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Deng X, Tang S, Wu Q, Tian J, Riley WW, Chen Z. Inactivation of Vibrio parahaemolyticus by antimicrobial photodynamic technology using methylene blue. J Sci Food Agric 2016; 96:1601-1608. [PMID: 25989459 DOI: 10.1002/jsfa.7261] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 03/30/2015] [Accepted: 05/14/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND Vibrio parahaemolyticus is the leading causative pathogen of gastroenteritis often related to contaminated seafood. Photodynamic inactivation has been recently proposed as a strategy for killing cells and viruses. The objective of this study was to verify the bactericidal effects caused by photodynamic inactivation using methylene blue (MB) over V. parahaemolyticus via flow cytometry, agarose gel electrophoresis and sodium dodecyl sulfate polyacrylamide gel electrophoresis. Vibrio parahaemolyticus counts were determined using the most probable number method. A scanning electron microscope and a transmission electron microscope were employed to intuitively analyze internal and external cell structure. RESULTS Combination of MB and laser treatment significantly inhibited the growth of V. parahaemolyticus. The inactivation rate of V. parahaemolyticus was >99.99% and its counts were reduced by 5 log10 in the presence of 0.05 mg mL(-1) MB when illuminated with visible light (power density 200 mW cm(-2)) for 25 min. All inactivated cells showed morphological changes, leakage of cytoplasm and degradation of protein and DNA. CONCLUSION Results from this study indicated that photodynamic technology using MB produced significant inactivation of V. parahaemolyticus mainly brought about by the degradation of protein and DNA.
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Affiliation(s)
- Xi Deng
- Department of Food Science and Engineering, Jinan University, Guangzhou, 510632, China
| | - Shuze Tang
- Department of Food Science and Engineering, Jinan University, Guangzhou, 510632, China
| | - Qian Wu
- Department of Food Science and Engineering, Jinan University, Guangzhou, 510632, China
| | - Juan Tian
- Department of Food Science, South China Agricultural University, Guangzhou, 510642, China
| | - William W Riley
- Department of Food Science and Engineering, Jinan University, Guangzhou, 510632, China
| | - Zhenqiang Chen
- Department of Photoelectrical Engineering, Jinan University, Guangzhou, 510632, China
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Urmersbach S, Aho T, Alter T, Hassan SS, Autio R, Huehn S. Changes in global gene expression of Vibrio parahaemolyticus induced by cold- and heat-stress. BMC Microbiol 2015; 15:229. [PMID: 26498286 PMCID: PMC4618957 DOI: 10.1186/s12866-015-0565-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 10/12/2015] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Vibrio (V.) parahaemolyticus causes seafood-borne gastro-intestinal bacterial infections in humans worldwide. It is widely found in marine environments and is isolated frequently from seawater, estuarine waters, sediments and raw or insufficiently cooked seafood. Throughout the food chain, V. parahaemolyticus encounters different temperature conditions that might alter metabolism and pathogenicity of the bacterium. In this study, we performed gene expression profiling of V. parahaemolyticus RIMD 2210633 after exposure to 4, 15, 20, 37 and 42 °C to describe the cold and heat shock response. METHODS Gene expression profiles of V. parahaemolyticus RIMD 2210633 after exposure to 4, 15, 20, 37 and 42 °C were investigated via microarray. Gene expression values and RT-qPCR experiments were compared by plotting the log2 values. Moreover, volcano plots of microarray data were calculated to visualize the distribution of differentially expressed genes at individual temperatures and to assess hybridization qualities and comparability of data. Finally, enriched terms were searched in annotations as well as functional-related gene categories using the Database for Annotation, Visualization and Integrated Discovery. RESULTS Analysis of 37 °C normalised transcriptomics data resulted in differential expression of 19 genes at 20 °C, 193 genes at 4 °C, 625 genes at 42 °C and 638 genes at 15 °C. Thus, the largest number of significantly expressed genes was observed at 15 and 42 °C with 13.3 and 13%, respectively. Genes of many functional categories were highly regulated even at lower temperatures. Virulence associated genes (tdh1, tdh2, toxR, toxS, vopC, T6SS-1, T6SS-2) remained mostly unaffected by heat or cold stress. CONCLUSION Along with folding and temperature shock depending systems, an overall temperature-dependent regulation of expression could be shown. Particularly the energy metabolism was affected by changed temperatures. Whole-genome gene expression studies of food related pathogens such as V. parahaemolyticus reveal how these pathogens react to stress impacts to predict its behaviour under conditions like storage and transport.
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Affiliation(s)
- Sara Urmersbach
- Institute of Food Hygiene, Freie Universität Berlin, Berlin, Germany.
| | - Tommi Aho
- Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland.
| | - Thomas Alter
- Institute of Food Hygiene, Freie Universität Berlin, Berlin, Germany.
| | - Syeda Sakira Hassan
- Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland.
- Department of Signal Processing, Tampere University of Technology, Tampere, Finland.
| | - Reija Autio
- Department of Signal Processing, Tampere University of Technology, Tampere, Finland.
- School of Health Sciences, University of Tampere, Tampere, Finland.
| | - Stephan Huehn
- Institute of Food Hygiene, Freie Universität Berlin, Berlin, Germany.
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Fernandez-Piquer J, Bowman JP, Ross T, Tamplin ML. Predictive models for the effect of storage temperature on Vibrio parahaemolyticus viability and counts of total viable bacteria in Pacific oysters (Crassostrea gigas). Appl Environ Microbiol 2011; 77:8687-95. [PMID: 22003032 PMCID: PMC3233097 DOI: 10.1128/aem.05568-11] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 10/07/2011] [Indexed: 11/20/2022] Open
Abstract
Vibrio parahaemolyticus is an indigenous bacterium of marine environments. It accumulates in oysters and may reach levels that cause human illness when postharvest temperatures are not properly controlled and oysters are consumed raw or undercooked. Predictive models were produced by injecting Pacific oysters (Crassostrea gigas) with a cocktail of V. parahaemolyticus strains, measuring viability rates at storage temperatures from 3.6 to 30.4°C, and fitting the data to a model to obtain parameter estimates. The models were evaluated with Pacific and Sydney Rock oysters (Saccostrea glomerata) containing natural populations of V. parahaemolyticus. V. parahaemolyticus viability was measured by direct plating samples on thiosulfate-citrate-bile salts-sucrose (TCBS) agar for injected oysters and by most probable number (MPN)-PCR for oysters containing natural populations. In parallel, total viable bacterial counts (TVC) were measured by direct plating on marine agar. Growth/inactivation rates for V. parahaemolyticus were -0.006, -0.004, -0.005, -0.003, 0.030, 0.075, 0.095, and 0.282 log₁₀ CFU/h at 3.6, 6.2, 9.6, 12.6, 18.4, 20.0, 25.7, and 30.4°C, respectively. The growth rates for TVC were 0.015, 0.023, 0.016, 0.048, 0.055, 0.071, 0.133, and 0.135 log₁₀ CFU/h at 3.6, 6.2, 9.3, 14.9, 18.4, 20.0, 25.7, and 30.4°C, respectively. Square root and Arrhenius-type secondary models were generated for V. parahaemolyticus growth and inactivation kinetic data, respectively. A square root model was produced for TVC growth. Evaluation studies showed that predictive growth for V. parahaemolyticus and TVC were "fail safe." The models can assist oyster companies and regulators in implementing management strategies to minimize V. parahaemolyticus risk and enhancing product quality in supply chains.
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Affiliation(s)
- Judith Fernandez-Piquer
- Australian Seafood Cooperative Research Centre, Box 26, Mark Oliphant Building, Science Park Adelaide, Adelaide, South Australia, Australia, and Tasmanian Institute of Agricultural Research, University of Tasmania, Private Bag 54, Hobart, Tasmania, Australia
| | - John P. Bowman
- Australian Seafood Cooperative Research Centre, Box 26, Mark Oliphant Building, Science Park Adelaide, Adelaide, South Australia, Australia, and Tasmanian Institute of Agricultural Research, University of Tasmania, Private Bag 54, Hobart, Tasmania, Australia
| | - Tom Ross
- Australian Seafood Cooperative Research Centre, Box 26, Mark Oliphant Building, Science Park Adelaide, Adelaide, South Australia, Australia, and Tasmanian Institute of Agricultural Research, University of Tasmania, Private Bag 54, Hobart, Tasmania, Australia
| | - Mark L. Tamplin
- Australian Seafood Cooperative Research Centre, Box 26, Mark Oliphant Building, Science Park Adelaide, Adelaide, South Australia, Australia, and Tasmanian Institute of Agricultural Research, University of Tasmania, Private Bag 54, Hobart, Tasmania, Australia
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Kim TY, Park SS, Kim SJ, Cho SY. A study of bactericidal effect and optimization of pathogenic bacteria using TiO2 photocatalyst. J Nanosci Nanotechnol 2011; 11:1551-1554. [PMID: 21456234 DOI: 10.1166/jnn.2011.3339] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The photocatalytic degradation of Salmonella choleraesuis subsp. and Vibrio parahaemolyticus in water by TiO2 catalysts was investigated in a batch reactor. After 30 min of irradiation with UV light in the presence of 1 mg/ml of TiO2, death ratio of S. choleraesuis subsp. and V. parahaemolyticus was 60% and 83%, respectively. And complete killing of the cells was achieved after 3 h of illumination in the presence of TiO2. We established the response surface methodology to investigate the effect of principal parameters on the pathogenic bacteria sterilization such as TiO2 concentration, pH and temperature. By applying response surface analysis to the bactericidal effect of S. almonella choleraesuis subsp. and V. parahaemolyticus, we found that the cell death ratio was influenced significantly by the first order term of TiO2 concentration.
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Affiliation(s)
- Tae-Young Kim
- Department of Environmental Engineering, Chonnam National University, Gwangju 500-757, Korea
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Ben Abdallah F, Bakhrouf A, Ayed A, Kallel H. Alterations of outer membrane proteins and virulence genes expression in gamma-irradiated Vibrio parahaemolyticus and Vibrio alginolyticus. Foodborne Pathog Dis 2010; 6:1171-6. [PMID: 19735197 DOI: 10.1089/fpd.2009.0331] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Gamma-irradiation technology sterilizes microorganisms and thereby prevents decay and improves the safety and shelf stability of food products. In this study we treated the foodborne pathogens Vibrio parahaemolyticus and Vibrio alginolyticus with gamma-irradiation (0.5 kGy) to evaluate their adaptative response. Outer membrane protein patterns of irradiated bacteria were found altered when analyzed by sodium dodecyl sulphate polyacrylamide gel electrophoresis. These modifications were manifested by the appearance and/or disappearance of bands as well as in the expression level of certain proteins. In addition, we searched for the presence of eight Vibrio cholerae virulence genes, toxR, toxS, toxRS, ctxA, zot, ace, toxT, and virulence pathogenicity island (VPI), in the genome of investigated strains. The expression of toxR, toxS, VPI, and ace genes in gamma-irradiated bacteria, studied by reverse transcriptase polymerase chain reaction, was altered. These variations were manifested by an increase and/or a decrease in the expression level of tested virulence genes.
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Affiliation(s)
- Fethi Ben Abdallah
- Laboratoire d'Analyse, Traitement et Valorisation des Polluants de l'Environnement et des Produits, Faculté de Pharmacie, Monastir, Tunisia.
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Nola M, Matchim AGS, Mobili OB, Nougang M, Krier F, Chihib NE, Hornez JP, Njiné T. Photoinactivation of Staphylococcus aureus and Vibrio parahaemolyticus in the model aquatic microcosm: effect of light intensity and dissolved biodegradable organic compound. Water Sci Technol 2010; 62:1775-1783. [PMID: 20962392 DOI: 10.2166/wst.2010.521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The impact of light (1,000 × 100,000 lx) on the inactivation of S. aureus and V. parahaemolyticus has been assessed under different concentrations of dissolved biodegradable organic compound (BOC) at pH 7.0. First, a gradual decrease in the number of cultivable cells was observed. Secondly, a cell reactivation was observed and it was marked in the absence of BOC. In the absence of BOC, the lowest value of cell inhibition rate (CIR) during the first 3 h was 0.138 h(-1) for S. aureus and 0.218 h(-1) for V. parahaemolyticus. In the presence of 10,100 and 1,000 mg/l of BOC, it was 0.196 h(-1), 0.243 h(-1) and 0.257 h(-1) for S. aureus respectively, and 0.285 h(-1), 0.306 h(-1) and 0.409 h(-1) for V. parahaemolyticus respectively. The CIRs values of each bacterial species significantly varied (P<0.001) with the changes in BOC concentration. In most cases, no significant difference was noted in the CIRs of both species when they were under the same light intensity and BOC. Nevertheless, it seems important to consider the impact of dissolved BOC during the treatment of bacterial polluted water.
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Affiliation(s)
- Moïse Nola
- Laboratory of General Biology, University of Yaounde 1, Yaounde, Cameroon.
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Kim TY, Park KH, Rho SG, Kim SJ, Cho SY. Bactericidal effect of TiO2 on the selected Vibrio parahaemolyticus and optimization using response surface methodology. J Nanosci Nanotechnol 2007; 7:3709-3712. [PMID: 18047042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In this work, the bactericidal effect of TiO2 on selected typical food pathogenic bacteria, Vibrio parahaemolyticus was studied. V parahaemolyticus is an important pathogen of humans and aqua-cultured animals. We established the response surface methodology (Box-Behnken Design) to investigate the effect of principal parameters on the cell sterilization such as TiO2 concentration, UV illumination time, temperature, and pH. The sterilization rate reached maximum value at the TiO2 concentration of 1.0 mg/ml. During irradiation under the time of 30 min with UV light with the 1g-TiO2/l, the sterilization rate was greater than 85%, and 99% or more cell lost their viability with 3 hours of irradiation. Sterilization rate of the cell increased with decrease in the pH and temperature.
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Affiliation(s)
- Tae-Young Kim
- Department of Environmental Engineering, Chonnam National University, Gwangju 500-757, Korea
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Wong MS, Chu WC, Sun DS, Huang HS, Chen JH, Tsai PJ, Lin NT, Yu MS, Hsu SF, Wang SL, Chang HH. Visible-light-induced bactericidal activity of a nitrogen-doped titanium photocatalyst against human pathogens. Appl Environ Microbiol 2006; 72:6111-6. [PMID: 16957236 PMCID: PMC1563686 DOI: 10.1128/aem.02580-05] [Citation(s) in RCA: 171] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The antibacterial activity of photocatalytic titanium dioxide (TiO(2)) substrates is induced primarily by UV light irradiation. Recently, nitrogen- and carbon-doped TiO(2) substrates were shown to exhibit photocatalytic activities under visible-light illumination. Their antibacterial activity, however, remains to be quantified. In this study, we demonstrated that nitrogen-doped TiO(2) substrates have superior visible-light-induced bactericidal activity against Escherichia coli compared to pure TiO(2) and carbon-doped TiO(2) substrates. We also found that protein- and light-absorbing contaminants partially reduce the bactericidal activity of nitrogen-doped TiO(2) substrates due to their light-shielding effects. In the pathogen-killing experiment, a significantly higher proportion of all tested pathogens, including Shigella flexneri, Listeria monocytogenes, Vibrio parahaemolyticus, Staphylococcus aureus, Streptococcus pyogenes, and Acinetobacter baumannii, were killed by visible-light-illuminated nitrogen-doped TiO(2) substrates than by pure TiO(2) substrates. These findings suggest that nitrogen-doped TiO(2) has potential application in the development of alternative disinfectants for environmental and medical usages.
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Affiliation(s)
- Ming-Show Wong
- Department of Materials Science and Engineering, National Dong-Hwa University, Hualien, Taiwan
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Hu X, Mallikarjunan P, Koo J, Andrews LS, Jahncke ML. Comparison of kinetic models to describe high pressure and gamma irradiation used to inactivate Vibrio vulnificus and Vibrio parahaemolyticus prepared in buffer solution and in whole oysters. J Food Prot 2005; 68:292-5. [PMID: 15726971 DOI: 10.4315/0362-028x-68.2.292] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Comparisons of different models in inactivation kinetics were conducted on data obtained from high-pressure and gamma-irradiation processing. Vibrio vulnificus (MO-624) and Vibrio parahaemolyticus (O3:K6 TX-2103) suspended in phosphate-buffered saline (pH 7.4, 10(7) CFU/ml) were exposed to pressures from 207 to 379 MPa for 1 to 20 min. Inoculated whole oysters (106 CFU/g) were exposed to pressure from 276 to 379 MPa for 1 to 15 min. Pure cultures and inoculated oysters (10(6) CFU/g) also were irradiated (gamma irradiation) at doses of less than 3 kGy. Four mathematical models, the Bigelow model, Arrhenius equation, Fermi equation, and Weibull frequency distributions, were applied to microbial survival data, and performances of the different kinetic models were compared. Weibull frequency distributions can predict the high-pressure inactivation of Vibrio spp. with more accuracy in both pure cultures and inoculated oyster samples. The Fermi model provided a better description of gamma-irradiation inactivation kinetics compared with the traditional Bigelow model.
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Affiliation(s)
- Xiaopei Hu
- Biological Systems Engineering Department, Virginia Polytechnic Institute & State University, 200 Seitz Hall, Blacksburg, Virginia 24060, USA
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Jakabi M, Gelli DS, Torre JCMD, Rodas MAB, Franco BDGM, Destro MT, Landgrafi M. Inactivation by ionizing radiation of Salmonella enteritidis, Salmonella infantis, and Vibrio parahaemolyticus in oysters (Crassostrea brasiliana). J Food Prot 2003; 66:1025-9. [PMID: 12801004 DOI: 10.4315/0362-028x-66.6.1025] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Irradiation is considered one of the most efficient technological processes for the reduction of microorganisms in food. It can be used to improve the safety of food products, and to extend their shelf lives. Oysters are considered one of the most important vehicles for pathogenic bacteria because of their feeding characteristics. The aim of this study was to evaluate the influence of a gamma radiation process on high levels of Salmonella Enteritidis, Salmonella Infantis, and Vibrio parahaemolyticus incorporated by oysters (Crassostrea brasiliana), as well as the effects of the process on the survival of the oysters and on their sensory attributes. The oysters were exposed to gamma radiation (60Co) in doses ranging from 0.5 to 3.0 kGy. A dose of 3.0 kGy was generally sufficient to reduce the level of Salmonella serotypes by 5 to 6 log10 units. A dose of 1.0 kGy was sufficient to produce a 6-log10 reduction in the level of V. parahaemolyticus. The highest irradiation dose did not kill the oysters or affect their sensory attributes. Hence, a dose of 3.0 kGy can be considered effective in inactivating Salmonella and V. parahaemolyticus in oysters without changing their odor, flavor, or appearance.
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Affiliation(s)
- Miyoko Jakabi
- Departamento de Alimentos e Nutrição Experimental, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Avenida Prof. Lineu Prestes, 580, Bloco 14, 05508-900 São Paulo, Brazil
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Cui S, Jiang T, Li Y, Luo X. [Effect of irradiation on the shelf-life of aquatic products]. Wei Sheng Yan Jiu 2000; 29:120-2. [PMID: 12725095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
The effect of irradiation at doses of 0-10 kGy on the shelf-life of aquatic products was determined. The results showed that irradiation could not prolong the shelf-life of aquatic products kept at 25 degrees C. While the aquatic products were kept at refrigerator (4 degrees C), the irradiation could prolong the shelf-life and effectively reduce the total aerobic plate count. Irradiation could effectively reduce the number of coliform to less than 300/kg and eliminate Shigella shigae, Salmonella and Vibrio parahaemolyticus inoculated on shrimp, needle fish and crucian. A dose of 2.5 kGy could delay the rising of total volatile basal nitrogen in samples.
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Affiliation(s)
- S Cui
- Institute of Food Safety Control and Inspection, Ministry of Health, Beijing 100021, China
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Abstract
Vibrio parahaemolyticus differentiates from a polarly flagellated, short, rod-shaped cell known as the swimmer to the elongated, hyperflagellated, and multinucleated swarmer cell type when it is grown on a surface. The swarmer is adapted to movement over and colonization of surfaces. To understand the signal transduction mechanism by which the bacterium recognizes surfaces and reprograms gene expression, we isolated a new class of mutants defective in surface sensing. These mutants were constitutive for swarmer cell gene expression, inappropriately expressing high levels of a swarmer cell gene fusion product when grown in liquid. They showed no defect in the swimming motility system, unlike all previously isolated constitutive mutants which have defects in the alternate, polar motility system. The lesions in the majority of the newly isolated mutants were found to be in a gene, lonS, which encodes a polypeptide exhibiting 81% sequence identity to the Escherichia coli Lon protein, an ATP-dependent protease. Upstream sequences preceding the lonS coding region resemble a heat shock promoter, and the homology extends to sequences flanking lonS. The gene order appears to be clpX lonS hupB, like the organization of the E. coli locus. V. parahaemolyticus lonS complemented E. coli lon mutants to restore UV resistance and capsular polysaccharide regulation to that of the wild type. Vibrio lonS mutants were UV sensitive. In addition, when grown in liquid and examined in a light microscope, lonS mutant cells were extremely long and thus resembled swarmer cells harvested from a surface.
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Affiliation(s)
- B J Stewart
- Department of Microbiology, The University of Iowa, Iowa City 52242, USA
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Abstract
Sensitivities of the strains belonging to four vibrio biotypes to the action of furazolidone were investigated. Vibrio cholerae (classical) was most and Vibrio parahaemolyticus least sensitive to this drug. Statistical analyses revealed significant differences between any two of the four types of vibrio in respect of their sensitivity to furazolidone. The drug was radiomimetic in action, the doses of UV light (DUV) and furazolidone (Df) required for 10% survival of the vibrios being correlated by the equation, Df = 0.28 exp. (0.008 DUV). Caffeine exhibited lethal synergism with furazolidone and the synergistic effect depended on the mode of caffeine treatment, the effect being maximum when caffeine was present along with and also after furazolidone treatment. UV spectrophotometric study revealed that caffeine did not bind with native DNA but did so with denatured DNA resulting in a bathochromic shift and a quenching of the caffeine absorption maximum at 209.4 nm. The binding isotherm (Scatchard plot) indicated the presence of a heterogeneity in the binding sites and that the parameters for the strongest mode of bonding were n = 0.254 and k = 7.5 X 10(5) M-1.
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Abstract
The ultraviolet-inactivation kinetics of a number of strains of Vibrio cholerae (classical), Vibrio cholerae (el tor), NAG vibrios and Vibrio parahaemolyticus were investigated. Statistical analyses revealed significant differences between any two of the four types of vibrio in respect to their sensitivity to U.V.
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