-to-date review of (personal and un-) published data, the main aspects of the presence of L. monocytogenes in Mediterranean-style dry fermented sausages will be discussed.

  8. Spontaneous bacterial peritonitis due to Listeria monocytogenes: importance of enrichment culture.

    Science.gov (United States)

    Jayasinghe, Saroj; Connor, Martin; Donaldson, Shona; Austin, Hannah; Foster, Adele

    2010-09-01

    A case of Listeria monocytogenes induced spontaneous bacterial peritonitis (SBP) is reported in a patient with primary biliary cirrhosis. It is an indolent illness and may not show a neutrophil reaction in peritoneal fluid. Enrichment broth was required to isolate L monocytogenes in the patient. This is not routinely used in the UK and therefore isolates may be missed. L monocytogenes remains sensitive to ampicillin, penicillin and gentamicin, but is resistant to cephalosporin antibiotics. The rising incidence of listeriosis in the population suggests that the incidence of SBP from L monocytogenes is likely to increase.

  9. Inflammasome-mediated inhibition of Listeria monocytogenes-stimulated immunity is independent of myelomonocytic function.

    Directory of Open Access Journals (Sweden)

    Cassandra R Williams

    Full Text Available Activation of the Nlrc4 inflammasome results in the secretion of IL-1β and IL-18 through caspase-1 and induction of pyroptosis. L. monocytogenes engineered to activate Nlrc4 by expression of Legionella pneumophilia flagellin (L. monocytogenes L.p.FlaA are less immunogenic for CD8(+ T cell responses than wt L. monocytogenes. It is also known that IL-1β orchestrates recruitment of myelomonocytic cells (MMC, which have been shown to interfere with T cell-dendritic cells (DC interactions in splenic white pulp (WP, limiting T cell priming and protective immunity. We have further analyzed the role of MMCs in the immunogenicity of L. monocytogenes L.p.FlaA. We confirmed that MMCs infiltrate the WP between 24-48 hours in response to wt L. monocytogenes infection and that depletion of MMCs enhances CD8(+ T cell priming and protective memory. L. monocytogenes L.p.FlaA elicited accelerated recruitment of MMCs into the WP. While MMCs contribute to control of L. monocytogenes L.p.FlaA, MMC depletion did not increase immunogenicity of L.p.FlaA expressing strains. There was a significant decrease in L. monocytogenes L.p.FlaA in CD8α(+ DCs independent of MMCs. These findings suggest that limiting inflammasome activation is important for bacterial accumulation in CD8α(+ DCs, which are known to be critical for T cell response to L. monocytogenes.

  10. Metabiotic effects of Fusarium spp. on Escherichia coli O157:H7 and Listeria monocytogenes on raw portioned tomatoes.

    Science.gov (United States)

    Bevilacqua, Antonio; Cibelli, Francesca; Cardillo, Daniela; Altieri, Clelia; Sinigaglia, Milena

    2008-07-01

    The metabiotic effects of Fusarium proliferatum, F. avenaceum, and F. oxysporum on Escherichia coli O157:H7 and Listeria monocytogenes in fresh tomatoes were investigated. Tomatoes were preinoculated with the molds and incubated at 15 degrees C for 7 days; then they were inoculated separately with the pathogens, packaged in air and modified atmosphere (5% O2, 30% CO2, and 65% N2), and stored at 4, 8, and 12 degrees C for 9 days. The cell loads of pathogens and lactic acid bacteria and the pH were evaluated periodically. The data were modeled through some different mathematical models to assess the shoulder length, i.e., the time before the beginning of the exponential death phase, the 1-log reduction time (s), and the pathogen death time (deltastand). The preinoculation of tomatoes with the molds enhanced the survival of E. coli O157:H7 by prolonging shoulder length and 8 parameters; this effect, however, was not observed for L. monocytogenes. pH values did not undergo significant changes within the storage time, and the lactic acid bacteria increased from 5 to 7 log CFU/g, without significant differences among the storage temperatures or the packaging atmospheres. The results of this research showed that the use of fresh tomatoes colonized by fusaria (even if the contamination is not visible) could increase significantly the risk of outbreaks due to some pathogens that could be on the surface of fruits and vegetables as a result of cross-contamination at home or incorrect postharvest operations.

  11. Effect of biofilm dryness on the transfer of Listeria monocytogenes biofilms grown on stainless steel to bologna and hard salami.

    Science.gov (United States)

    Rodríguez, Andrés; Autio, Wesley R; McLandsborough, Lynne A

    2007-11-01

    Listeria monocytogenes continues to be a major cause of class I food recalls in the United States. Very little is known about its transfer and cross-contamination in processing scenarios. The objective of this study was to evaluate the effect of hydration level on L. monocytogenes biofilms grown on stainless steel and its effect on the biofilm transfer to foods. Biofilms were grown on stainless steel in diluted tryptic soy broth 1:20 for 48 h at 32 degrees C. After this, biofilms were equilibrated over saturated salt solutions at 20 degrees C for 24 h (94, 75, 58, and 33% relative humidity; % RH) prior to transferring. Transfer experiments were conducted from inoculated stainless steel to bologna and hard salami at a constant pressure (45 kPa) and time (30 s) with a universal testing machine. The experiment was designed with a factorial design 4 x 2 (biofilms equilibrated at 4% RH and two foods) and duplicated every day, and the whole experiment was repeated nine times. The results were analyzed with an analysis of variance by SAS Statistical Analysis Software. Our results showed that more bacteria were transferred to bologna (mean efficiency of transfer [EOT] = 3.0) than to hard salami (mean EOT = 0.35, P biofilms became drier, the transfer of Listeria from stainless steel to both foods increased (P biofilm for bologna and hard salami, respectively. This study may be an indication that as biofilms were dried, the cell-cell and cell-surface interactions became weaker, and bacterial transfer increased. This phenomenon was enhanced in foods containing higher water activity levels. We hypothesize that this increased in transfer was due to the presence of capillary forces in the food.

  12. Crystal structure of 4,5-bis-(3,4,5-tri-meth-oxy-phen-yl)-2H-1,2,3-triazole methanol monosolvate.

    Science.gov (United States)

    Madadi, Nikhil Reddy; Penthala, Narsimha Reddy; Bommagani, Shobanbabu; Parkin, Sean; Crooks, Peter A

    2014-10-01

    The title compound, C20H23N3O6·CH3OH, was synthesized by [3 + 2] cyclo-addition of (Z)-2,3-bis-(3,4,5-tri-meth-oxy-phen-yl)acrylo-nitrile with sodium azide and ammonium chloride in DMF/water. The central nitro-gen of the triazole ring is protonated. The dihedral angles between the triazole ring and the 3,4,5-tri-meth-oxy-phenyl ring planes are 34.31 (4) and 45.03 (5)°, while that between the 3,4,5-tri-meth-oxy-phenyl rings is 51.87 (5)°. In the crystal, the mol-ecules, along with two methanol solvent mol-ecules are linked into an R (4) 4(10) centrosymmetric dimer by N-H⋯O and O-H⋯N hydrogen bonds.

  13. Effects of genotype x bradyrhizobium inoculation or x fertilizer n ...

    African Journals Online (AJOL)

    Genotype x inoculation interaction was significant only for protein and oil content in one year. ... seed composition, or other agronoi:nic traits including plant .... used to compare expected genetic of inoculation on maturity, p;ant height, a;:d yick!

  14. Silage Inoculant Effects on In Vitro Rumen Fermentation

    Science.gov (United States)

    Four inoculants, B (Lactobacillus plantarum and Enterococcus faecium), C (Lactobacillus plantarum), D (Lactobacillus pentosus), E (Lactococcus lactis), were compared with an uninoculated treatment (A) on alfalfa (38% DM, AS), corn (36% DM, CS), and brown midrib corn (33% DM, BMR) silages. All inocul...

  15. Lactating cow response to lucerne silage inoculated with Lactobacillus plantarum

    Science.gov (United States)

    It is unclear why bacterial silage inoculants improve milk production in lactating dairy cattle. However, recent in vitro results suggest that inoculated silage effects on milk production may be tied to greater production of rumen microorganisms. Our objective was to determine if alfalfa silage trea...

  16. Coordination chemistry and applications of versatile 4,5-diazafluorene derivatives.

    Science.gov (United States)

    Annibale, Vincent T; Song, Datong

    2016-01-01

    This perspective review will examine the coordination chemistry and applications of metal complexes of 4,5-diazafluorene derivatives. The versatile derivatives of 4,5-diazafluorene can serve multiple roles, and display a number of coordination modes. The ambidentate derivatives with multiple coordination sites can allow for the syntheses of coordination polymers, multimetallic, and macrocyclic complexes. In addition, certain 4,5-diazafluorene derivatives can serve as spectator ligands to support reactivity at the metal centre, or as reactive actor ligands engaging in atypical reactivity patterns. The applications of metal complexes of 4,5-diazafluorene derivatives in catalysis, photochemistry and photophysics, as well as in bioinorganic chemistry are also surveyed.

  17. Determination of inositol 1,4,5-trisphosphate levels in Dictyostelium by isotope dilution assay

    Energy Technology Data Exchange (ETDEWEB)

    Van Haastert, P.J.

    1989-02-15

    A commercial isotope dilution assay was used for the determination of Ins(1,4,5)P3 levels in the microorganism Dictyostelium discoideum. Cross-reactivity in the assay was detected with extracts from cells and the medium. The compound which induced this cross-reactivity was tentatively identified as Ins(1,4,5)P3 by (i) codegradation with authentic (/sup 32/P)Ins(1,4,5)P3 by three specific Ins(1,4,5)P3 phosphatases, and (ii) co-chromatography with authentic (/sup 32/P)Ins(1,4,5)P3 on HPLC columns. The cellular concentration was estimated as 165 +/- 42 pmol/10(8) cells, yielding a mean intracellular Ins(1,4,5)P3 concentration of 3.3 microM. Dictyostelium cells secrete large amounts of Ins(1,4,5)P3 at a rate of about 10% of the cellular content per minute, yielding about 0.13 microM extracellular Ins(1,4,5)P3 after 15 min in a suspension of 10(8) cells/ml. The chemoattractant cAMP induced a transient increase of the Ins(1,4,5)P3 concentration; the data suggest an intracacellular rise from 3.3 to 5.5 microM with a maximum at 6 s after stimulation.

  18. Effects of bilimbi (Averrhoa bilimbi L.) and tamarind (Tamarindus indica L.) juice on Listeria monocytogenes Scott A and Salmonella Typhimurium ATCC 14028 and the sensory properties of raw shrimps.

    Science.gov (United States)

    Norhana, M N Wan; Azman, Mohd Nor A; Poole, Susan E; Deeth, Hilton C; Dykes, Gary A

    2009-11-30

    The potential of using juice of bilimbi (Averrhoa bilimbi L.) and tamarind (Tamarindus indica L.) to reduce Listeria monocytogenes Scott A and Salmonella Typhimurium ATCC 14028 populations on raw shrimps after washing and during storage (4 degrees C) was investigated. The uninoculated raw shrimps and those inoculated with approximately 9 log cfu/ml of L. monocytogenes Scott A and S. Typhimurium ATCC 14028 were washed (dipped or rubbed) in distilled water (SDW) (control), bilimbi or tamarind juice at 1:4 (w/v) concentrations for 10 and 5 min. Naturally occurring aerobic bacteria (APC), L. monocytogenes Scott A and S. Typhimurium ATCC 14028 counts, pH values and sensory analysis of washed shrimps were determined immediately after washing (day 0), and on days 3 and 7 of storage. Compared to SDW, bilimbi and tamarind juice significantly (p0.05) throughout the storage except for odour (plemony smell was noticed in bilimbi- and tamarind-washed shrimps and not in control shrimps.

  19. Inactivation of Escherichia coli, Listeria monocytogenes, and Salmonella Enteritidis by Cymbopogon citratus D.C. Stapf. Essential Oil in Pineapple Juice.

    Science.gov (United States)

    Leite, Caroline Junqueira Barcellos; de Sousa, Jossana Pereira; Medeiros, José Alberto da Costa; da Conceição, Maria Lúcia; dos Santos Falcão-Silva, Vivyanne; de Souza, Evandro Leite

    2016-02-01

    In the present study, the efficacy of Cymbopogon citratus D.C. Stapf. essential oil (CCEO) to provoke a 5-log CFU/ml (5-log) inactivation in a mixed composite of Escherichia coli, Listeria monocytogenes, and Salmonella enterica serovar Enteritidis in pineapple (Ananas comosus (L.) Merril) juice (4°C) was assessed. Moreover, the effects of CCEO on the physicochemical and sensory quality parameters of pineapple juice were evaluated. The MIC of CCEO was 5 μl/ml against the composite mix examined. For L. monocytogenes and E. coli inoculated in juice containing CCEO (5, 2.5, and 1.25 μl/ml), a ≥5-log reduction was detected after 15 min of exposure. This same result was obtained for Salmonella Enteritidis incubated alone in pineapple juice containing CCEO at 5 and 2.5 μl/ml. Overall, Salmonella Enteritidis was the most tolerant and L. monocytogenes was the most sensitive to CCEO. The physicochemical properties (pH, titratable acidic [citric acid per 100 g], and soluble solids) of pineapple juice containing CCEO (2.5 and 1.25 μl/ml) were maintained. Juice containing CCEO (2.5 and 1.25 μl/ml) exhibited similar scores for odor, appearance, and viscosity compared with juice without CCEO. However, unsatisfactory changes in taste and aftertaste were observed in juices containing CCEO. These results suggest that CCEO could be used as an alternative antimicrobial compound to ensure the safety of pineapple juice, although CCEO at the tested concentrations negatively impacted its taste. Therefore, further studies are needed to determine the balance between microbial safety and taste acceptability of pineapple juice containing CCEO.

  20. Comparison of desiccation tolerance among Listeria monocytogenes, Escherichia coli O157:H7, Salmonella enterica, and Cronobacter sakazakii in powdered infant formula.

    Science.gov (United States)

    Koseki, Shigenobu; Nakamura, Nobutaka; Shiina, Takeo

    2015-01-01

    Bacterial pathogens such as Listeria monocytogenes, Escherichia coli O157:H7, Salmonella enterica, and Cronobacter sakazakii have demonstrated long-term survival in/on dry or low-water activity (aw) foods. However, there have been few comparative studies on the desiccation tolerance among these bacterial pathogens separately in a same food matrix. In the present study, the survival kinetics of the four bacterial pathogens separately inoculated onto powdered infant formula as a model low-aw food was compared during storage at 5, 22, and 35°C. No significant differences in the survival kinetics between E. coli O157:H7 and L. monocytogenes were observed. Salmonella showed significantly higher desiccation tolerance than these pathogens, and C. sakazakii demonstrated significantly higher desiccation tolerance than all other three bacteria studied. Thus, the desiccation tolerance was represented as C. sakazakii > Salmonella > E. coli O157:H7 = L. monocytogenes. The survival kinetics of each bacterium was mathematically analyzed, and the observed kinetics was successfully described using the Weibull model. To evaluate the variability of the inactivation kinetics of the tested bacterial pathogens, the Monte Carlo simulation was performed using assumed probability distribution of the estimated fitted parameters. The simulation results showed that the storage temperature significantly influenced survival of each bacterium under the dry environment, where the bacterial inactivation became faster with increasing storage temperature. Furthermore, the fitted rate and shape parameters of the Weibull model were successfully modelled as a function of temperature. The numerical simulation of the bacterial inactivation was realized using the functions of the parameters under arbitrary fluctuating temperature conditions.

  1. Structural studies of transition metal complexes with 4,5-bis(2-pyridylmethylsulfanyl)-4',5'-ethylenedithiotetrathiafulvalene: probing their potential for the construction of multifunctional molecular assemblies.

    Science.gov (United States)

    Liu, Shi-Xia; Dolder, Stefan; Franz, Patrick; Neels, Antonia; Stoeckli-Evans, Helen; Decurtins, Silvio

    2003-08-11

    Three divalent transition metal complexes of 4,5-bis(2-pyridylmethylsulfanyl)-4',5'-ethylenedithiotetrathiafulvalene have been prepared and crystallographically characterized. The isostructural Co(II) and the Ni(II) complexes show octahedral geometries around the metal ions with the coordination sites occupied by the pyridyl nitrogen atoms and the thioether sulfur atoms of the ligand and cis coordination of the halide ions. Cyclic voltammetry reveals that the complexation leads to a small anodic shift in the first oxidation potential of the TTF system.

  2. Directed solid-phase synthesis of trisubstituted imidazo[4,5-c]pyridines and imidazo[4,5-b]pyridines.

    Science.gov (United States)

    Lemrová, Barbora; Smyslová, Petra; Popa, Igor; Oždian, Tomáš; Zajdel, Pawel; Soural, Miroslav

    2014-10-13

    An efficient method is described for the solid-supported synthesis of imidazo[4,5-b]pyridines and imidazo[4,5-c]pyridines from 2,4-dichloro-3-nitropyridine. The key pyridine building block was reacted with polymer-supported amines, followed by replacement of the second chlorine with amines, nitro group reduction, and imidazole ring closure with aldehydes. Depending on the combination of polymer-supported and solution-phase reagents, the strategy allowed for the simple preparation of the target trisubstituted derivatives with variable positioning of the pyridine nitrogen atom. Additionally, after a slight modification of the method, the preparation of strictly isomeric imidazopyridines was possible.

  3. Listeria monocytogenes: survival and adaptation in the gastrointestinal tract

    Directory of Open Access Journals (Sweden)

    Cormac G.M. Gahan

    2014-02-01

    Full Text Available The foodborne pathogen Listeria monocytogenes has the capacity to survive and grow in a diverse range of natural environments. The transition from a food environment to the gastrointestinal tract begins a process of adaptation that may culminate in invasive systemic disease. Here we describe recent advances in our understanding of how L. monocytogenes adapts to the gastrointestinal environment prior to initiating systemic infection. We will discuss mechanisms used by the pathogen to survive encounters with acidic environments (which include the glutamate decarboxylase and arginine deiminase systems, and those which enable the organism to cope with bile acids (including bile salt hydrolase and competition with the resident microbiota. An increased understanding of how the pathogen survives in this environment is likely to inform the future design of novel prophylactic approaches that exploit specific pharmabiotics; including probiotics, prebiotics or phages.

  4. Keberadaan Bakteri Listeria monocytogenes pada Keju Gouda Produksi Lokal dan Impor (PRESENCE OF LISTERIA MONOCYTOGENES IN LOCAL AND IMPORTED GOUDA CHEESES

    Directory of Open Access Journals (Sweden)

    Debby Fadhilah Pazra

    2014-08-01

    Full Text Available Listeria monocytogenes is included in the foodborne pathogen, which has been associated with severaloutbreaks of human listeriosis especially in high risk groups. Listeria monocytogenes could be found inGouda cheeses because of poor hygienic and sanitation practices. In addition, this bacteria could surviveduring the making of cheese and cheese ripening process. The purpose of this study was to identify thepresence of L. monocytogenes in local and imported Gouda cheeses and how the safety level of the Goudacheese against contamination of L. monocytogenes. This study used the conventional method in accordancewith the Bacteriological Analytical Manual, US Food and Drug Administration and Bergey’s Manual ofDeterminative Bacteriology to detect the presence of L. monocytogenes at 15 samples of local Gouda cheeseand 15 samples of imported Gouda cheese sold in supermarkets in Jakarta and Bogor. The results of thisstudy showed that was not found L. monocytogenes in local and imported Gouda cheese. It could be concludedthat is Gouda cheese relatively safe from L. monocytogenes and meets Indonesian National Standard.

  5. Transcriptional and phenotypic responses of Listeria monocytogenes to chlorine dioxide.

    Science.gov (United States)

    Pleitner, Aaron M; Trinetta, Valentina; Morgan, Mark T; Linton, Richard L; Oliver, Haley F

    2014-05-01

    Significant food-borne disease outbreaks have occurred from consumption of ready-to-eat foods, including produce, contaminated with Listeria monocytogenes. Challenging food matrices (e.g., cantaloupe, sprouts) with limited processing steps postharvest to reduce pathogen loads have underscored a need for new mitigation strategies. Chlorine dioxide (ClO2) is increasingly being used in produce and other food systems to reduce food-borne pathogen levels. The goal of this study was to characterize the transcriptional response and survival of L. monocytogenes 10403S exposed to ClO2. The transcriptional profile of log-phase cells exposed to 300 mg/liter ClO2 for 15 min was defined by whole-genome microarray. A total of 340 genes were significantly differentially expressed. Among the differentially expressed genes, 223 were upregulated (fold change ≥ 1.5; adjusted P value < 0.05) in role categories responsible for protein fate, cellular processes, and energy metabolism. There were 113 and 16 genes differentially expressed belonging to regulatory networks of σ(B) and CtsR, respectively. We assessed L. monocytogenes 10403S survival after exposure to 100, 300, and 500 mg/liter aqueous ClO2 in brain heart infusion (BHI) broth; there was a significant difference between cells exposed to 500 mg/liter ClO2 and those exposed to all other conditions over time (P value < 0.05). Isogenic ΔsigB and ΔctsR mutants exposed to 300 mg/liter ClO2 were more sensitive to ClO2 than the wild type under the same conditions. These results provide an initial insight into the mechanisms that L. monocytogenes employs to survive sublethal ClO2 and further our understanding of the inactivation mechanisms of this increasingly used sanitizer.

  6. How Listeria monocytogenes organizes its surface for virulence

    Directory of Open Access Journals (Sweden)

    Filipe eCarvalho

    2014-04-01

    Full Text Available Listeria monocytogenes is a Gram-positive pathogen responsible for the manifestation of human listeriosis, an opportunistic foodborne disease with an associated high mortality rate. The key to the pathogenesis of listeriosis is the capacity of this bacterium to trigger its internalization by non-phagocytic cells and to survive and even replicate within phagocytes. The arsenal of virulence proteins deployed by L. monocytogenes to successfully promote the invasion and infection of host cells has been progressively unveiled over the past decades. A large majority of them are located at the cell envelope, which provides an interface for the establishment of close interactions between these bacterial factors and their host targets. Along the multistep pathways carrying these virulence proteins from the inner side of the cytoplasmic membrane to their cell envelope destination, a multiplicity of auxiliary proteins must act on the immature polypeptides to ensure that they not only maturate into fully functional effectors but also are placed or guided to their correct position in the bacterial surface. As the major scaffold for surface proteins, the cell wall and its metabolism are critical elements in listerial virulence. Conversely, the crucial physical support and protection provided by this structure make it an ideal target for the host immune system. Therefore, mechanisms involving fine modifications of cell envelope components are activated by L. monocytogenes to render it less recognizable by the innate immunity sensors or more resistant to the activity of antimicrobial effectors. This review provides a state-of-the-art compilation of the mechanisms used by L. monocytogenes to organize its surface for virulence, with special focus on those proteins that work behind the frontline, either supporting virulence effectors or ensuring the survival of the bacterium within its host.

  7. How Listeria monocytogenes organizes its surface for virulence

    Science.gov (United States)

    Carvalho, Filipe; Sousa, Sandra; Cabanes, Didier

    2014-01-01

    Listeria monocytogenes is a Gram-positive pathogen responsible for the manifestation of human listeriosis, an opportunistic foodborne disease with an associated high mortality rate. The key to the pathogenesis of listeriosis is the capacity of this bacterium to trigger its internalization by non-phagocytic cells and to survive and even replicate within phagocytes. The arsenal of virulence proteins deployed by L. monocytogenes to successfully promote the invasion and infection of host cells has been progressively unveiled over the past decades. A large majority of them is located at the cell envelope, which provides an interface for the establishment of close interactions between these bacterial factors and their host targets. Along the multistep pathways carrying these virulence proteins from the inner side of the cytoplasmic membrane to their cell envelope destination, a multiplicity of auxiliary proteins must act on the immature polypeptides to ensure that they not only maturate into fully functional effectors but also are placed or guided to their correct position in the bacterial surface. As the major scaffold for surface proteins, the cell wall and its metabolism are critical elements in listerial virulence. Conversely, the crucial physical support and protection provided by this structure make it an ideal target for the host immune system. Therefore, mechanisms involving fine modifications of cell envelope components are activated by L. monocytogenes to render it less recognizable by the innate immunity sensors or more resistant to the activity of antimicrobial effectors. This review provides a state-of-the-art compilation of the mechanisms used by L. monocytogenes to organize its surface for virulence, with special focus on those proteins that work “behind the frontline”, either supporting virulence effectors or ensuring the survival of the bacterium within its host. PMID:24809022

  8. Targeting of the central nervous system by Listeria monocytogenes.

    OpenAIRE

    Disson, Olivier; Lecuit, Marc

    2012-01-01

    Among bacteria that reach the central nervous system (CNS), Listeria monocytogenes (Lm) is one of deadliest, in human and ruminant. This facultative intracellular bacterium has the particularity to induce meningitis, meningoencephalitis and rhombencephalitis. Mechanisms by which Lm accesses the CNS remain poorly understood, but two major routes of infection have been proposed, based on clinical, in vitro and in vivo observations. A retrograde neural route is likely to occur in ruminants upon ...

  9. [Evaluation of the effect of Lactobacillus rhamnosus probiotic culture added to yogurt over Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enteritidis populations].

    Science.gov (United States)

    Calderón, Oscar; Padilla, Carolina; Chaves, Carolina; Villalobos, Laura; Arias, María Laura

    2007-03-01

    The effect of different types of probiotics present in yogurt over known populations of Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enteritidis was evaluated. The three types of yogurt used were: without added probiotics, with added probiotics (Lactobacillus casei CRL_431 and L. acidophilus CRL_730 CHR HANSEN) and another one with the same probiotics mentioned above and Lactobacillus rhamnosus (LR-35) culture. About 10(9) CFU/ mL of each potentially pathogenic bacteria was added to each type of yogurt tested, and kept in refrigeration at 4 degrees C during its shelf life, about 30 days. Bacterial count was done the initial day and every four days. Results obtained show that there is a difference in the inhibition between yogurts without added probiotics and the commercial yogurt with added probiotics; there is a clear inhibitory effect of the last one over S. aureus, E. coli O157:H7 and Listeria monocytogenes. The yogurt with added probiotics and L. rhamnosus did not show any additional inhibitory effect over the bacteria tested when compared with the yogurt with added probiotics. S. enteritidis could not be evaluated because it was not detectable in any yogurt samples evaluated four days after its inoculation. This study confirms the antagonic effect of probiotic cultures over potentially pathogenic bacteria for human beings and animals that may be present in food. Nevertheless, the use of L. rhamnosus did not produce any additional inhibitory effect.

  10. Changes in ruminal bacterial community composition following feeding of alfalfa silage inoculated with a commercial silage inoculant

    Science.gov (United States)

    Some silage inoculants promote an increase in milk production, possibly through altering the rumen microflora. In this study, dairy cows fed alfalfa silage treated with the inoculant, Lactobacillus plantarum MTD/1 (LPS), were compared to cows fed untreated silage (Ctrl) with the objectives: 1) to de...

  11. Towards a systemic understanding of Listeria monocytogenes metabolism during infection

    Directory of Open Access Journals (Sweden)

    Thilo M Fuchs

    2012-02-01

    Full Text Available Listeria monocytogenes is a foodborne human pathogen that can cause invasive infection in susceptible animals and humans. For proliferation within hosts, this facultative intracellular pathogen uses a reservoir of specific metabolic pathways, transporter and enzymatic functions whose expression requires the coordinated activity of a complex regulatory network. The highly adapted metabolism of L. monocytogenes strongly depends on the nutrient composition of various milieus encountered during infection. Transcriptomic and proteomic studies revealed the spatial-temporal dynamic of gene expression of this pathogen during replication within cultured cells or in vivo. Metabolic clues are the utilization of unusual C2- and C3-bodies, the metabolism of pyruvate, thiamine availability, the uptake of peptides, the acquisition or biosynthesis of certain amino acids, and the degradation of glucose-phosphate via the pentose phosphate pathway. These examples illustrate the interference of in vivo conditions with energy, carbon and nitrogen metabolism, thus affecting listerial growth. The exploitation, analysis and modelling of the available data sets served as a first attempt to a systemic understanding of listerial metabolism during infection. L. monocytogenes might serve as a model organism for systems biology of a Gram-positive, facultative intracellular bacterium.

  12. Assessment of Listeria sp. Interference Using a Molecular Assay To Detect Listeria monocytogenes in Food.

    Science.gov (United States)

    Zittermann, Sandra I; Stanghini, Brenda; See, Ryan Soo; Melano, Roberto G; Boleszczuk, Peter; Murphy, Allana; Maki, Anne; Mallo, Gustavo V

    2016-01-01

    Detection of Listeria monocytogenes in food is currently based on enrichment methods. When L. monocytogenes is present with other Listeria species in food, the species compete during the enrichment process. Overgrowth competition of the nonpathogenic Listeria species might result in false-negative results obtained with the current reference methods. This potential issue was noted when 50 food samples artificially spiked with L. monocytogenes were tested with a real-time PCR assay and Canada's current reference method, MFHPB-30. Eleven of the samples studied were from foods naturally contaminated with Listeria species other than those used for spiking. The real-time PCR assay detected L. monocytogenes in all 11 of these samples; however, only 6 of these samples were positive by the MFHPB-30 method. To determine whether L. monocytogenes detection can be affected by other species of the same genus due to competition, an L. monocytogenes strain and a Listeria innocua strain with a faster rate of growth in the enrichment broth were artificially coinoculated at different ratios into ground pork meat samples and cultured according to the MFHPB-30 method. L. monocytogenes was detected only by the MFHPB-30 method when L. monocytogenes/L. innocua ratios were 6.0 or higher. In contrast, using the same enrichments, the real-time PCR assay detected L. monocytogenes at ratios as low as 0.6. Taken together, these findings support the hypothesis that L. monocytogenes can be outcompeted by L. innocua during the MFHPB-30 enrichment phase. However, more reliable detection of L. monocytogenes in this situation can be achieved by a PCR-based method mainly because of its sensitivity.

  13. Recombinant Probiotic Expressing Listeria Adhesion Protein Attenuates Listeria monocytogenes Virulence In Vitro

    Science.gov (United States)

    Koo, Ok Kyung; Amalaradjou, Mary Anne Roshni; Bhunia, Arun K.

    2012-01-01

    Background Listeria monocytogenes, an intracellular foodborne pathogen, infects immunocompromised hosts. The primary route of transmission is through contaminated food. In the gastrointestinal tract, it traverses the epithelial barrier through intracellular or paracellular routes. Strategies to prevent L. monocytogenes entry can potentially minimize infection in high-risk populations. Listeria adhesion protein (LAP) aids L. monocytogenes in crossing epithelial barriers via the paracellular route. The use of recombinant probiotic bacteria expressing LAP would aid targeted clearance of Listeria from the gut and protect high-risk populations from infection. Methodology/Principal Findings The objective was to investigate the ability of probiotic bacteria or LAP-expressing recombinant probiotic Lactobacillus paracasei (LbpLAP) to prevent L. monocytogenes adhesion, invasion, and transwell-based transepithelial translocation in a Caco-2 cell culture model. Several wild type probiotic bacteria showed strong adhesion to Caco-2 cells but none effectively prevented L. monocytogenes infection. Pre-exposure to LbpLAP for 1, 4, 15, or 24 h significantly (Pmonocytogenes in Caco-2 cells, whereas pre-exposure to parental Lb. paracasei had no significant effect. Similarly, LbpLAP pre-exposure reduced L. monocytogenes translocation by as much as 46% after 24 h. LbpLAP also prevented L. monocytogenes-mediated cell damage and compromise of tight junction integrity. Furthermore, LbpLAP cells reduced L. monocytogenes-mediated cell cytotoxicity by 99.8% after 1 h and 79% after 24 h. Conclusions/Significance Wild type probiotic bacteria were unable to prevent L. monocytogenes infection in vitro. In contrast, LbpLAP blocked adhesion, invasion, and translocation of L. monocytogenes by interacting with host cell receptor Hsp60, thereby protecting cells from infection. These data show promise for the use of recombinant probiotics in preventing L. monocytogenes infection in high

  14. Genetic selection and DNA sequences of 4.5S RNA homologs

    DEFF Research Database (Denmark)

    Brown, S; Thon, G; Tolentino, E

    1989-01-01

    A general strategy for cloning the functional homologs of an Escherichia coli gene was used to clone homologs of 4.5S RNA from other bacteria. The genes encoding these homologs were selected by their ability to complement a deletion of the gene for 4.5S RNA. DNA sequences of the regions encoding...

  15. 3-Methyl-4,5,6,7-tetrahydro-1-benzothiophene-2-carboxylic Acid

    Directory of Open Access Journals (Sweden)

    Rajendiran Nagappan

    2010-01-01

    Full Text Available 3-Methyl-4,5,6,7-tetrahydro-1-benzothiophene-2-carboxylic acid was synthesized chemoselectively from 3-formyl-4,5,6,7-tetrahydro-1-benzothiophene-2-carboxylic acid, using Et3SiH/I2 as a reducing agent. The title compound was characterized by IR, 1H NMR, 13C NMR and LCMS.

  16. Early Number and Arithmetic Performance of Ecuadorian 4-5-Year-Olds

    Science.gov (United States)

    Bojorque, Gina; Torbeyns, Joke; Moscoso, Jheni; Van Nijlen, Daniël; Verschaffel, Lieven

    2015-01-01

    This study aimed at (a) constructing a reliable and valid test to assess Ecuadorian 4-5-year olds' number and arithmetic skills; (b) providing empirical data on Ecuadorian 4-5-year olds' number and arithmetic skills; and (c) confronting these children's actual performances with the performances expected by national experts in this domain. We…

  17. Unprecedentedly mild direct Pd-catalyzed arylation of oxazolo[4,5-b]pyridine

    DEFF Research Database (Denmark)

    Zhuravlev, Fedor

    2006-01-01

    Pd-catalyzed C-2 arylation of oxazolo[4,5-b]pyridine proceeds efficiently at 30 degrees C and tolerates a variety of aryl halides, including derivatized amino acids for which no racemization was observed during the reaction. Experimental evidence for facile deprotonation of oxazolo[4,5-b]pyridine...

  18. Analysis of data mining classification by comparison of C4.5 and ID algorithms

    Science.gov (United States)

    Sudrajat, R.; Irianingsih, I.; Krisnawan, D.

    2017-01-01

    The rapid development of information technology, triggered by the intensive use of information technology. For example, data mining widely used in investment. Many techniques that can be used assisting in investment, the method that used for classification is decision tree. Decision tree has a variety of algorithms, such as C4.5 and ID3. Both algorithms can generate different models for similar data sets and different accuracy. C4.5 and ID3 algorithms with discrete data provide accuracy are 87.16% and 99.83% and C4.5 algorithm with numerical data is 89.69%. C4.5 and ID3 algorithms with discrete data provides 520 and 598 customers and C4.5 algorithm with numerical data is 546 customers. From the analysis of the both algorithm it can classified quite well because error rate less than 15%.

  19. Phenanthro[4,5-fgh]quinoxaline-Fused Subphthalocyanines: Synthesis, Structure, and Spectroscopic Characterization.

    Science.gov (United States)

    Pan, Houhe; Liu, Wenbo; Wang, Chiming; Wang, Kang; Jiang, Jianzhuang

    2016-07-01

    A series of four phenanthro[4,5-fgh]quinoxaline-fused subphthalocyanine derivatives 0-3 containing zero, one, two, and three phenanthro[4,5-fgh]quinoxaline moieties, respectively, were isolated from the mixed cyclotrimerization reaction of 2,9-di-tert-butylphenanthro[4,5-fgh]quinoxaline-5,6-dicarbonitrile with 4,5-bis(2,6-diisopropylphenoxy)phthalonitrile and characterized by a series of spectroscopic methods including MALDI-TOF mass, (1) H NMR, electronic absorption, magnetic circular dichroism (MCD), and fluorescence spectroscopy. The molecular structures for the compounds 0 and 2 were clearly revealed on the basis of single-crystal X-ray diffraction analysis. Their electrochemical properties were also studied by cyclic voltammetry. In particular, theoretical calculations in combination with the electronic absorption and electrochemical analyses revealed the significant influence of the fused-phenanthro[4,5-fgh]quinoxaline units on the electronic structures.

  20. [Raoultella planticola, a new strain degrading 2,4,5-trichlorophenoxyacetic acid].

    Science.gov (United States)

    Zharikova, N V; Markusheva, T V; Galkin, E G; Korobov, V V; Zhurenko, E Iu; Sitdikova, L R; Kolganova, T V; Kuznetsov, B B; Turova, T P

    2006-01-01

    A new strain that degrades the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) was isolated from soil, which was exposed to factors related to the petrochemical industry. According to its physiological, biochemical, cultural, and morphological traits, together with the sequence of the 16S rRNA gene, the strain was identified as Raoultella planticola 33-4ch. The strain could consume 2,4,5-T as a sole source of carbon and energy. The amount of 2,4,5-T in the culture medium decreased by 51% after five days of incubation. Raoultella planticola 33-4ch consumes 2,4,5-T to produce 4-chlorophenoxyacetic, phenoxyacetic, and 3-methyl-2,6-dioxo-4-hexenoic acids.

  1. Experimental inoculation of wild turkeys (Meleagris gallopavo) with Mycobacterium bovis.

    Science.gov (United States)

    Clarke, K R; Fitzgerald, S D; Hattey, J A; Bolin, C A; Berry, D E; Church, S V; Reed, W M

    2006-03-01

    Although avian species are known to be susceptible to infection with Mycobacterium spp. organisms, much remains unknown about the susceptibility of birds to infection with M. bovis. The objective of this current study was to determine if wild turkeys (Meleagris gallopavo) can be infected with M. bovis when inoculated by the oral or intratracheal route. Six turkeys were orally inoculated and another six were inoculated via the trachea with a high dose of M. bovis, 1 x 10(5) CFU/ml. Six turkeys were sham-inoculated controls. Two turkeys from each treatment group were sacrificed on days 30, 60, and 90 postinoculation. There were no gross or microscopic lesions consistent with mycobacteriosis in the 23 inoculated turkeys over the 90-day duration of this study. Fecal cultures were also consistently negative for M. bovis when sampled before inoculation and on days 1, 30, and 60 postinoculation. Two intratracheally inoculated turkeys were positive for M. bovis in visceral tissues at 30 days postinoculation. However, this finding was only indicative of passive persistence of mycobacteria in the tissues and not of infection, as there were no attendant lesions or clinical compromise to support infection. Thus, it can be concluded that young wild turkeys are resistant to infection with M. bovis and, therefore, pose minimal threat as reservoir or spillover hosts for this organism.

  2. Mycorrhizal inoculation affects the phytochemical content in strawberry fruits

    Directory of Open Access Journals (Sweden)

    Ana Paula Cecatto

    2016-04-01

    Full Text Available The aim of this research was to evaluate the effect of the inoculation date of arbuscular mycorrhizal fungi on the fruit quality and the content of phytochemicals in a strawberry soilless growing system. The experiment was performed in Huelva (Spain and was conducted in a greenhouse on the La Rábida Campus of Huelva University under natural light and temperature from October 2013 to June 2014. Three short-day strawberry cultivars (‘Splendor’, ‘Sabrina’ and ‘Fortuna’ were grown in polyethylene bags filled with coconut fibres. Randomized block design, with 3 repetitions and factorial arrangement (3 cultivars x 3 treatments, was established. Each replicate consisted of one bag with 12 plants supporting structures at 40 cm height. The treatments were: T1 = mycorrhizal inoculation in the transplantation; T2 = mycorrhizal inoculation 30 days after transplantation (DAT; and T0 = control treatment, without inoculation. Arbuscular mycorrhizal fungi inoculation significantly affected the contents of anthocyanin and phenolics. When the inoculation is performed in the transplantation, the fruits showed a high content of anthocyanin and total phenolics. The mycorrhizal inoculation influences decreasing the acidity in fruit throughout the growing season and increase firmness only during the early stage of production.

  3. Inoculation message treatments for curbing noncommunicable disease development.

    Science.gov (United States)

    Mason, Alicia M; Miller, Claude H

    2013-07-01

    To study the effect of various types of inoculation message treatments on resistance to persuasive and potentially deceptive health- and nutrition-related (HNR) content claims of commercial food advertisers. A three-phase experiment was conducted among 145 students from a Midwestern U.S. university. Quantitative statistical analyses were used to interpret the results. RESULTS provide clear evidence that integrating regulatory focus/fit considerations enhances the treatment effectiveness of inoculation messages. Inoculation messages that employed a preventative, outcome focus with concrete language were most effective at countering HNR advertising claims. The findings indicate that inoculation fosters resistance equally across the most common types of commercially advertised HNR product claims (e.g., absolute, general, and structure/function claims). As the drive to refine the inoculation process model continues, further testing and application of this strategy in a public health context is needed to counter ongoing efforts by commercial food advertisers to avoid government regulations against deceptive practices such as dubious health/nutrition claims. This research advances inoculation theory by providing evidence that 1) good regulatory fit strengthens the effect of refutational preemption and 2) an inoculation approach is highly effective at fostering resistance to commercial advertisers' HNR content claims. This macro approach appears far superior to education or information-based promotional health campaigns targeted solely at specific populations demonstrating rising rates of noncommunicable disease.

  4. Efficacy of Sanitizer Treatments on Survival and Growth Parameters of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on Fresh-Cut Pieces of Cantaloupe during Storage.

    Science.gov (United States)

    Ukuku, Dike O; Huang, Lihan; Sommers, Christopher

    2015-07-01

    For health reasons, people are consuming fresh-cut fruits with or without minimal processing and, thereby, exposing themselves to the risk of foodborne illness if such fruits are contaminated with bacterial pathogens. This study investigated survival and growth parameters of Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and aerobic mesophilic bacteria transferred from cantaloupe rind surfaces to fresh-cut pieces during fresh-cut preparation. All human bacterial pathogens inoculated on cantaloupe rind surfaces averaged ∼4.8 log CFU/cm(2), and the populations transferred to fresh-cut pieces before washing treatments ranged from 3 to 3.5 log CFU/g for all pathogens. A nisin-based sanitizer developed in our laboratory and chlorinated water at 1,000 mg/liter were evaluated for effectiveness in minimizing transfer of bacterial populations from cantaloupe rind surface to fresh-cut pieces. Inoculated and uninoculated cantaloupes were washed for 5 min before fresh-cut preparation and storage of fresh-cut pieces at 5 and 10°C for 15 days and at 22°C for 24 h. In fresh-cut pieces from cantaloupe washed with chlorinated water, only Salmonella was found (0.9 log CFU/g), whereas E. coli O157:H7 and L. monocytogenes were positive only by enrichment. The nisin-based sanitizer prevented transfer of human bacteria from melon rind surfaces to fresh-cut pieces, and the populations in fresh-cut pieces were below detection even by enrichment. Storage temperature affected survival and the growth rate for each type of bacteria on fresh-cut cantaloupe. Specific growth rates of E. coli O157:H7, Salmonella, and L. monocytogenes in fresh-cut pieces were similar, whereas the aerobic mesophilic bacteria grew 60 to 80 % faster and had shorter lag phases.

  5. Listeria monocytogenes and the inflammasome: from cytosolic bacteriolysis to tumor immunotherapy

    Science.gov (United States)

    Theisen, Erin; Sauer, John-Demian

    2016-01-01

    Inflammasomes are cytosolic innate immune surveillance systems that recognize a variety of danger signals, including those from pathogens. Listeria monocytogenes is a Gram-positive intracellular bacterium evolved to live within the harsh environment of the host cytosol. Further, L. monocytogenes can activate a robust cell-mediated immune response that is being harnessed as an immunotherapeutic platform. Access to the cytosol is critical for both causing disease and for inducing a protective immune response, and it is hypothesized that the cytosolic innate immune system, including the inflammasome, is critical for both host protection and induction of long term immunity. L. monocytogenes can activate a variety of inflammasomes via its pore-forming toxin Listeriolysin-O, flagellin, or DNA released through bacteriolysis; however, inflammasome activation attenuates L. monocytogenes, and as such, L. monocytogenes has evolved a variety of ways to limit inflammasome activation. Surprisingly, inflammasome activation also impairs the host cell-mediated immune response. Thus understanding how L. monocytogenes activates or avoids detection by the inflammasome is critical to understand the pathogenesis of L. monocytogenes and improve the cell-mediated immune response generated to L. monocytogenes for more effective immunotherapies. PMID:27460808

  6. Stability of sublethal acid stress adaptaion and induced cross protection against lauric arginate in Listeria monocytogenes

    Science.gov (United States)

    The stability of acid stress adaptation in Listeria monocytogenes and its induced cross protection effect against GRAS (generally recognized as safe) antimicrobial compounds has never been investigated before. In the present study, the acid stress adaptation in L. monocytogenes was initially induced...

  7. Listeria monocytogenes DNA glycosylase AdiP affects flagellar motility, biofilm formation, virulence, and stress responses

    Science.gov (United States)

    The temperature-dependent alteration of flagellar motility gene expression is critical for the foodborne pathogen Listeria monocytogenes to respond to a changing environment. In this study, a genetic determinant, L. monocytogenes f2365_0220 (lmof2365_0220), encoding a putative protein that is struct...

  8. A dynamical systems approach to actin-based motility in Listeria monocytogenes

    Science.gov (United States)

    Hotton, S.

    2010-11-01

    A simple kinematic model for the trajectories of Listeria monocytogenes is generalized to a dynamical system rich enough to exhibit the resonant Hopf bifurcation structure of excitable media and simple enough to be studied geometrically. It is shown how L. monocytogenes trajectories and meandering spiral waves are organized by the same type of attracting set.

  9. Influence of temperature on acid-stress adaptation in Listeria monocytogenes

    Science.gov (United States)

    Several factors play critical roles in controlling the induction of acid-stress adaptation in L. monocytogenes. Our findings show that temperature plays a significant role in the induction of acid-stress adaptation in Listeria monocytogenes and two distinct patterns were observed: (I) Presence of su...

  10. Listeria monocytogenes detection and behaviour in food and in the environment.

    NARCIS (Netherlands)

    Beumer, R.R.

    1997-01-01

    In this thesis, Listeria monocytogenes, a bacterial pathogen was studied, with emphasis on the detection and behaviour in food and environment.Epidemics of foodborne listeriosis have raised concern about the incidence of L. monocytogenes in foods. In the past 10-15 years listeriosis has emerged as a

  11. Diversity assessment of Listeria monocytogenes biofilm formation: Impact of growth condition, serotype and strain origin

    NARCIS (Netherlands)

    Kadam, S.R.; Besten, den H.M.W.; Veen, van der S.; Zwietering, M.H.; Moezelaar, R.; Abee, T.

    2013-01-01

    The foodborne pathogen Listeria monocytogenes has the ability to produce biofilms in food-processing environments and then contaminate food products, which is a major concern for food safety. The biofilm forming behavior of 143 L. monocytogenes strains was determined in four different media that wer

  12. A novel suicide plasmid for efficient gene mutation in Listeria monocytogenes

    Science.gov (United States)

    Although several plasmids have been used in Listeria monocytogenes for generating mutants by allelic exchange, construction of L. monocytogenes mutants has been inefficient due to lack of effective selection markers for first and second recombination events. To address this problem, we have develope...

  13. Betaine and L-carnitine transport by Listeria monocytogenes Scott A in response to osmotic signals

    NARCIS (Netherlands)

    Verheul, Annette; Glaasker, Erwin; Poolman, Bert; Abee, Tjakko

    1997-01-01

    The naturally occurring compatible solutes betaine and L-carnitine allow the food-borne pathogen Listeria monocytogenes to adjust to environments of high osmotic strength. Previously, it was demonstrated that L. monocytogenes possesses an ATP-dependent L-carnitine transporter. The present study reve

  14. Isolation and characterization of an atypical Listeria monocytogenes associated with a canine urinary tract infection

    Science.gov (United States)

    Listeria monocytogenes, a well-described cause of encephalitis and abortion in ruminants and of food-borne illness in humans, is rarely associated with disease in companion animals. A case of urinary tract infection associated with an atypical, weakly hemolytic L. monocytogenes strain is described i...

  15. Performance of stress resistant variants of Listeria monocytogenes in mixed species biofilms with Lactobacillus plantarum

    NARCIS (Netherlands)

    Metselaar, K.I.; Saa Ibusquiza, P.; Ortiz Camargo, A.R.; Krieg, M.; Zwietering, M.H.; Besten, den H.M.W.; Abee, T.

    2015-01-01

    Population diversity and the ability to adapt to changing environments allow Listeria monocytogenes to grow and survive under a wide range of environmental conditions. In this study, we aimed to evaluate the performance of a set of acid resistant L. monocytogenes variants in mixed-species biofilms w

  16. Surface attachment of Listeria monocytogenes is induced by sublethal concentrations of alcohol at low temperatures.

    Science.gov (United States)

    Gravesen, Anne; Lekkas, Charidimos; Knøchel, Susanne

    2005-09-01

    Sublethal concentrations of ethanol or isopropanol increased attachment of Listeria monocytogenes at 10, 20, or 30 degrees C; no induction occurred at 37 degrees C. The alcohol induction phenotype was retained in sigB and cesRK mutants; however, the degree of induction was affected. These results suggest that alcohol may contribute to the persistence of L. monocytogenes.

  17. Physiology of Listeria monocytogenes in relation to food components and biopreservation.

    NARCIS (Netherlands)

    Verheul, A.

    1997-01-01

    Listeria monocytogenes is an important foodborne pathogen that has been responsible for severe infections in humans. The ubiquitous distribution of L. monocytogenes in the environment and its ability to grow at refrigeration temperature and at high osmolarity are of paramount importance for its haz

  18. A multiplex PCR for detection of Listeria monocytogenes and its lineages.

    Science.gov (United States)

    Rawool, Deepak B; Doijad, Swapnil P; Poharkar, Krupali V; Negi, Mamta; Kale, Satyajit B; Malik, S V S; Kurkure, Nitin V; Chakraborty, Trinad; Barbuddhe, Sukhadeo B

    2016-11-01

    A novel multiplex PCR assay was developed to identify genus Listeria, and discriminate Listeria monocytogenes and its major lineages (LI, LII, LIII). This assay is a rapid and inexpensive subtyping method for screening and characterization of L. monocytogenes. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Betaine and L-carnitine transport by Listeria monocytogenes Scott A in response to osmotic signals

    NARCIS (Netherlands)

    Verheul, Annette; Glaasker, Erwin; Poolman, Bert; Abee, Tjakko

    1997-01-01

    The naturally occurring compatible solutes betaine and L-carnitine allow the food-borne pathogen Listeria monocytogenes to adjust to environments of high osmotic strength. Previously, it was demonstrated that L. monocytogenes possesses an ATP-dependent L-carnitine transporter. The present study

  20. The fate of Listeria monocytogenes in brine and on Gouda cheese following artificial contamination during brining

    NARCIS (Netherlands)

    Wemmenhove, E.; Beumer, R.R.; Hooijdonk, van A.C.M.; Zwietering, M.H.; Wells-Bennik, M.H.J.

    2014-01-01

    The fate of 3 different Listeria monocytogenes strains (Scott A, 2F and 6E) was studied independently in brine and on factory-scale Gouda cheeses that had been submerged in brine that was artificially contaminated with these individual strains. Viable numbers of L. monocytogenes in the brine

  1. Diversity assessment of Listeria monocytogenes biofilm formation: Impact of growth condition, serotype and strain origin

    NARCIS (Netherlands)

    Kadam, S.R.; Besten, den H.M.W.; Veen, van der S.; Zwietering, M.H.; Moezelaar, R.; Abee, T.

    2013-01-01

    The foodborne pathogen Listeria monocytogenes has the ability to produce biofilms in food-processing environments and then contaminate food products, which is a major concern for food safety. The biofilm forming behavior of 143 L. monocytogenes strains was determined in four different media that

  2. Microbiological criteria for Listeria monocytogenes in foods under special consideration of risk assessment approaches

    DEFF Research Database (Denmark)

    Nørrung, Birgit

    2000-01-01

    This paper shortly summarizes data related to risk assessment of Listeria monocytogenes. From available data on risk assessment, it is concluded that the levels of L. monocytogenes consumed is an important factor affecting the incidence of listeriosis. Foods that do not support the growth of L. m...

  3. CRAC channel is inhibited by neomycin in a Ptdlns(4,5)P2-independent manner.

    Science.gov (United States)

    Huang, Kun; Wang, Xuemei; Liu, Yanjun; Zhao, Yi

    2015-03-01

    Depletion of intracellular Ca(2+) stores evokes store-operated Ca(2+) entry through the Ca(2+) release-activated Ca(2+) (CRAC) channels. In this study, we found that the store-operated Ca(2+) entry was inhibited by neomycin, an aminoglycoside that strongly binds phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2). Patch clamp recordings revealed that neomycin blocked the CRAC currents reconstituted by co-expression of Orai1 and Stim1 in HEK293 cells. Using a rapamycin-inducible PtdIns(4,5)P2-specific phosphatase (Inp54p) system to manipulate the PtdIns(4,5)P2 in the plasma membrane, we found that the CRAC current was not altered by PtdIns(4,5)P2 depletion. This result suggests that PtdIns(4,5)P2 is not required for CRAC channel activity, and thereby, neomycin inhibits CRAC channels in a manner that is independent of neomycin-PtdIns(4,5)P2 binding.

  4. Emerging roles of PtdIns(4,5)P2--beyond the plasma membrane.

    Science.gov (United States)

    Tan, Xiaojun; Thapa, Narendra; Choi, Suyong; Anderson, Richard A

    2015-11-15

    Phosphoinositides are a collection of lipid messengers that regulate most subcellular processes. Amongst the seven phosphoinositide species, the roles for phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] at the plasma membrane, such as in endocytosis, exocytosis, actin polymerization and focal adhesion assembly, have been extensively studied. Recent studies have argued for the existence of PtdIns(4,5)P2 at multiple intracellular compartments, including the nucleus, endosomes, lysosomes, autolysosomes, autophagic precursor membranes, ER, mitochondria and the Golgi complex. Although the generation, regulation and functions of PtdIns(4,5)P2 are less well-defined in most other intracellular compartments, accumulating evidence demonstrates crucial roles for PtdIns(4,5)P2 in endolysosomal trafficking, endosomal recycling, as well as autophagosomal pathways, which are the focus of this Commentary. We summarize and discuss how phosphatidylinositol phosphate kinases, PtdIns(4,5)P2 and PtdIns(4,5)P2-effectors regulate these intracellular protein and membrane trafficking events.

  5. Smooth muscle length-dependent PI(4,5)P2 synthesis and paxillin tyrosine phosphorylation.

    Science.gov (United States)

    Sul, D; Baron, C B; Broome, R; Coburn, R F

    2001-07-01

    We studied effects of increasing the length of porcine trachealis muscle on 5.5 microM carbachol (CCh)-evoked phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] synthesis and other parameters of phosphatidylinositol (PI) turnover. PI(4,5)P2 resynthesis rates in muscle held at 1.0 optimal length (L(o)), measured over the first 6 min of CCh stimulation, were 140 +/- 12 and 227 +/- 14% of values found in muscle held at 0.5 L(o) and in free-floating muscle, respectively. Time-dependent changes in cellular masses of PI(4,5)P2, PI, and phosphatidic acid, and PI resynthesis rates, were also altered by the muscle length at which contraction occurred. In free-floating muscle, CCh did not evoke increases in tyrosine-phosphorylated paxillin (PTyr-paxillin), an index of beta1-integrin signaling; however, there were progressive increases in PTyr-paxillin in muscle held at 0.5 and 1.0 L(o) during contraction, which correlated with increases in PI(4,5)P2 synthesis rates. These data indicate that PI(4,5)P2 synthesis rates and other parameters of CCh-stimulated inositol phospholipid turnover are muscle length-dependent and provide evidence that supports the hypothesis that length-dependent beta1-integrin signals may exert control on CCh-activated PI(4,5)P2 synthesis.

  6. Time of action of 4.5 S RNA in Escherichia coli translation

    DEFF Research Database (Denmark)

    Brown, S

    1989-01-01

    translocated but not yet released the uncharged tRNA, indicating that this is the point at which 4.5 S RNA enters translation. The release of 4.5 S RNA from polysomes is affected by antibiotics that inhibit protein synthesis. The antibiotic-sensitivity of this release indicates that 4.5 S RNA exits......A new class of suppressor mutants helps to define the role of 4.5 S RNA in translation. The suppressors reduce the requirement for 4.5 S RNA by increasing the intracellular concentration of uncharged tRNA. Suppression probably occurs by prolonging the period in which translating ribosomes have...... the ribosome following translocation and prior to release of protein synthesis elongation factor G. These results indicate that 4.5 S RNA acts immediately after ribosomal translocation. A model is proposed in which 4.5 S RNA stabilizes the post-translocation state by replacing 23 S ribosomal RNA as a binding...

  7. LPS-induced clustering of CD14 triggers generation of PI(4,5)P2.

    Science.gov (United States)

    Płóciennikowska, Agnieszka; Zdioruk, Mykola I; Traczyk, Gabriela; Świątkowska, Anna; Kwiatkowska, Katarzyna

    2015-11-15

    Bacterial lipopolysaccharide (LPS) induces strong pro-inflammatory reactions after sequential binding to CD14 protein and TLR4 receptor. Here, we show that CD14 controls generation of phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] in response to LPS binding. In J774 cells and HEK293 cells expressing CD14 exposed to 10-100 ng/ml LPS, the level of PI(4,5)P2 rose in a biphasic manner with peaks at 5-10 min and 60 min. After 5-10 min of LPS stimulation, CD14 underwent prominent clustering in the plasma membrane, accompanied by accumulation of PI(4,5)P2 and type-I phosphatidylinositol 4-phosphate 5-kinase (PIP5K) isoforms Iα and Iγ (encoded by Pip5k1a and Pip5k1c, respectively) in the CD14 region. Clustering of CD14 with antibodies, without LPS and TLR4 participation, was sufficient to trigger PI(4,5)P2 elevation. The newly generated PI(4,5)P2 accumulated in rafts, which also accommodated CD14 and a large portion of PIP5K Iα and PIP5K Iγ. Silencing of PIP5K Iα and PIP5K Iγ, or application of drugs interfering with PI(4,5)P2 synthesis and availability, abolished the LPS-induced PI(4,5)P2 elevation and inhibited downstream pro-inflammatory reactions. Taken together, these data indicate that LPS induces clustering of CD14, which triggers PI(4,5)P2 generation in rafts that is required for maximal pro-inflammatory signaling of TLR4.

  8. Property study of poly nitro compounds of cis-syn-cis-2, 6-dioxodecahydro-lH, 5H-diimidazo [4, 5-b: 4', 5'-e] pyrazine

    Science.gov (United States)

    Liu, Yang; Xu, Zhibin; Xu, Yudong; Xu, Liang; Meng, Zihui

    2017-03-01

    Poly nitro group substituted cis-syn-cis-2, 6-dioxodecahydro-lH, 5H-diimidazo [4, 5-b: 4', 5'-e] pyrazine derivatives are synthesized by modified method and adequately characterized. All compounds have good performance both in density (ρ> 1.85 g/cm3) and high detonation velocity (vD > 8800 m/s, calculated). Some representative compounds, for example, 4 (vD: 9405 ms-1; P: 41.6 GPa) and 5 (vD:9781 ms-1; P: 45.6 GPa) exhibit excellent detonation performances, which are comparable with current energetic compounds such as RDX (vD: 8724 ms-1; P: 35.2 GPa) and HMX (vD:9059 ms-1; P: 39.2 GPa). Considering the sensitivity increasing with the number of nitro group, two componds with tetranitro groups (2 and 3) are worthy of deep research.

  9. Syntheses and crystal structures of two ionic liquids with halogen-bonding groups: 4,5-dibromo- and 4,5-diiodo-1-butyl-3-methylimidazolium trifluoromethanesulfonates

    Science.gov (United States)

    Mukai, Tomohiro; Nishikawa, Keiko

    2010-05-01

    We have prepared and characterized two novel Lewis acidic ionic liquids, 4,5-dibromo- and 4,5-diiodo-1-butyl-3-methylimidazolium trifluoromethanesulfonates, using differential scanning calorimetry and single-crystal X-ray analysis. The effect of the halogen species on the phase transition behaviour and the cation-anion interacting geometry was investigated. The minor difference in chemical structure strongly affects the melting point, glass transition temperature and crystal structure because of the different halogen-bonding strength and linearity between C-Br⋯O and C-I⋯O. Both the salts melt above room temperature, but the fused salts show glass-forming property and poor crystallizability.

  10. Comparative experimental infection of Listeria monocytogenes and Listeria ivanovii in bovine trophoblasts.

    Science.gov (United States)

    Rocha, Cláudia E; Mol, Juliana P S; Garcia, Luize N N; Costa, Luciana F; Santos, Renato L; Paixão, Tatiane A

    2017-01-01

    Listeria monocytogenes is a Gram-positive, facultative intracellular and invasive bacterium that has tropism to the placenta, and causes fetal morbidity and mortality in several mammalian species. While infection with L. monocytogenes and L. ivanovii are known as important causes of abortion and reproductive failure in cattle, the pathogenesis of maternal-fetal listeriosis in this species is poorly known. This study used the bovine chorioallantoic membrane explant model to investigate the kinetics of L. monocytogenes, L. ivanovii, and L. innocua infections in bovine trophoblastic cells for up to 8 h post infection. L. monocytogenes and L. ivanovii were able to invade and multiply in trophoblastic cells without causing cell death or inducing expression of pro-inflammatory genes. Although L. innocua was unable to multiply in bovine trophoblastic cells, it induced transcription of the pro-inflammatory mediator CXCL6. This study demonstrated for the first time the susceptibility of bovine trophoblastic cells to L. monocytogenes and L. ivanovii infection.

  11. Synthesis of [4,5-[sup 3]H-Leu[sup 4

    Energy Technology Data Exchange (ETDEWEB)

    Birtle, T.; White, A.J.; Woodhouse, D.P. (Cambridge Research Biochemicals, Billingham (United Kingdom))

    1994-04-01

    The synthesis of salmon calcitonin, a C-terminal amide dotriacontapeptide, labelled with tritium in the leucine residue at position 4 to a specific activity of 100Ci mmole[sup -1] is described. The peptide was assembled using the Fmoc-Polyamide solid-phase synthesis strategy incorporating tritium labelled leucine, in the form of Fmoc-4,5-[sup 3]H-leucine-pentafluorophenylester, at the appropriate stage. The Fmoc-4,5-[sup 3]H-leucine-pentafluorophenylester was prepared via a multistage synthesis from 4,5-dehydroleucine. (Author).

  12. Density functional study on ionic liquid of 1-propyl-4,5-dibromo-3-methylimidazolium bromide

    Science.gov (United States)

    Lü, Renqing; Wang, Shutao; Lu, Yukun

    2011-03-01

    The density functional method and DNP basis set were employed to study 1-pair, 2-pair, and 3-pair of cation-anion interactions of 1-propyl-4,5-dibromo-3-methylimidazolium bromides. The calculated results reveal that H 2 atoms of 1-propyl-4,5-dibromo-3-methylimidazolium form hydrogen bondings with Br -. The natural bond orbital (NBO) and atoms in molecules (AIM) analyzes show that halogen bondings between Br - anion and imidazolium ring substituted bromine atoms were formed in the gas phase, in agreement with the crystal phase of 1-propyl-4,5-dibromo-3-methylimidazolium bromide which is governed by both hydrogen bondings and halogen bondings.

  13. Changes in Aerobic Plate and Escherichia coli-Coliform Counts and in Populations of Inoculated Foodborne Pathogens on Inshell Walnuts during Storage.

    Science.gov (United States)

    Frelka, John C; Davidson, Gordon R; Harris, Linda J

    2016-07-01

    After harvest, inshell walnuts are dried using low-temperature forced air and are then stored in bins or silos for up to 1 year. To better understand the survival of bacteria on inshell walnuts, aerobic plate counts (APCs) and Escherichia coli?coliform counts (ECCs) were evaluated during commercial storage (10 to 12°C and 63 to 65% relative humidity) over 9 months. APCs decreased by 1.4 to 2.0 log CFU per nut during the first 5 months of storage, and ECCs decreased by 1.3 to 2.2 log CFU per nut in the first month of storage. Through the remaining 4 to 8 months of storage, APCs and ECCs remained unchanged (P > 0.05) or decreased by CFU per nut per month. Similar trends were observed on kernels extracted from the inshell walnuts. APCs and ECCs were consistently and often significantly higher on kernels extracted from visibly broken inshell walnuts than on kernels extracted from visibly intact inshell walnuts. Parameters measured in this study were used to determine the survival of five-strain cocktails of E. coli O157:H7, Listeria monocytogenes, and Salmonella inoculated onto freshly hulled inshell walnuts (∼8 log CFU/g) after simulated commercial drying (10 to 12 h; 40°C) and simulated commercial storage (12 months at 10°C and 65% relative humidity). Populations declined by 2.86, 5.01, and 4.40 log CFU per nut for E. coli O157:H7, L. monocytogenes, and Salmonella, respectively, after drying and during the first 8 days of storage. Salmonella populations changed at a rate of -0.33 log CFU per nut per month between days 8 and 360, to final levels of 2.83 ± 0.79 log CFU per nut. E. coli and L. monocytogenes populations changed by -0.17 log CFU per nut per month and -0.26 log CFU per nut per month between days 8 and 360, respectively. For some samples, E. coli or L. monocytogenes populations were below the limit of detection by plating (0.60 log CFU per nut) by day 183 or 148, respectively; at least one of the six samples was positive at each subsequent sampling

  14. Evaluation of lactic acid bacterium fermentation products and food-grade chemicals to control Listeria monocytogenes in blue crab (Callinectes sapidus) meat.

    Science.gov (United States)

    Degnan, A J; Kaspar, C W; Otwell, W S; Tamplin, M L; Luchansky, J B

    1994-01-01

    Fresh blue crab (Callinectes sapidus) meat was obtained from retail markets in Florida and sampled for viable Listeria monocytogenes. The pathogen was found in crabmeat in three of four different lots tested by enrichment and at levels of 75 CFU/g in one of the same four lots by direct plating. Next, crabmeat was steam sterilized, inoculated with a three-strain mixture of L. monocytogenes (ca. 5.5 log10 CFU/g), washed with various lactic acid bacterium fermentation products (2,000 to 20,000 arbitrary units [AU]/ml of wash) or food-grade chemicals (0.25 to 4 M), and stored at 4 degrees C. Counts of the pathogen remained relatively constant in control samples during storage for 6 days, whereas in crabmeat washed with Perlac 1911 or MicroGard (10,000 to 20,000 AU), numbers initially decreased (0.5 to 1.0 log10 unit/g) but recovered to original levels within 6 days. Numbers of L. monocytogenes cells decreased 1.5 to 2.7 log10 units/g of crabmeat within 0.04 day when washed with 10,000 to 20,000 AU of Alta 2341, enterocin 1083, or Nisin per ml. Thereafter, counts increased 0.5 to 1.6 log10 units within 6 days. After washing with food-grade chemicals, modest reductions (0.4 to 0.8 log10 unit/g) were observed with sodium acetate (4 M), sodium diacetate (0.5 or 1 M), sodium lactate (1 M), or sodium nitrite (1.5 M). However, Listeria counts in crabmeat washed with 2 M sodium diacetate decreased 2.6 log10 units/g within 6 days. In addition, trisodium phosphate reduced L. monocytogenes counts from 1.7 (0.25 M) to > 4.6 (1 M) log10 units/g within 6 days.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7944362

  15. Phage display-derived binders able to distinguish Listeria monocytogenes from other Listeria species.

    Directory of Open Access Journals (Sweden)

    Josephine Morton

    Full Text Available The objective of this study was to produce phage display-derived binders with the ability to distinguish Listeria monocytogenes from other Listeria spp., which may have potential utility to enhance detection of Listeria monocytogenes. To obtain binders with the desired binding specificity a series of surface and solution phage-display biopannings were performed. Initially, three rounds of surface biopanning against gamma-irradiated L. monocytogenes serovar 4b cells were performed followed by an additional surface biopanning round against L. monocytogenes 4b which included prior subtraction biopanning against gamma-irradiated L. innocua cells. In an attempt to further enhance binder specificity for L. monocytogenes 4b two rounds of solution biopanning were performed, both rounds included initial subtraction solution biopanning against L. innocua. Subsequent evaluations were performed on the phage clones by phage binding ELISA. All phage clones tested from the second round of solution biopanning had higher specificity for L. monocytogenes 4b than for L. innocua and three other foodborne pathogens (Salmonella spp., Escherichia coli and Campylobacter jejuni. Further evaluation with five other Listeria spp. revealed that one phage clone in particular, expressing peptide GRIADLPPLKPN, was highly specific for L. monocytogenes with at least 43-fold more binding capability to L. monocytogenes 4b than to any other Listeria sp. This proof-of-principle study demonstrates how a combination of surface, solution and subtractive biopanning was used to maximise binder specificity. L. monocytogenes-specific binders were obtained which could have potential application in novel detection tests for L. monocytogenes, benefiting both the food and medical industries.

  16. Phage display-derived binders able to distinguish Listeria monocytogenes from other Listeria species.

    Science.gov (United States)

    Morton, Josephine; Karoonuthaisiri, Nitsara; Charlermroj, Ratthaphol; Stewart, Linda D; Elliott, Christopher T; Grant, Irene R

    2013-01-01

    The objective of this study was to produce phage display-derived binders with the ability to distinguish Listeria monocytogenes from other Listeria spp., which may have potential utility to enhance detection of Listeria monocytogenes. To obtain binders with the desired binding specificity a series of surface and solution phage-display biopannings were performed. Initially, three rounds of surface biopanning against gamma-irradiated L. monocytogenes serovar 4b cells were performed followed by an additional surface biopanning round against L. monocytogenes 4b which included prior subtraction biopanning against gamma-irradiated L. innocua cells. In an attempt to further enhance binder specificity for L. monocytogenes 4b two rounds of solution biopanning were performed, both rounds included initial subtraction solution biopanning against L. innocua. Subsequent evaluations were performed on the phage clones by phage binding ELISA. All phage clones tested from the second round of solution biopanning had higher specificity for L. monocytogenes 4b than for L. innocua and three other foodborne pathogens (Salmonella spp., Escherichia coli and Campylobacter jejuni). Further evaluation with five other Listeria spp. revealed that one phage clone in particular, expressing peptide GRIADLPPLKPN, was highly specific for L. monocytogenes with at least 43-fold more binding capability to L. monocytogenes 4b than to any other Listeria sp. This proof-of-principle study demonstrates how a combination of surface, solution and subtractive biopanning was used to maximise binder specificity. L. monocytogenes-specific binders were obtained which could have potential application in novel detection tests for L. monocytogenes, benefiting both the food and medical industries.

  17. Inoculation of maize with Azospirillum brasilense in the seed furrow

    OpenAIRE

    Tâmara Prado de Morais; Césio Humberto de Brito; Afonso Maria Brandão; Wender Santos Rezende

    2016-01-01

    ABSTRACT Several studies addressing the inoculation of cereals with diazotrophic microorganisms can be found in the literature. However, in many experiments, investigators have overlooked the feasibility of applying these microorganisms to the furrow together with the seed, and the effect of bacterial concentration on phytostimulation. The aim of this work was to evaluate the effect of doses of an inoculant based on Azospirillum brasilense, applied to the seed furrow when planting maize, comb...

  18. Albendazole inhibits Pneumocystis carinii proliferation in inoculated immunosuppressed mice.

    OpenAIRE

    Bartlett, M S; Edlind, T D; Lee, C. H.; Dean, R; Queener, S F; Shaw, M M; Smith, J W.

    1994-01-01

    Albendazole, a benzimidazole derivative widely used for treating helminth infections, was successfully used to treat and prevent development of Pneumocystis carinii pneumonia in transtracheally inoculated immunosuppressed mice. For treatment, 3 weeks postinoculation, albendazole at 300 and 600 mg/kg of body weight per day was administered in food for 3 weeks. For prophylaxis, albendazole was begun on the same day as inoculation at 300 mg/kg/day for 7 days, and then the dose was reduced to 150...

  19. The 4.5 S RNA gene of Escherichia coli is essential for cell growth

    DEFF Research Database (Denmark)

    Brown, S; Fournier, M J

    1984-01-01

    The Escherichia coli gene coding for the metabolically stable 4.5 S RNA (ffs) has been shown to be required for cell viability. Essentiality was demonstrated by examining the recombination behavior of substitution mutations of ffs generated in vitro. Substitution mutants of ffs are able to replace...... the chromosomal allele only in the presence of a second, intact copy of ffs. Independent evidence of essentiality and the finding that 4.5 S RNA is important for protein synthetic activity came from characterization of cells dependent on the lac operon inducer isopropyl-beta-D-thiogalactoside for ffs gene...... expression. Here, a strain dependent on isopropyl-beta-D-thiogalactoside for 4.5 S RNA synthesis was developed by inactivation of the chromosomal ffs allele and lysogenization by a lambda phage containing 4.5 S DNA fused to a hybrid trp-lac promoter. Withdrawal of the thiogalactoside leads to a deficiency...

  20. Quantitative uranium speciation with U M{sub 4,5}-edge HERFD absorption spectra

    Energy Technology Data Exchange (ETDEWEB)

    Kvashnina, Kristina O.; Rossberg, Andre [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Molecular Structures

    2017-06-01

    This report gives a brief description of the quantitative uranium speciation performed by iterative transformation factor analysis (ITFA) of High Energy Resolution X-ray Fluorescence Detection (HERFD) data collected at the M{sub 4,5} edge.

  1. Antibacterial activity of synthesized 2,4,5-trisubstituted imidazole derivatives

    Digital Repository Service at National Institute of Oceanography (India)

    Khan, M.S.; Siddiqui, S.A.; Siddiqui, M.S.R.A.; Goswami, U.; Srinivasan, K.V.; Khan, M.I.

    Some novel chemically synthesized 2,4,5-trisubstituted imidazoles from aryl aldehydes and 1,2-diketones or a-hydroxyketone were screened against eight different human pathogenic bacteria and fungi. Seven compounds were found to be active against...

  2. Calcium Directly Regulates Phosphatidylinositol 4,5-Bisphosphate Headgroup Conformation and Recognition

    DEFF Research Database (Denmark)

    Bilkova, Eva; Pleskot, Roman; Rissanen, Sami

    2017-01-01

    The orchestrated recognition of phosphoinositides and concomitant intracellular release of Ca2+ is pivotal to almost every aspect of cellular processes, including membrane homeostasis, cell division and growth, vesicle trafficking, as well as secretion. Although Ca2+ is known to directly impact...... phosphoinositide clustering, little is known about the molecular basis for this or its significance in cellular signaling. Here, we study the direct interaction of Ca2+ with phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), the main lipid marker of the plasma membrane. Electrokinetic potential measurements of PI......(4,5)P2 containing liposomes reveal that Ca2+ as well as Mg2+ reduce the zeta potential of liposomes to nearly background levels of pure phosphatidylcholine membranes. Strikingly, lipid recognition by the default PI(4,5)P2 lipid sensor, phospholipase C delta 1 pleckstrin homology domain (PLC δ1-PH...

  3. Investigation of the properties of 4,5-dialkylated N-heterocyclic carbenes

    DEFF Research Database (Denmark)

    Urban, S.; Tursky, Matyas; Frohlich, R.

    2009-01-01

    The investigation of the electronic and steric properties of 4,5-disubstituted imidazolylidenes is reported, as well as their successful application as organocatalysts in the formation of gamma-butyrolactones by conjugate Umpolung....

  4. SHG Materials Based on the AlPO4-5 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Large AlPO4-5 molecular sieve single crystals with high optical quality were synthesized hydrothermally by using TPA as template. As-synthesized crystals were calcined under O2 atmosphere to remove the organic templates in the channels. Disperse-Red-1 (DR1) and p-nitroaniline (pNA) molecules have been successfully incorporated into the one-dimensional channels of AlPO4-5 single crystals respectively by means of vapor phase diffusion. XRD patterns reveal that the loading of organic molecules has not destroyed the structures of AlPO4-5 crystals. Polarizing microscope and SHG results indicate that the DR1 and pNA molecules are well aligned in a preferred direction along the crystal channels. The different polarization-dependence SH intensity shows that different SHG processes occur in the DR1- and pNA-loaded AlPO4-5 crystals.

  5. Facile construction of substituted pyrimido[4,5-d]pyrimidones by transformation of enaminouracil

    Directory of Open Access Journals (Sweden)

    Wafaa S. Hamama

    2013-03-01

    Full Text Available The reaction of 6-amino-1,3-dimethylpyrimidine-2,4(1H,3H-dione (1 as a binucleophile with primary aromatic or heterocyclic amines and formaldehyde or aromatic (heterocyclic aldehydes in a molar ratio (1:1:2 gave the pyrimido[4,5-d]pyrimidin-2,4-dione ring systems 2–5. Treatment of 1 with diamines and formalin in molar ratio (2:1:4 gave the bis-pyrimido[4,5-d]pyrimidin-2,4-diones 6–8. Furthermore, substituted pyrimido[4,5-d]pyrimidin-2,4-diones with uracil derivative 11 or spiro indole 16 were synthesized. Synthesis of pyrimido[4,5-d]pyrimidin-2,4-diones with different substitution at C-5 and C-7 was achieved to give 13 and 18, respectively.

  6. Phosphatidylinositol 4,5-bisphosphate-dependent regulation of the output in lobster olfactory receptor neurons.

    Science.gov (United States)

    Bobkov, Yuriy V; Pezier, Adeline; Corey, Elizabeth A; Ache, Barry W

    2010-05-01

    Transient receptor potential (TRP) channels often play a role in sensory transduction, including chemosensory transduction. TRP channels, a common downstream target of phosphoinositide (PI) signaling, can be modulated by exogenous phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2], phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] and/or diacylglycerol (DAG). Lobster olfactory receptor neurons (ORNs) express a TRP-related, non-selective, calcium/magnesium-permeable, sodium/calcium-gated cation (SGC) channel. Here we report that PIs regulate the function of the calcium-activated form of the lobster channel. Sequestering of endogenous PI(4,5)P2, either with an anti-PI(4,5)P2 antibody or by electrostatic screening with polyvalent cations, blocks the channel. Exogenous PI(3,4,5)P3 activates the channel independently of intracellular sodium and/or calcium. Exogenous non-hydrolysable DAG analogs fail to change the gating parameters of the channel, suggesting the channel is insensitive to DAG. Electrophysiological recording from lobster ORNs in situ using a panel of pharmacological tools targeting the key components of both PI and DAG metabolism (phospholipase C, phosphoinositide 4-kinase and DAG kinase) extend these findings to the intact ORN. PI(4,5)P2 depletion suppresses both the odorant-evoked discharge and whole-cell current of the cells, and does so possibly independently of DAG production. Collectively, our results argue that PIs can regulate output in lobster ORNs, at least in part through their action on the lobster SGC channel.

  7. Map Reduce for DC4.5 and Ensemble Learning In Distributed Data Mining

    Directory of Open Access Journals (Sweden)

    E. Chandra

    2011-01-01

    Full Text Available MapReduce one of the distributed computing techniques is integrated with decision tree classifier C4.5 in the distributed environment and ensemble learning with its classifier. This paper proposes an algorithm to classify, predict data using MapReduce for DC4.5 with ensemble learning. Proposed algorithm increases the accuracy and scalability of the data. Noise handling in the decision trees with respect to the distributed data is also handled here.

  8. Synthesis and evaluation of antitumor activity ofsome thiazolo[4,5-b]pyridines

    Directory of Open Access Journals (Sweden)

    Ogurtsov V. V.

    2012-09-01

    Full Text Available Aim. To synthesize a series of novel 3H-thiazolo[4,5-b]pyridine-2-ones by structural modification of the core heterocycle in its N3- and N6-positions and to evaluate their anticancer activity in vitro on several tumor cell lines. Methods. Organic synthesis, 1H-NMR spectroscopy, trypan blue cell viability assay. Results. A new convenient synthetic approach was developed and optimized conditions were studied for the reaction of preparation of 3H- thiazolo[4,5-b]pyridin-2-one derivatives. 5,7-Dimethyl-3H-thiazolo[4,5-b]pyridin-2-one and 6-phenylazo-5,7- dimethyl-3H-thiazolo[4,5-b]pyridin-2-one were obtained by [3 + 3]cyclocondensation of 4-iminothiazolidone- 2 with acetylacetone and phenylazoacetylacetone in methanol medium in the presence of sodium methylate. They were used as starting compounds for further structural modification of the core thiazolo[4,5-b]pyridine heterocycle in its 3- and 6-positions. On the basis of in vitro cytotoxicity studies of synthesized compounds several structure-functional relationships underlying anticancer potential of 5,7-dimethyl-3H-thiazolo[4,5-b]pyridin- 2-one derivatives were identified. Conclusions. 3H-thiazolo[4,5-b]pyridin-2-one can be considered as a promising molecular scaffold for rational design of potential anticancer drug candidates. Introduction of phenylazo substitute at C6-position of 3H-thiazolo[4,5-b]pyridin-2-one proved to be the most efficient, as it led to 3-fold increase of its anticancer potential.

  9. Interactions between Rab and Arf GTPases regulate endosomal phosphatidylinositol-4,5-bisphosphate during endocytic recycling.

    Science.gov (United States)

    Shi, Anbing; Grant, Barth D

    2013-01-01

    After endocytosis, a selective endocytic recycling process returns many endocytosed molecules back to the plasma membrane. The RAB-10/Rab10 GTPase is known to be a key recycling regulator for specific cargo molecules. New evidence, focused on C. elegans RAB-10 in polarized epithelia, points to a key role of RAB-10 in the regulation of endosomal phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) levels. In turn, PI(4,5)P2 levels strongly influence the recruitment of many peripheral membrane proteins, including those important for vesicle budding through their membrane bending activities. Part of the effect of RAB-10 on endosomal PI(4,5)P2 is through its newly identified effector CNT-1, a predicted GTPase activating protein (GAP) of the small GTPase ARF-6/Arf6. In mammals PI(4,5)P2 generating enzymes are known Arf6 effectors. In C. elegans we found that RAB-10, CNT-1 and ARF-6 are present on the same endosomes, that RAB-10 recruits CNT-1 to endosomes, and that loss of CNT-1 or RAB-10 leads to overaccumulation of endosomal PI(4,5)P2, presumably via hyperactivation of endosomal ARF-6. In turn this leads to over-recruitment of PI(4,5)P2-dependent membrane-bending proteins RME-1/Ehd and SDPN-1/Syndapin/PACSIN. Conversely, in arf-6 mutants, endosomal PI(4,5)P2 levels were reduced and endosomal recruitment of RME-1 and SDPN-1 failed. This work makes an unexpected link between distinct classes of small GTPases that control endocytic recycling, and provides insight into how this interaction affects endosome function at the level of lipid phosphorylation.

  10. Effect of inoculating addition on machinability of gray cast iron

    Institute of Scientific and Technical Information of China (English)

    REN Fengzhang; LI Fengjun; LIU Weiming; MA Zhanhong; TIAN Baohong

    2009-01-01

    Gray cast irons were inoculated with FeSi75+RE and FeSi75+Sr inoculants. The changes of apex angle of the drills before and af-ter being used were used to evaluate machinability of gray cast irons. Effect of FeSi75+RE and FeSi75+Sr inoculants on mechanical proper-ties, machinability and sensibility of gray cast iron used in cylinder block were investigated. Experimental results showed that gray cast iron treated with 60%FeSi75+40% RE inoculants exhibited tensile strength consistently at about 295 MPa along with good hardness and im-proved metallurgical quality. While gray cast iron inoculated with 20%FeSi75+80% Sr inoculants exhibited the best machinability, the low-est cross-section sensibility and the least microhardness difference. The tool flank wear of the drill increased correspondingly with the in-crease of the microhardness difference of the matrix, indicating the great effect of homogeneity of the matrix on the machinability of gray cast iron.

  11. Conditions Affecting Shelf-Life of Inoculated Legume Seed

    Directory of Open Access Journals (Sweden)

    Greg Gemell

    2012-02-01

    Full Text Available Microbial inoculants are becoming more available as sustainable alternatives to fertilizers and other agrichemicals in broad-acre cropping. However, with the exception of legume inoculants little is understood about effective delivery and survival of the inoculum. Legume inoculants are applied to both seed and soil but seed inoculation is the most economical technique. Large quantities of pasture seed in Australia are inoculated by commercial seed coating companies, but the long-term survival of seed-applied inoculum is variable and monitoring of viability requires specialist microbiology skills and facilities. The aim of our research was to define optimum storage conditions for survival of rhizobia on legume seed and evaluate water activity as a means of monitoring shelf-life. The relationship between survival and water activity varied according to seed species, inoculum preparation, coating ingredients, initial water activity and time suggesting that storage conditions would need to be defined for each different combination. Although drying seeds after coating significantly reduced viable numbers of rhizobia, survival of rhizobia on dried commercially coated lucerne seed after 11 weeks was less variable than seeds that had not been dried. The highest numbers were maintained when seeds remained dry with water activities of between 0.47 and 0.38. The quality of inoculated seed could be improved by reducing the death rate of inoculum during preparation and providing optimum storage conditions for long-term survival.

  12. Inactivation of Listeria monocytogenes, Salmonella spp. and Escherichia coli O157:H7 on cantaloupes by octenidine dihydrochloride.

    Science.gov (United States)

    Upadhyay, Abhinav; Chen, Chi-Hung; Yin, Hsinbai; Upadhyaya, Indu; Fancher, Samantha; Liu, Yanyan; Nair, Meera Surendran; Jankelunas, Leanne; Patel, Jitendra R; Venkitanarayanan, Kumar

    2016-09-01

    The efficacy of a new generation disinfectant, octenidine dihydrochloride (OH), as wash and coating treatments for reducing Listeria monocytogenes (LM), Salmonella spp. (SAL), and Escherichia coli O157:H7 (EC) on cantaloupe was investigated. Cantaloupe rind plugs inoculated separately with the three bacterial species (∼8 log CFU/cm(2)) were washed for 1, 3, 5 min at 25 °C in water, or chlorine (200 ppm), ethanol (1%), OH (0.01, 0.05, 0.1%) and surviving populations were measured after treatment. Additionally, inoculated cantaloupe rind plugs were coated with 2% chitosan or chitosan containing OH (0.01, 0.05, 0.1%) and sampled for surviving pathogens. Subsequently, the antimicrobial efficacy of OH wash and coating (0.1, 0.2%) on whole cantaloupes was determined. All OH wash reduced LM, SAL, and EC on cantaloupe rinds by > 5 log CFU/cm(2) by 2 min, and reduced populations to undetectable levels (below 2 log CFU/cm(2)) by 5 min (P < 0.05). Similarly, OH coating on cantaloupe rinds reduced the pathogens by 3-5 log /cm(2) (P < 0.05). Washing and coating whole cantaloupes with OH reduced the three pathogens by at least 5 log and 2 log CFU/cm(2), respectively (P < 0.05). Results suggest that OH could be used as antimicrobial wash and coating to reduce LM, SAL, and EC on cantaloupes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Inositol 1,3,4,5-tetrakisphosphate as a mediator of neuronal death in ischemic hippocampus.

    Science.gov (United States)

    Tsubokawa, H; Oguro, K; Robinson, H P; Masuzawa, T; Rhee, T S; Takenawa, T; Kawai, N

    1994-03-01

    Selective death of CA1 pyramidal neurons after transient forebrain ischemia has attracted interest for its possible relation to the pathogenesis of memory deficits and dementia. Using whole cell patch-clamp recording from CA1 pyramidal neurons in hippocampal slices of gerbils after ischemia we studied the intracellular signaling mechanisms related to the phosphoinositide cycle. Intracellular application of an antibody against phosphatidylinositol 4,5-bisphosphate rescued ischemic neurons from stimulus-induced irreversible depolarization. Furthermore, application of inositol 1,3,4,5-tetrakisphosphate in normal cells caused an irreversible depolarization in response to synaptic input, which mimicked the deterioration of ischemic neurons. Depolarization of both ischemic and normal neurons in the presence of inositol 1,3,4,5-tetrakisphosphate was prevented by the addition of the Ca2+ chelator, 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetate. Application of antibody against inositol 1,4,5-triphosphate 3-kinase, which blocks formation of inositol 1,3,4,5-tetrakisphosphate, also protected against cell deterioration. Our results suggest that the vulnerability of hippocampal pyramidal neurons following ischemia is caused by a disturbed phosphoinositide cascade, with one metabolite, inositol 1,3,4,5-tetrakisphosphate, playing a key role in the induction of Ca2+ accumulation, which leads to neuronal death.

  14. Analysis and risk assessment of 4(5)-methylimidazole in brown colored foods and beverages.

    Science.gov (United States)

    Lee, Sumin; Lee, Kwang-Geun

    2016-01-01

    In this study, the 4(5)-methylimidazole (4(5)-MI) levels in various 144 brown coloured foods and beverages were determined. The brown coloured foods and beverages were 62 processed sauces, 40 coffee, 9 caramel syrups, 18 red ginseng juice and 15 Japanese apricot fruit juice. The amount of 4(5)-MI in brewed coffee (1821.3 ng/g) was the highest level among the samples. The 4(5)-MI concentration in processed sauce (47.6 ng/g) was the lowest level among the samples. The levels of 4(5)-MI in various samples were found as follows: 47.6-1748.5 ng/g in processed sauces, 64.1-1821.3 ng/g in commercial coffee, 115.5-491.9 ng/g in caramel syrups, 91.0-854.1 ng/g in red ginseng juice and 137.6-587.4 ng/g in Japanese apricot fruit juice. Based on the 4(5)-MI levels, the estimated daily intake (EDI) and chronic daily intake (CDI) were calculated. EDI and CDI of red ginseng juice was the highest among all samples, and they were 1618.6 and 1256.8 ng/kg bw/day, respectively.

  15. The elongation factor Spt4/5 regulates RNA polymerase II transcription through the nucleosome

    Science.gov (United States)

    Crickard, John B.; Lee, Jaehyoun; Lee, Tae-Hee

    2017-01-01

    Abstract RNA polymerase II (RNAPII) passes through the nucleosome in a coordinated manner, generating several intermediate nucleosomal states as it breaks and then reforms histone–DNA contacts ahead of and behind it, respectively. Several studies have defined transcription-induced nucleosome intermediates using only RNA Polymerase. However, RNAPII is decorated with elongation factors as it transcribes the genome. One such factor, Spt4/5, becomes an integral component of the elongation complex, making direct contact with the ‘jaws’ of RNAPII and nucleic acids in the transcription scaffold. We have characterized the effect of incorporating Spt4/5 into the elongation complex on transcription through the 601R nucleosome. Spt4/5 suppressed RNAPII pausing at the major H3/H4-induced arrest point, resulting in downstream re-positioning of RNAPII further into the nucleosome. Using a novel single molecule FRET system, we found that Spt4/5 affected the kinetics of DNA re-wrapping and stabilized a nucleosomal intermediate with partially unwrapped DNA behind RNAPII. Comparison of nucleosomes of different sequence polarities suggest that the strength of the DNA–histone interactions behind RNAPII specifies the Spt4/5 requirement. We propose that Spt4/5 may be important to coordinate the mechanical movement of RNAPII through the nucleosome with co-transcriptional chromatin modifications during transcription, which is affected by the strength of histone–DNA interactions. PMID:28379497

  16. One-pot Synthesis of 2-Nitro-4,5-dicyano-1H-imidazole

    Institute of Scientific and Technical Information of China (English)

    XU Cheng; BIFu-qiang; FAN Xue-zhong; LI Ji-zhen; WANG Bo-zhou; GE Zhong-xue; LIU Qing; ZHANG Guo-fang

    2011-01-01

    In the last few decades,nitroimidazoles have been investigated mostly due to their properties as antibiotics,radiosensitizers and anti-protozoans[1 -3].Recently these nitroimidazoles,such as 2,4-dinitroimidazole,1-methyl-2,4,5-trinitroimidazole and their energetic salts, have attracted renewed attention for their favorable explosive performance as well as improved safety characteristics[4,5].Because of the activity of cyano group,2-nitro-4,5-dicyano-1 H-imidazole (NDCI) could be used as an intermediate in the synthesis of novel energetic materials containing nitroimidazole moiety.NDCI has been synthesized by the procedure given by Yixin Lu and coworkers[6],where the diazotization reaction and the Sandmeyer reaction were separately achieved.NDCI was obtained by adding a solution of sodium nitrite to 2-diazo4,5-dicyanoimidazole which was generated by diazotization of 2-amino-4,5-dicyano-1H-imidazole ( ADCI ) with sodium nitrite in water-hydrochloric acid and collected by filtration.Dry 2-diazo-4,5-dicyanoimidazole was so sensitive to shock that its separation may cause explosion[7].

  17. Order of inoculation affects the success of co-invading entomopathogenic fungi.

    Science.gov (United States)

    Zamora-Macorra, E J; Guzmán-Franco, A W; Pell, J K; Alatorre-Rosas, R; Suarez-Espinoza, J

    2012-12-01

    The effect of order of inoculation of Pandora blunckii and Zoophthora radicans co-infecting Plutella xylostella (L.) (Lepidoptera: Plutellidae) was investigated. After co-inoculation, the proportion of larvae infected by either species was greatly reduced compared to when they were inoculated singly. The order of inoculation influenced the final outcome; the isolate inoculated last always killed more larvae than the isolate inoculated first.

  18. Genetic diversity of symbiotic Bradyrhizobium elkanii populations recovered from inoculated and non-inoculated Acacia mangium field trials in Brazil.

    Science.gov (United States)

    Perrineau, M M; Le Roux, C; de Faria, S M; de Carvalho Balieiro, F; Galiana, A; Prin, Y; Béna, G

    2011-07-01

    Acacia mangium is a legume tree native to Australasia. Since the eighties, it has been introduced into many tropical countries, especially in a context of industrial plantations. Many field trials have been set up to test the effects of controlled inoculation with selected symbiotic bacteria versus natural colonization with indigenous strains. In the introduction areas, A. mangium trees spontaneously nodulate with local and often ineffective bacteria. When inoculated, the persistence of inoculants and possible genetic recombination with local strains remain to be explored. The aim of this study was to describe the genetic diversity of bacteria spontaneously nodulating A. mangium in Brazil and to evaluate the persistence of selected strains used as inoculants. Three different sites, several hundred kilometers apart, were studied, with inoculated and non-inoculated plots in two of them. Seventy-nine strains were isolated from nodules and sequenced on three housekeeping genes (glnII, dnaK and recA) and one symbiotic gene (nodA). All but one of the strains belonged to the Bradyrhizobium elkanii species. A single case of housekeeping gene transfer was detected among the 79 strains, suggesting an extremely low rate of recombination within B. elkanii, whereas the nodulation gene nodA was found to be frequently transferred. The fate of the inoculant strains varied depending on the site, with a complete disappearance in one case, and persistence in another. We compared our results with the sister species Bradyrhizobium japonicum, both in terms of population genetics and inoculant strain destiny. Copyright © 2011 Elsevier GmbH. All rights reserved.

  19. Patogénesis de Listeria monocytogenes, microorganismo zoonotico emergente

    Directory of Open Access Journals (Sweden)

    Kirvis Torres

    2005-05-01

    Full Text Available Listeria monocytogenes además de ser un paradigma para la investigación inmunológica se ha convertidoen sistema modelo apropiado para el análisis de los mecanismos moleculares del parasitismo intracelularde otras bacterias. Investigadores en el área de la inmunología se interesaron en este microorganismocuando se reconoció el riesgo que representaba para la salud pública y la seguridad en la industria dealimentos. Desde mediados de los años 80’s se ha investigado la biología molecular de los marcadores devirulencia de este microorganismo, la biología celular de las interacciones de los marcadores de virulenciacon los receptores de la célula hospedero, el citoesqueleto, las vías de transducción de señales y losmecanismos de inmunidad mediada por células del hospedero. El propósito de esta revisión es describiralgunas características taxonómicas y filogenéticas de Listeria monocytogenes , la incidencia humana yanimal de varios serotipos, la fisiopatología de la infección , modelos animales y de cultivo celular utilizadospara estudios de virulencia, las poblaciones de riesgo, manifestaciones clínicas de listeriosis humana yanimal, el tratamiento, la organización genética y evolución de los determinantes de virulencia, losmecanismos empleados para interactuar con la célula hospedera, y los mecanismos para escapar de losprocesos de muerte celular y pasar de una célula infectada a otra. La información recopilada resulta degran importancia para el personal de salud, industria, consumidores y población de riesgo; razón por lacual Listeria monocytogenes es un patógeno que representa una amenaza para la salud pública mundial.

  20. Control of Listeria monocytogenes in food production plants

    Directory of Open Access Journals (Sweden)

    Dimitrijević Mirjana

    2008-01-01

    Full Text Available L. monocytogenes has been established in different plants for the production of food, including dairy plants, abattoirs, plants for the processing of fish, as well as those for the production of ready-to-eat (RTE food and this fact is being considered as the primary mechanism of food contamination with this bacteria. There is also the factor of numerous and diverse contaminated production equipment, because it has certain parts that are inaccessible for the necessary cleaning and disinfection. The temperature, position, as well as the material of the work surface are also linked to the contamination of plants with this bacteria. Investigations carried out so far have helped toward the better understanding of the manner and time of contamination of food items in the course of the production process, but there are still unresolved problems, including most certainly the biggest one - the adherence of bacteria and the creation of a biofilm, when the bacteria is in that condition more resistant to so-called stress factors which are usually used in the food industry for the purpose of decontamination of the surfaces with which foods come into contact. The control of L. monocytogenes in food production plants is possible primarily by using an integrated programme, compatible with the systems Hazard Analysis Critical Control Point (HACCP and Good Hygiene Practice (GHP, necessary in the production of food that is safe for the consumer. Essentially, the control measures that can contribute to reducing the incidence of findings of L.monocytogenes in the finished product, as well as the reducing of the level of contamination with this bacteria are linked, on the one hand, with hygiene procedures in the production process, and, on the other, with the applied technological procedures.

  1. Strain rate dependence of the tensile properties of V-(4--5%)Cr-(4--5%)Ti irradiated in EBR-II and HFBR

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Snead, L.L.; Robertson, J.P.; Rowcliffe, A.F. [Oak Ridge National Lab., TN (United States)

    1998-03-01

    Elevated temperature tensile tests performed on V-(405)Cr-(4-5)Ti indicate that the yield stress increases with increasing strain rate for irradiation and test temperatures near 200 C, and decreases with increasing strain rate for irradiation and test temperatures near 400 C. This observation is in qualitative agreement with the temperature-dependent strain rate effects observed on unirradiated specimens, and implies that some interstitial solute remains free to migrate in irradiated specimens. Additional strain rate data at different temperatures are needed.

  2. Inactivation of Listeria monocytogenes on unpackaged and vacuum-packaged chicken frankfurters using pulsed UV-light.

    Science.gov (United States)

    Keklik, N M; Demirci, A; Puri, V M

    2009-10-01

    The effectiveness of pulsed UV-light on the microbial load and quality of unpackaged and vacuum-packaged chicken frankfurters was investigated. Samples were inoculated with Listeria monocytogenes Scott A on the top surfaces, and then treated with pulsed UV-light for 5, 15, 30, 45, and 60 s at 5, 8, and 13 cm distance from the quartz window in a pulsed UV-light chamber. Log reductions (CFU/cm(2)) on unpackaged samples were between 0.3 and 1.9 after 5-s treatment at 13 cm and 60-s treatment at 5 cm, respectively. Log reductions on packaged samples ranged from 0.1 to 1.9 after 5-s treatment at 13 cm and 60-s treatment at 5 cm, respectively. The temperature changes of samples and total energy (J/cm(2)) received at each treatment condition were monitored. The extent of lipid peroxidation and the color were determined by thiobarbituric acid-reactive substances (TBARS) test and CIELAB color method, respectively. Lipid peroxidation of samples did not change significantly (P > 0.05) after mild (5-s treatment at 13 cm) and moderate (30-s treatment at 8 cm) treatments. Significant differences (P 0.05) after mild treatment. Overall, this study demonstrated that pulsed UV-light has a potential to decontaminate ready-to-eat (RTE) poultry-based food products.

  3. Carbon dioxide and nisin act synergistically on Listeria monocytogenes

    DEFF Research Database (Denmark)

    Nilsson, Lilian; Chen, Y.H.; Chikindas, M.L.

    2000-01-01

    This paper examines the synergistic action of carbon dioxide and nisin on Listeria monocytogenes Scott A wild-type and nisin-resistant (Nis(r)) cells grown in broth at 4 degrees C. Carbon dioxide extended the lag phase and decreased the specific growth rate of both strains, but to a greater degree...... for cultures in CO2. This synergism between nisin and CO2 was examined mechanistically by following the leakage of carboxyfluorescein (CF) from listerial liposomes. Carbon dioxide enhanced nisin-induced CF leakage, indicating that the synergistic action of CO2 and nisin occurs at the cytoplasmic membrane...

  4. Inhibition of Listeria monocytogenes by fatty acids and monoglycerides.

    OpenAIRE

    Wang, L. L.; Johnson, E. A.

    1992-01-01

    Fatty acids and monoglycerides were evaluated in brain heart infusion broth and in milk for antimicrobial activity against the Scott A strain of Listeria monocytogenes. C12:0, C18:3, and glyceryl monolaurate (monolaurin) had the strongest activity in brain heart infusion broth and were bactericidal at 10 to 20 micrograms/ml, whereas potassium (K)-conjugated linoleic acids and C18:2 were bactericidal at 50 to 200 micrograms/ml. C14:0, C16:0, C18:0, C18:1, glyceryl monomyristate, and glyceryl m...

  5. Genetic dissection of DivIVA functions in Listeria monocytogenes.

    Science.gov (United States)

    Kaval, Karan Gautam; Hauf, Samuel; Rismondo, Jeanine; Hahn, Birgitt; Halbedel, Sven

    2017-10-02

    DivIVA is a membrane binding protein that clusters at curved membrane regions such as the cell poles and the membrane invaginations occurring during cell division. DivIVA proteins recruit many other proteins to these subcellular sites through direct protein-protein interactions. DivIVA-dependent functions are typically associated with cell growth and division, even though species-specific differences in the spectrum of DivIVA functions and their causative interaction partners exist. DivIVA from the Gram-positive human pathogen Listeria monocytogenes has at least three different functions. In this bacterium, DivIVA is required for precise positioning of the septum at mid-cell, it contributes to secretion of autolysins required for breakdown of peptidoglycan at the septum after completion of cell division, and it is essential for flagellar motility. While the DivIVA interaction partners for control of division site selection are well-established, the proteins connecting DivIVA with autolysin secretion or swarming motility are completely unknown. We set out to identify divIVA alleles, in which these three DivIVA functions could be separated, since the question of the degree to which the three functions of L. monocytogenes DivIVA are interlinked could not be answered before. Here, we identify such alleles, and our results show that division site selection, autolysin secretion, and swarming represent three discrete pathways that are independently influenced by DivIVA. These findings provide the required basis for the identification of DivIVA interaction partners controlling autolysin secretion and swarming in the future.IMPORTANCE DivIVA of the pathogenic bacterium Listeria monocytogenes is a central scaffold protein that influences at least three different cellular processes, namely cell division, protein secretion and bacterial motility. How DivIVA coordinates these rather unrelated processes is not known. We here identify variants of L. monocytogenes DivIVA, in which

  6. Listeria monocytogenes HAZARD MANAGEMENT IN A TYPICAL PRODUCT: THE CIAUSCOLO

    Directory of Open Access Journals (Sweden)

    S Fisichella

    2013-02-01

    Full Text Available The aim of the present study is to investigate operative procedures that allow to minimize Listeria monocytogenes (L. m. hazard in the main traditional sausage of the internal areas of Marche (Italy: the Ciauscolo, that has received the quality trademark PGI. It is made from lean cuts of well mature pork that is finely minced, adding fat which give the salami his characteristic softness and flavour. It is characterized by having a very little maturing period that determine high aw levels and, for this peculiarity, it allows L. m development.

  7. Patogénesis de Listeria monocytogenes, microorganismo zoonotico emergente

    OpenAIRE

    Kirvis Torres; Sara Sierra; Raúl Poutou; Ana Carrascal; Marcela Mercado

    2005-01-01

    Listeria monocytogenes además de ser un paradigma para la investigación inmunológica se ha convertidoen sistema modelo apropiado para el análisis de los mecanismos moleculares del parasitismo intracelularde otras bacterias. Investigadores en el área de la inmunología se interesaron en este microorganismocuando se reconoció el riesgo que representaba para la salud pública y la seguridad en la industria dealimentos. Desde mediados de los años 80’s se ha investigado la biología molecular de los ...

  8. Listeria Monocytogenes' Survival in Honey and Royal Jelly and Its Detection Methods%单核细胞增生李斯特菌在蜂产品中的生存及检测

    Institute of Scientific and Technical Information of China (English)

    张红娟; 李素芳; 李白; 孙骏威; 徐伟

    2012-01-01

    Objective; Survival and proliferation of pathogenic microorganism-Listeria monocytogenes in honey and royal jelly need to be characterized to ensure food safety. Methods: Survival and proliferation of Listeria monocytogenes in honey and royal jelly were detected by cell culture, multiplex PCR and real-time PCR. The multiplex PCR was accomplished using the primers from genes of hly and 16 sRNA in matrix as the target The hly probes were labeled by FAM and TAMRA, which were used successfully to develop a real-time PCR. Honey and royal jelly inoculated by Listeria monocytogenes in high concentration were stored up to 4 W at room temperature. The pathogenic bacteria in the honey and royal jelly were cultured on a selective medium. Survival and proliferation of the pathogenic bacteria was detected by amplification of the HLY and 16 sRNA genes and fluorescence-quantitative PCR, respectively. Results; Listeria monocytogenes in the honey survived for 5 days, but they could not survive in the royal jelly. For the honey and royal jelly with artificial inoculation of Listeria monocytogenes, the detection limit without enrichment is very low(102CFU/mL). In this study, a simple method for detection of Listeria monocytogenes in honey and royal jelly has been established. It takes only 8 hours to complete the procedure. Conclusions; Listeria monocytogenes can survive for several days and hardly proliferate in honey, but they can't survive in royal jelly.%目的:为了保障蜂产品免受致病性单核细胞增生李斯特菌的威胁,对蜂产品中单核细胞增生李斯特菌进行检测.方法:采用培养和分子生物学的检测方法研究蜂产品中致病性单核细胞增生李斯特菌的污染状况.将高浓度的病原菌人工污染到蜂蜜和蜂王浆中,室温存放一定时间后,在选择性培养基上增菌培养;以毒力基因hly和16 s RNA基因为靶序列,建立双重PCR检测病原菌的方法;以5’、3’端标记FAM、TAMRA的hly基因探

  9. Recovery of Listeria monocytogenes from vacuum-sealed packages of frankfurters: comparison of the U.S. Department of Agriculture (USDA) food safety and inspection service product composite enrichment method, the USDA Agricultural Research Service (ARS) product composite rinse method, and the USDA-ARS package rinse method.

    Science.gov (United States)

    Luchansky, John B; Porto, Anna C S; Wallace, F Morgan; Call, Jeffrey E

    2002-03-01

    This study compared three methods for the recovery of Listeria monocytogenes from commercially prepared and vacuum-packaged frankfurters that were inoculated with a five-strain mixture of this pathogen at averages of 22 and 20,133 CFU per package over three trials. The presence and levels of the pathogen were determined by (i) the U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) product composite enrichment method, involving the selective enrichment of a 25-g composite of product and the subsequent plating of this product onto selective agar plates; (ii) the USDA Agricultural Research Service (ARS) product composite rinse method, involving the rinsing of a 25-g composite of product with 0.1% peptone water and the subsequent plating of a portion of the rinse fluid directly onto selective agar plates; and (iii) the USDA-ARS package rinse method, involving the use of 25 ml of 0.1% peptone water to rinse the entire contents of a package and the subsequent plating of a portion of the rinse fluid directly onto selective agar plates. For packages inoculated with 20,133 CFU. L. monocytogenes was recovered at a frequency (percentage of packages positive) of 100% by each of the three methods. The pathogen was recovered at efficiencies (percentages of recovery of L. monocytogenes) of 43 and 94% with the USDA-ARS product rinse method and the USDA-ARS package rinse method, respectively. For packages inoculated with 22 CFU, L. monocytogenes was recovered at frequencies of 17, 10, and 100% by the USDA-FSIS product composite enrichment method, the USDA-ARS product composite rinse method, and the USDA-ARS package rinse method, respectively. The pathogen was recovered at efficiencies of 20 and 95% with the USDA-ARS product composite rinse method and the USDA-ARS package rinse method, respectively. In a related study, the USDA-ARS package rinse method was the only method that detected the pathogen in 60 packages from each of five brands of frankfurters

  10. Potential Bio-Control Agent from Rhodomyrtus tomentosa against Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Grace Fiyinfoluwa Odedina

    2015-09-01

    Full Text Available Listeria monocytogenes is an important foodborne pathogen implicated in many outbreaks of listeriosis. This study aimed at screening for the potential use of Rhodomyrtus tomentosa ethanolic leaf extract as a bio-control agent against L. monocytogenes. Twenty-two L. monocytogenes isolates were checked with 16 commercial antibiotics and isolates displayed resistance to 10 antibiotics. All the tested isolates were sensitive to the extract with inhibition zones ranging from 14 to 16 mm. Minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC values ranged from 16 to 32 µg/mL and 128 to 512 µg/mL, respectively. Time-kill assay showed that the extract had remarkable bactericidal effects on L. monocytogenes. The extract at a concentration of 16 µg/mL reduced tolerance to 10% NaCl in L. monocytogenes in 4 h. Stationary phase L. monocytogenes cells were rapidly inactivated by greater than 3-log units within 30 min of contact time with R. tomentosa extract at 128 µg/mL. Electron microscopy revealed fragmentary bacteria with changes in the physical and morphological properties. Our study demonstrates the potential of the extract for further development into a bio-control agent in food to prevent the incidence of L. monocytogenes contamination.

  11. The fate of two Listeria monocytogenes serotypes in "cig kofte" at different storage temperatures.

    Science.gov (United States)

    Durmaz, Hisamettin; Sagun, Emrullah; Sancak, Hakan; Sagdic, Osman

    2007-05-01

    Cig kofte is a traditional Turkish food prepared from minced beef, bulgur, onions, garlic and varieties of spices. It is generally consumed within a few hours. However, leftovers can be kept in refrigerator or in room temperature up to 24h until they are consumed. In this study, survival and growth of two Listeria monocytogenes serotypes were investigated in cig kofte during the storage. For this purpose, the prepared samples were separately contaminated with serotypes 1/2b or 4b of L. monocytogenes at the level of 10(4)CFU/g and stored at 4°C and 21°C. L. monocytogenes colonies were counted at the beginning, 3rd, 6th, 12th and 24th hours of the storage. At 4°C, L. monocytogenes 4b significantly increased (P0.05) during the storage period. At 21°C, both L. monocytogenes 1/2b and 4b increased significantly (Pcig kofte did not inhibit the growths of L. monocytogenes serotypes during the storage. These results indicated that L. monocytogenes was able to survive and grow in cig kofte at the both storage temperatures of 4°C and 21°C and cig kofte seemed to be a suitable medium for this pathogen.

  12. Relationship between Listeria monocytogenes and Listeria spp. in seafood processing plants.

    Science.gov (United States)

    Alali, Walid Q; Schaffner, Donald W

    2013-07-01

    The objective of this study was to evaluate the relationship between prevalence of Listeria monocytogenes as an outcome and Listeria spp. as an explanatory variable by food products, food contact surfaces, and nonfood contact surfaces in seafood processing plants by using peer-reviewed published data. Nine sets of prevalence data of L. monocytogenes and Listeria spp. were collected from published studies and used for the analyses. Based on our analysis, the relationship between L. monocytogenes prevalence and Listeria spp. prevalence in food products (incoming raw materials and finish products) was significant (P = 0.04) with (low) R² = 0.36. Furthermore, Listeria spp. were not a good indicator for L. monocytogenes when testing food contact surfaces (R² = 0.10). Listeria spp. were a good indicator for L. monocytogenes only on nonfood contact surfaces (R² = 0.90). On the other hand, the presence of Listeria spp. on food contact surfaces (R² = 0.002) and nonfood contact surfaces (R² = 0.03) was not a good indicator for L. monocytogenes presence in food products. In general, prevalence of Listeria spp. does not seem to be a good indicator for L. monocytogenes prevalence in seafood processing plants.

  13. Ultra deep sequencing of Listeria monocytogenes sRNA transcriptome revealed new antisense RNAs.

    Directory of Open Access Journals (Sweden)

    Sebastian Behrens

    Full Text Available Listeria monocytogenes, a gram-positive pathogen, and causative agent of listeriosis, has become a widely used model organism for intracellular infections. Recent studies have identified small non-coding RNAs (sRNAs as important factors for regulating gene expression and pathogenicity of L. monocytogenes. Increased speed and reduced costs of high throughput sequencing (HTS techniques have made RNA sequencing (RNA-Seq the state-of-the-art method to study bacterial transcriptomes. We created a large transcriptome dataset of L. monocytogenes containing a total of 21 million reads, using the SOLiD sequencing technology. The dataset contained cDNA sequences generated from L. monocytogenes RNA collected under intracellular and extracellular condition and additionally was size fractioned into three different size ranges from 150 nt. We report here, the identification of nine new sRNAs candidates of L. monocytogenes and a reevaluation of known sRNAs of L. monocytogenes EGD-e. Automatic comparison to known sRNAs revealed a high recovery rate of 55%, which was increased to 90% by manual revision of the data. Moreover, thorough classification of known sRNAs shed further light on their possible biological functions. Interestingly among the newly identified sRNA candidates are antisense RNAs (asRNAs associated to the housekeeping genes purA, fumC and pgi and potentially their regulation, emphasizing the significance of sRNAs for metabolic adaptation in L. monocytogenes.

  14. Ultra Deep Sequencing of Listeria monocytogenes sRNA Transcriptome Revealed New Antisense RNAs

    Science.gov (United States)

    Behrens, Sebastian; Widder, Stefanie; Mannala, Gopala Krishna; Qing, Xiaoxing; Madhugiri, Ramakanth; Kefer, Nathalie; Mraheil, Mobarak Abu; Rattei, Thomas; Hain, Torsten

    2014-01-01

    Listeria monocytogenes, a gram-positive pathogen, and causative agent of listeriosis, has become a widely used model organism for intracellular infections. Recent studies have identified small non-coding RNAs (sRNAs) as important factors for regulating gene expression and pathogenicity of L. monocytogenes. Increased speed and reduced costs of high throughput sequencing (HTS) techniques have made RNA sequencing (RNA-Seq) the state-of-the-art method to study bacterial transcriptomes. We created a large transcriptome dataset of L. monocytogenes containing a total of 21 million reads, using the SOLiD sequencing technology. The dataset contained cDNA sequences generated from L. monocytogenes RNA collected under intracellular and extracellular condition and additionally was size fractioned into three different size ranges from 150 nt. We report here, the identification of nine new sRNAs candidates of L. monocytogenes and a reevaluation of known sRNAs of L. monocytogenes EGD-e. Automatic comparison to known sRNAs revealed a high recovery rate of 55%, which was increased to 90% by manual revision of the data. Moreover, thorough classification of known sRNAs shed further light on their possible biological functions. Interestingly among the newly identified sRNA candidates are antisense RNAs (asRNAs) associated to the housekeeping genes purA, fumC and pgi and potentially their regulation, emphasizing the significance of sRNAs for metabolic adaptation in L. monocytogenes. PMID:24498259

  15. Modified ibogaine fragments: synthesis and preliminary pharmacological characterization of 3-ethyl-5-phenyl-1,2,3,4,5, 6-hexahydroazepino[4,5-b]benzothiophenes.

    Science.gov (United States)

    Efange, S M; Mash, D C; Khare, A B; Ouyang, Q

    1998-11-05

    Five phenyl-substituted derivatives and analogues of 1,2,3,4,5, 6-hexahydroazepino[4,5-b]indole, 5, a major fragment of ibogaine (1), were synthesized and tested for binding to monoamine transporters, the NMDA receptor-coupled cation channel, and dopamine and opioid receptors. All five derivatives, 9 and 17a-d, displayed 8-10-fold higher affinity at the DA transporter than ibogaine and noribogaine (4). At the serotonin transporter, two compounds (9 and 17a) exhibited higher potency than ibogaine, while the rest had weaker binding affinities than the lead compound. In keeping with their structural similarity to ibogaine, all five compounds displayed weak to poor affinity for dopamine D1 and D2 receptors. However, two compounds, 17a,c, demonstrated moderate binding affinities at dopamine D3 receptors. All five compounds displayed weak to poor affinities for mu and kappa opioid receptors and for the NMDA receptor-coupled cation channel. Despite the qualitative differences, derivatives and analogues of 5may serve as useful substitutes for ibogaine.

  16. Interaction between an 8-methoxypyrimido[4',5':4,5] thieno (2,3-)quinoline-4(3H)one antitumour drug and deoxyribonucleic acid

    Indian Academy of Sciences (India)

    M Gopal; M S Shahabuddin; Sanjeev R Inamdar

    2002-12-01

    The interaction of 8-methoxypyrimido[4',5':4,5] thieno (2,3-)quinoline-4(3H)one (MPTQ) with DNA was studied by UV-Vis and fluorescenc'e spectrophotometry as well as by hydrodynamic methods. On binding to DNA, the absorption spectrum underwent bathochromic and hypochromic shifts and the fluorescence was quenched. Binding parameters, determined from spectrophotometric measurements by Scatchard analysis, indicated a binding constant of 3.56 × 106 M-1 for calf thymus DNA at ionic strength 0.01 M. Binding to the GC-rich DNA of Micrococcus lysodeikticus was stronger than the binding to calf thymus DNA at ionic strength 0.01 M. The MPTQ increased the viscosity of sonicated rod-like DNA fragments, producing a calculated length of 2.4 Å/bound MPTQ molecule. The binding of MPTQ to DNA increased the melting temperature by about 4°C. This research offers a new intercalation functional group to DNA targetted drug design.

  17. A novel DNA intercalator, butylamino-pyrimido[4',5':4,5]selenolo(2,3-b)quinoline, induces cell cycle arrest and apoptosis in leukemic cells.

    Science.gov (United States)

    Shahabuddin, M S; Nambiar, Mridula; Choudhary, Bibha; Advirao, Gopal M; Raghavan, Sathees C

    2010-02-01

    DNA intercalators are one of the most commonly used chemotherapeutic agents. Novel intercalating compounds of pyrimido[4',5':4,5]selenolo(2,3-b)quinoline series having a butylamino or piperazino group at fourth position (BPSQ and PPSQ, respectively) are studied. Our results showed that BPSQ induced cytotoxicity whereas PPSQ was cytostatic. The cytotoxicity induced by BPSQ was concentration- and time-dependent. Cell cycle analysis and tritiated thymidine assay revealed that BPSQ affects the cell cycle progression by arresting at S phase. The absence of p-histone H3 and reduction in the levels of PCNA in the cells treated with BPSQ further confirmed the cell cycle arrest. Further, annexin V staining, DNA fragmentation, nuclear condensation and changes in the expression levels of BCL2/BAD confirmed the activation of apoptosis. Activation of caspase 8 and lack of cleavage of caspase 9, caspase 3 and PARP suggest the possibility of BPSQ triggering extrinsic pathway for induction of apoptosis, which is discussed. Hence, we have identified a novel compound which would have clinical relevance in cancer chemotherapeutics.

  18. Compatibility study of trans-1,4,5,8-tetranitro-1,4,5,8-tetraazadecalin (TNAD) with some energetic components and inert materials.

    Science.gov (United States)

    Yan, Qi-Long; Xiao-Jiang, Li; La-Ying, Zhang; Ji-Zhen, Li; Hong-Li, Li; Zi-Ru, Liu

    2008-12-30

    The compatibility of trans-1,4,5,8-tetranitro-1,4,5,8-tetraazadecalin (TNAD) with some energetic components and inert materials of solid propellants was studied by using the pressure DSC method where, cyclotetramethylenetetranitroamine (HMX), cyclotrimethylenetrinitramine (RDX), 1,4-dinitropiperazine (DNP), 1.25/1-NC/NG mixture, lead 3-nitro-1,2,4-triazol-5-onate (NTO-Pb), aluminum powder (Al, particle size=13.6microm) and N-nitrodihydroxyethylaminedinitrate (DINA) were used as energetic components and polyethylene glycol (PEG), polyoxytetramethylene-co-oxyethylene (PET), addition product of hexamethylene diisocyanate and water (N-100), 2-nitrodianiline (2-NDPA), 1,3-dimethyl-1,3-diphenyl urea (C2), carbon black (C.B.), aluminum oxide (Al2O3), cupric 2,4-dihydroxy-benzoate (beta-Cu), cupric adipate (AD-Cu) and lead phthalate (phi-Pb) were used as inert materials. It was concluded that the binary systems of TNAD with NTO-Pb, RDX, PET and Al powder are compatible, and systems of TNAD with DINA and HMX are slightly sensitive, and with 2-NDPA, phi-Pb, beta-Cu, AD-Cu and Al2O3 are sensitive, and with PEG, N-100, C2 and C.B. are incompatible. The impact and friction sensitivity data of the TNAD and TNAD in combination with the other energetic materials under present study was also obtained, and there was no consequential affiliation between sensitivity and compatibility.

  19. Room-temperature fracture in V-(4-5)Cr-(4-5)Ti tensile specimens irradiated in Fusion-1 BOR-60 experiment

    Energy Technology Data Exchange (ETDEWEB)

    Gazda, J.; Meshii, M. [Northwestern Univ., Evanston, IL (United States); Tsai, H. [Argonne National Lab., IL (United States)

    1998-09-01

    Specimens of V-(4-5)Cr-(4-5)Ti alloys were irradiated to {approx}18 dpa at 320 C in the Fusion-1 capsule inserted into the BOR-60 reactor. Tensile tests at 23 C indicated dramatic yield strength increase (>300%), lack of work hardening, and minimal (<1%) total elongations. SEM analysis of fracture and side surfaces were conducted to determine reduction in are and the mode of fracture. The reduction of area was negligible. All but one specimen failed by a combination of ductile shear deformation and cleavage crack growth. Transgranular cleavage cracks were initiated by stress concentrations at the tips of the shear bands. In side-view observations, evidence was found of slip bands typically associated with dislocation channeling. No differences due to pre-irradiation heat treatment and heat-to-heat composition variations were detected. The only deviation from this behavior was found in V-4Cr-4Ti-B alloy, which failed in the grip portion by complete cleavage cracking.

  20. Synthesis of 4/5-deoxy-4/5-nucleobase derivatives of 3-O-methyl-D-chiro-inositol as potential antiviral agents.

    Science.gov (United States)

    Zhan, Tian-Rong; Ma, Yu-Dao; Fan, Pei-Hong; Ji, Mei; Lou, Hong-Xiang

    2006-10-01

    Using D-pinitol (= 3-O-methyl-D-chiro-inositol) as starting material, a concise synthesis of 4/5-deoxy-4/5-nucleobase derivatives 11-19 has been achieved. The key intermediate 9 was obtained in good yield via an epoxidation from mono-methanesulfonate of D-pinitol. The process of opening of the epoxide ring in 9 by nucleobases appeared to be regioselective in presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). All the synthesized carbocyclic nucleosides were assayed against several viruses and tumors such as HIV-1, HSV-1, and HSV-2, and lung and bladder cancer. However, only compounds 14b, 14a, 16a, 16b, and 19 showed mild inhibitory effect against human lung cancer cell lines (PG) with IC50 values ranging from 50 to 100 microM, and the other compounds did not exhibit any significant antiviral activity or cytotoxicity even at concentrations up to 200 microM.

  1. Analysis of Phosphatidylinositol 3,4,5-Trisphosphates of PTEN Expression on Mammalian Cells

    Directory of Open Access Journals (Sweden)

    Nusrat Jahan

    2013-09-01

    Full Text Available The goal of this study is to find an experimental condition which enables us to perform enzymatic studies on the cellular behavior of PTEN (phosphatase and tensine homolog through identification of molecular species of phosphatidylinositol 3,4,5- trisphosphates and their quantitative analysis in a mammalian cell line using mass spectrometry. We initially exployed a two-step extraction process using HCl for extraction of phosphatidylinositol 3,4,5-trisphosphates from two mammalian cell lines and further analyzed the extracted phosphatidylinositol 3,4,5-trisphosphates using tandem mass spectrometry for the identification of them. We finally quantified the concentration of phosphatidylinositol 3,4,5-trisphosphates using internal standard calibration. From these observation, we found that HEK 293-T cells is a good model to examine the enzymatic behavior of PTEN in a cell, and the minimum amount of phosphatidylinositol 3,4,5-trisphosphates is more than 50 pmol for quantification in a mass spectrometer. These results suggest that the well-optimized experimental conditions are required for the investigation of the cellular PTEN in terms of the catalytic mechanism and further for the detailed identification of cellular substrates

  2. Ultracool Field Brown Dwarf Candidates Selected at 4.5 microns

    CERN Document Server

    Eisenhardt, Peter R M; Stern, Daniel; Wright, Edward L; Ashby, Matthew L N; Brodwin, Mark; Brown, Michael J I; Bussmann, R S; Dey, Arjun; Ghez, A M; Glikman, Eilat; Gonzalez, Anthony H; Kirkpatrick, J Davy; Konopacky, Quinn; Mainzer, Amy; Vollbach, David; Wright, Shelley A

    2010-01-01

    We have identified a sample of cool field brown dwarf candidates using IRAC data from the Spitzer Deep, Wide-Field Survey (SDWFS). The candidates were selected from 400,000 SDWFS sources with [4.5] = 1.5 and [4.5] - [8.0] 70 pc. The reddest brown dwarf candidate (SDWFS J143356.62+351849.2) has [3.6] - [4.5]=2.24 and H - [4.5] > 5.7, redder than any published brown dwarf in these colors, and may be the first example of the elusive Y-dwarf spectral class. Models from Burrows et al. (2003) predict larger numbers of cool brown dwarfs should be found for a Chabrier (2003) mass function. Suppressing the model [4.5] flux by a factor of two, as indicated by previous work, brings the Burrows models and observations into reasonable agreement. The recently launc hed Wide-field Infrared Survey Explorer (WISE) will probe a volume ~40x larger and should find hundreds of brown dwarfs cooler than T7.

  3. Listeria monocytogenes contamination in dairy plants: evaluation of Listeria monocytogenes environmental contamination in two cheese-making plants using sheeps milk

    Directory of Open Access Journals (Sweden)

    Michela Ibba

    2013-09-01

    Full Text Available Listeria monocytogenes harbouring niches established in the processing plant support post-process contamination of dairy products made from pasteurised or thermised milk. The present study investigated L. monocytogenes environmental contamination in two sheep’s milk cheese-making plants. Persistence of contamination in the area at higher risk was also investigated. During a one-year survey 7 samplings were carried out in each dairy plant, along the production lines of Pecorino Romano and ricotta salata cheese. A total of 613 environmental samples collected from food contact and non-food contact surfaces were analysed according to ISO 11290-1:2005 standard method. Identification of the isolated strains was carried out by polymerase chain reaction. L. monocytogenes prevalence was 23.2% in dairy A and 13.1% in dairy B, respectively. The higher prevalence rate was found in the following areas: salting, products washing, packaging, ricotta salata storage and Pecorino Romano ripening rooms. L. monocytogenes was never found in the cheese-making area. The probability of observing samples positive for the presence of L. monocytogenes was asso- ciated with dairy plant, sampling area and the period of cheese-making (P<0.001. The greater persistence of contamination over time was observed in the washing, salting, and Pecorino Romano ripening areas. The control of persistent environmental contamination relies on the identification of L. monocytogenes niches within the processing environment and the prevention of harborage sites formation. The importance of strict cleaning and sanitising procedure in controlling L. monocytogenes environmental contamination is confirmed by the lower level of contamination observed after these procedures were correctly implemented.

  4. GERMINATION OF GRASSES DUE TO INOCULATION DIAZOTROPHIC BACTERIA

    Directory of Open Access Journals (Sweden)

    C. D. A. Moreira

    2014-07-01

    Full Text Available The germination of forage grasses suffers from numbness and a natural tendency to low quality. The use of microorganisms inoculated in seeds with the purpose of increasing and meet the demand of some nutrient has been shown to be efficient, but the role of the microorganism in germination and rate of force is still unknown. Therefore the goal as study was to evaluate the germination rate of seeds of three cultivars of Brachiaria brizantha CV. Marandu, b., b. brizantha CV. Xaraés and b. humidícola cv Tupi and a cultivar of millet, P. hybrid cv Massai depending on the bacterium Azospirillum brasilense diazotrofic inoculation (nitrogen-fixing. Germination test was used in seed dispersal to assess the effect of first count (VPC in the treatments with and without inoculation. It was done also conducted further tests of electrical conductivity, weight of thousand seeds and water content. The delineation used was randomized entirely (DIC and the statistical analysis carried out through the analysis of variance and comparison of means using the Tukey test, the 5% probability. Massai grass seeds have the highest rate of force of first count in both treatments. Inoculation of bacterium Azospirillum brasilense did not affect the values of force of first count on seeds of the cultivars Marandu, Xaraés, Tupi and Massai. The seeds of the massai have higher germination speed relative the other cultivars evaluated when inoculated.

  5. Plant growth-promoting bacteria as inoculants in agricultural soils.

    Science.gov (United States)

    Souza, Rocheli de; Ambrosini, Adriana; Passaglia, Luciane M P

    2015-12-01

    Plant-microbe interactions in the rhizosphere are the determinants of plant health, productivity and soil fertility. Plant growth-promoting bacteria (PGPB) are bacteria that can enhance plant growth and protect plants from disease and abiotic stresses through a wide variety of mechanisms; those that establish close associations with plants, such as the endophytes, could be more successful in plant growth promotion. Several important bacterial characteristics, such as biological nitrogen fixation, phosphate solubilization, ACC deaminase activity, and production of siderophores and phytohormones, can be assessed as plant growth promotion (PGP) traits. Bacterial inoculants can contribute to increase agronomic efficiency by reducing production costs and environmental pollution, once the use of chemical fertilizers can be reduced or eliminated if the inoculants are efficient. For bacterial inoculants to obtain success in improving plant growth and productivity, several processes involved can influence the efficiency of inoculation, as for example the exudation by plant roots, the bacterial colonization in the roots, and soil health. This review presents an overview of the importance of soil-plant-microbe interactions to the development of efficient inoculants, once PGPB are extensively studied microorganisms, representing a very diverse group of easily accessible beneficial bacteria.

  6. Plant growth-promoting bacteria as inoculants in agricultural soils

    Directory of Open Access Journals (Sweden)

    Rocheli de Souza

    2015-01-01

    Full Text Available AbstractPlant-microbe interactions in the rhizosphere are the determinants of plant health, productivity and soil fertility. Plant growth-promoting bacteria (PGPB are bacteria that can enhance plant growth and protect plants from disease and abiotic stresses through a wide variety of mechanisms; those that establish close associations with plants, such as the endophytes, could be more successful in plant growth promotion. Several important bacterial characteristics, such as biological nitrogen fixation, phosphate solubilization, ACC deaminase activity, and production of siderophores and phytohormones, can be assessed as plant growth promotion (PGP traits. Bacterial inoculants can contribute to increase agronomic efficiency by reducing production costs and environmental pollution, once the use of chemical fertilizers can be reduced or eliminated if the inoculants are efficient. For bacterial inoculants to obtain success in improving plant growth and productivity, several processes involved can influence the efficiency of inoculation, as for example the exudation by plant roots, the bacterial colonization in the roots, and soil health. This review presents an overview of the importance of soil-plant-microbe interactions to the development of efficient inoculants, once PGPB are extensively studied microorganisms, representing a very diverse group of easily accessible beneficial bacteria.

  7. MHC class Jb-restricted cell responses to Listeria monocytogenes infection.

    Science.gov (United States)

    Kerksiek, K M; Pamer, E G

    1999-12-01

    Murine infection with Listeria monocytogenes induces CD8+ T cell responses specific for bacterial peptides that are presented on the infected cell surface by MHC class Ia and MHC class Ib molecules. We have used MHC tetramers to demonstrate that CD8+ T cells restricted by the H2-M3 MHC class Ib molecules constitute a substantial portion of the T cell response to L. monocytogenes infection. The in vivo size and kinetics of MHC class Ib-restricted T cell populations suggests that they play a prominent role in bacterial clearance following primary L. monocytogenes infection.

  8. Listeria monocytogenes in poultry and poultry products: Epidemiological investigations in seven Danish abattoirs

    DEFF Research Database (Denmark)

    Ojeniyi, B.; Wegener, Henrik Caspar; Jensen, N.E.

    1996-01-01

    abattoirs including poultry processing line samples, and final products were also examined for L. monocytogenes. Listeria monocytogenes was isolated in 0 . 3% to 18 . 7% of the samples collected in the different abattoirs. Epidemiological typing of 247 L. monocytogenes isolates, including serotyping, phage...... typing, pulsed-field gel electrophoresis and ribotyping revealed 62 different clones. Based upon typability and discriminatory power, DNA typing methods used were found equally suitable as epidemiological markers. Serotyping and phage typing were not found useful as epidemiological markers for poultry...

  9. Sigma B Contributes to PrfA-Mediated Virulence in Listeria monocytogenes

    OpenAIRE

    Nadon, Celine A.; Bowen, Barbara M.; Wiedmann, Martin; Boor, Kathryn J.

    2002-01-01

    Transcription of the Listeria monocytogenes positive regulatory factor A protein (PrfA) is initiated from either of two promoters immediately upstream of prfA (prfAp1 and prfAp2) or from the upstream plcA promoter. We demonstrate that prfAp2 is a functional σB-dependent promoter and that a sigB deletion mutation affects the virulence phenotype of L. monocytogenes. Thus, the alternative sigma factor σB contributes to virulence in L. monocytogenes.

  10. Incidence and characterization of Listeria monocytogenes in foods available in Taiwan.

    OpenAIRE

    Wong, H. C.; Chao, W L; Lee, S. J.

    1990-01-01

    A variety of foods were examined for the incidence of Listeria monocytogenes, and the bacterial isolates were further characterized. L. monocytogenes was selected on LiCl-phenylethanol-moxalactam agar after enrichments and identified by several biochemical, mobility, and CAMP tests. L. monocytogenes was isolated from 58.8% of pork samples, 50% of chicken carcasses, 38% of turkey parts, 34% of frozen semiready foods, 24% of beef steaks, 12.2% of vegetables, 10.5% of seafoods, and 4.4% of froze...

  11. Listeria monocytogenes Infection in a Sugar Glider (Petaurus breviceps) - New Mexico, 2011.

    Science.gov (United States)

    Nichols, M; Takacs, N; Ragsdale, J; Levenson, D; Marquez, C; Roache, K; Tarr, C L

    2015-06-01

    Listeria monocytogenes is a Gram-positive, facultative anaerobic, rod-shaped bacterium that can infect and cause disease in many species. In this case report, we describe a case of L. monocytogenes infection causing sepsis in a sugar glider (Petaurus breviceps). The sugar glider consumed a varied diet consisting of human food items, including cantaloupe. A nationwide outbreak of L. monocytogenes foodborne illness associated with cantaloupes occurred simultaneously with this incident case. In this case, the bacterial strains from the outbreak and glider were genetically distinct. Although rare, veterinarians should be aware of the emergence of foodborne pathogens' ability to infect exotic animals residing in domestic environments.

  12. Synthesis of N-Aryl-4,5,6,7-tetrahydroindoles

    Energy Technology Data Exchange (ETDEWEB)

    Lee, In Sook Han; Kwon, Min Jin; Lee, Chang Kiu [Kangwon National University, Chuncheon (Korea, Republic of)

    2012-01-15

    N-aryl-4,5,6,7-tetrahydroindoles were prepared in moderate to good yields from cyclohexane-1,3-dione in three steps. Indole, unlike pyrrole, undergoes electrophilic substitution at C-3. For example, a Vilsmeier reaction of indole gives 3-formylindole exclusively. On the other hand, the same reaction with pyrrole produces 2-formylpyrrole. If the introduction of a nucleophile at the C-2 of indole is desired, 4,5,6,7-tetrahydroindole should be employed as a starting material. An introduction of the substitution and a subsequent dehydrogenation of the tetrahydroindole should be carried out to complete the synthesis of the 2-substituted indole. For such purpose we previously reported the synthesis of 5-substituted 4,5,6,7-tetrahydroindoles from cyclohexanones with suitable substituents at 4-position of the cyclic ketone.

  13. Decreased plasma neurotrophin-4/5 levels in bipolar disorder patients in mania

    Directory of Open Access Journals (Sweden)

    Izabela G. Barbosa

    2014-12-01

    Full Text Available Objective: To evaluate two poorly explored neurotrophins (NT, NT-3 and NT-4/5, in bipolar disorder (BD. Methods: Forty patients with type I BD (18 in remission and 22 in mania and 25 healthy controls matched for age, gender, and educational attainment were enrolled in this study. All subjects were assessed by the Mini-International Neuropsychiatric Interview; the Young Mania Rating Scale and the Hamilton Depression Rating Scale were used to evaluate severity of symptoms in BD patients. Plasma levels of NT-3 and NT-4/5 were measured by enzyme-linked immunosorbent assay (ELISA. Results: BD patients in mania presented decreased NT-4/5 plasma levels in comparison with controls (p < 0.05. There were no significant differences in NT-3 plasma levels between BD patients and controls. Conclusion: These findings corroborate the view that neurotrophin dysfunction is associated with mood states in patients with BD.

  14. Bacteriophage predation promotes serovar diversification in Listeria monocytogenes.

    Science.gov (United States)

    Eugster, Marcel R; Morax, Laurent S; Hüls, Vanessa J; Huwiler, Simona G; Leclercq, Alexandre; Lecuit, Marc; Loessner, Martin J

    2015-07-01

    Listeria monocytogenes is a bacterial pathogen classified into distinct serovars (SVs) based on somatic and flagellar antigens. To correlate phenotype with genetic variation, we analyzed the wall teichoic acid (WTA) glycosylation genes of SV 1/2, 3 and 7 strains, which differ in decoration of the ribitol-phosphate backbone with N-acetylglucosamine (GlcNAc) and/or rhamnose. Inactivation of lmo1080 or the dTDP-l-rhamnose biosynthesis genes rmlACBD (lmo1081-1084) resulted in loss of rhamnose, whereas disruption of lmo1079 led to GlcNAc deficiency. We found that all SV 3 and 7 strains actually originate from a SV 1/2 background, as a result of small mutations in WTA rhamnosylation and/or GlcNAcylation genes. Genetic complementation of different SV 3 and 7 isolates using intact alleles fully restored a characteristic SV 1/2 WTA carbohydrate pattern, including antisera reactions and phage adsorption. Intriguingly, phage-resistant L. monocytogenes EGDe (SV 1/2a) isolates featured the same glycosylation gene mutations and were serotyped as SV 3 or 7 respectively. Again, genetic complementation restored both carbohydrate antigens and phage susceptibility. Taken together, our data demonstrate that L. monocytogenes SV 3 and 7 originate from point mutations in glycosylation genes, and we show that phage predation represents a major driving force for serovar diversification and evolution of L. monocytogenes.

  15. Identification of Listeria monocytogenes on Green Mussels and Cockle Shell

    Directory of Open Access Journals (Sweden)

    Winiati Puji Rahayu

    2017-02-01

    Full Text Available AbstractGreen mussel (Perna viridis and cockle shell (Anadara granosa are one of many sources of animal protein which is many cultivated in Indonesia because their price is relatively affordable. This study was conducted to identify the presence of Listeria monocytogenes in 27 samples of green mussels and 3 samples of cockle shells using real-time Polymerase Chain Reaction (real-time PCR and biochemical methods. The target gene for amplification in real-time PCR was an hlyA gene because this gene was a determinant of virulence genes that produce listeriolysin O. Primers used in this study were forward primer DG69 (GTG CCG GGT AAA AGA CCA TA and reverse primer DG74 (CGC CAC TGA GAT ACT AT and fluorescence signals indicator using SYBR Green I. The results of analysis using real-time PCR were negative Listeria monocytogenes in all samples, while using biochemical methods there was one of 30 samples contaminated by Listeria welshimeri.

  16. ASSESSMENT OF ACTION OF DISINFECTANTS AGAINST LISTERIA MONOCYTOGENES BIOFILMS

    Directory of Open Access Journals (Sweden)

    T. K. CABEÇA

    2008-12-01

    Full Text Available

    The purpose of this study was to assess the action of various disinfectants used in food industry against biofilm cells of Listeria monocytogenes formed on stainless steel surfaces during 24, 72 and 120 hours. Numbers of viable biofilm cells decreased after treatment with all the tested disinfectants (iodine, biguanide, quaternary ammonium compounds, peracetic acid and sodium hypochlorite. Sodium hypochlorite was the most effective disinfectant against the biofilm cells, while biguanide and iodine were the least. Scanning electron microscopy observations demonstrated attached cells on stainless steel surfaces after treatment with all the disinfectants. These observations showed that microorganisms were not completely removed from stainless steel surfaces after treatment with the disinfectants, however, the attachment did not means the viability of remaining cells. The biofilm age in hours (24, 72 and 120 had no apparent influence on resistance of microbiological cells to the disinfectants under study. In conclusion biofilm cells of L. monocytogenes can withstand disinfectants action.

  17. Feasibility and outcomes of intravenous thrombolysis 3-4.5 hours after stroke in Chinese patients.

    Science.gov (United States)

    Xu, Zhi-Peng; Li, Hong-Hua; Li, Ya-Hong; Zhang, Yong; Wu, Qiang; Lin, Lang

    2014-05-01

    The time window for intravenous (IV) recombinant tissue plasminogen activator (rt-PA) treatment in acute ischemic stroke (AIS) patients has been extended to 4.5 hours. But little is known about the safety and efficacy of IV rt-PA treatment in the 3-4.5 hour time window in Chinese patients with AIS. A total of 119 patients who were treated with standard IV rt-PA therapy within 4.5 hours after symptom onset were included in this study: 85 were treated within 0-3 hours and 34 were treated within 3-4.5 hours. Favorable outcome was defined as a modified Rankin scale (mRS) score of 0-1 at 6 months. The safety of IV rt-PA treatment was assessed by the rate of mortality, symptomatic intracerebral hemorrhage (SICH) and other common complications. There were no significant differences in SICH rates (2.94% versus 2.35%; p=0.85) at 24-36 hours, mortality (5.88% versus 3.53%; p=0.56), other complications (14.71% versus 11.76%; p=0.66), National Institutes of Health Stroke Scale (NIHSS) score improvement at 24 hours (41.18% versus 45.88%; p=0.64) and favorable mRS at 6 months (52.94% versus 54.12%; p=0.91) between the two time window groups. Multivariate analysis showed that advanced age, lower admission NIHSS score and shorter time from symptom onset to treatment were associated with a favorable clinical outcome. This finding showed an additional 29% of patients received IV rt-PA because of the treatment window expansion to 4.5 hours. IV rt-PA was feasible and safe for treating AIS patients in the 3-4.5 hour time window in our Chinese population.

  18. A new calmodulin-binding motif for inositol 1,4,5-trisphosphate 3-kinase regulation.

    Science.gov (United States)

    Franco-Echevarría, Elsa; Baños-Sanz, Jose I; Monterroso, Begoña; Round, Adam; Sanz-Aparicio, Julia; González, Beatriz

    2014-11-01

    IP3-3K [Ins(1,4,5)P3 3-kinase] is a key enzyme that catalyses the synthesis of Ins(1,3,4,5)P4, using Ins(1,4,5)P3 and ATP as substrates. Both inositides, substrate and product, present crucial roles in the cell. Ins(1,4,5)P3 is a key point in Ca2+ metabolism that promotes Ca2+ release from intracellular stores and together with Ins(1,3,4,5)P4 regulates Ca2+ homoeostasis. In addition, Ins(1,3,4,5)P4 is involved in immune cell development. It has been proved that Ca2+/CaM (calmodulin) regulates the activity of IP3-3K, via direct interaction between both enzymes. Although we have extensive structural knowledge of the kinase domains of the three IP3-3K isoforms, no structural information is available about the interaction between IP3-3K and Ca2+/CaM. In the present paper we describe the crystal structure of the complex between human Ca2+/CaM and the CaM-binding region of human IP3-3K isoform A (residues 158-183) and propose a model for a complex including the kinase domain. The structure obtained allowed us to identify all of the key residues involved in the interaction, which have been evaluated by site-directed mutagenesis, pull-down and fluorescence anisotropy experiments. The results allowed the identification of a new CaM-binding motif, expanding our knowledge about how CaM interacts with its partners.

  19. PtdIns(4,5)P2 signaling regulates ATG14 and autophagy.

    Science.gov (United States)

    Tan, Xiaojun; Thapa, Narendra; Liao, Yihan; Choi, Suyong; Anderson, Richard A

    2016-09-27

    Autophagy is a regulated self-digestion pathway with fundamental roles in cell homeostasis and diseases. Autophagy is regulated by coordinated actions of a series of autophagy-related (ATG) proteins. The Barkor/ATG14(L)-VPS34 (a class III phosphatidylinositol 3-kinase) complex and its product phosphatidylinositol 3-phosphate [PtdIns(3)P] play key roles in autophagy initiation. ATG14 contains a C-terminal Barkor/ATG14(L) autophagosome-targeting sequence (BATS) domain that senses the curvature of PtdIns(3)P-containing membrane. The BATS domain also strongly binds PtdIns(4,5)P2, but the functional significance has been unclear. Here we show that ATG14 specifically interacts with type Iγ PIP kinase isoform 5 (PIPKIγi5), an enzyme that generates PtdIns(4,5)P2 in mammalian cells. Autophagosomes have associated PIPKIγi5 and PtdIns(4,5)P2 that are colocalized with late endosomes and the endoplasmic reticulum. PtdIns(4,5)P2 generation at these sites requires PIPKIγi5. Loss of PIPKIγi5 results in a loss of ATG14, UV irradiation resistance-associated gene, and Beclin 1 and a block of autophagy. PtdIns(4,5)P2 binding to the ATG14-BATS domain regulates ATG14 interaction with VPS34 and Beclin 1, and thus plays a key role in ATG14 complex assembly and autophagy initiation. This study identifies an unexpected role for PtdIns(4,5)P2 signaling in the regulation of ATG14 complex and autophagy.

  20. Molecular Serotyping and Pathogenic Potential of Listeria monocytogenes Isolated from Milk and Milk Products in Tamil Nadu, India.

    Science.gov (United States)

    Karthikeyan, Raman; Gunasekaran, Paramasamy; Rajendhran, Jeyaprakash

    2015-06-01

    Listeria monocytogenes, an important bacterial pathogen, is responsible for foodborne illnesses worldwide. Examination of food samples for the presence of L. monocytogenes and assessment of their pathogenicity is usually an effective strategy in the prevention of listeriosis. In the present study, we have tested 307 samples of milk and milk products from various places in Tamil Nadu, India for the presence of L. monocytogenes using ISO 11290 and U.S. Food and Drug Administration Bacteriological Analytical Manual methods. 16S rDNA sequencing and duplex polymerase chain reaction (PCR) analysis for prs and iap genes were used to identify L. monocytogenes at the species level. Fifteen of the 307 samples screen tested positive for L. monocytogenes. Molecular serotyping of the L. monocytogenes isolates by multiplex PCR revealed the predominance of the serogroups 1/2a and 4b. Fourteen of the 15 isolates contained all the virulence genes (inlA, inlB, hlyA, and plcA) screened for using multiplex PCR. Only one isolate of L. monocytogenes was negative for the plcA gene and in vitro phosphatidylinositol-phospholipase C activity. L. monocytogenes strains that belong to the serogroup 4b exhibited higher nematocidal activity against Caenorhabditis elegans than the serogroup 1/2a. Worms infected with L. monocytogenes were symptomatic with aberrant contraction of body muscles, loss of pharyngeal pumping, and decreased locomotion, which highlights the pathogenic potential of the L. monocytogenes isolates.