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Author (up) Aertsen, A.; Michiels, C.W. file  url
openurl 
  Title SulA-dependent hypersensitivity to high pressure and hyperfilamentation after high-pressure treatment of Escherichia coli lon mutants Type Journal Article
  Year 2005 Publication Research in Microbiology Abbreviated Journal Res Microbiol  
  Volume 156 Issue 2 Pages 233-237  
  Keywords Colony Count, Microbial; Culture Media; Escherichia coli--genetics, growth & development; Escherichia coli Proteins--genetics, metabolism; Gene Expression Regulation, Bacterial; Hydrostatic Pressure; Mutation; Protease La--genetics; SOS Response (Genetics); Ultraviolet Rays  
  Abstract High-pressure treatment (>100 MPa) is known to induce several heat shock proteins as well as an SOS response in Escherichia coli. In the current work, we have investigated properties with respect to high-pressure treatment of mutants-deficient in Lon, a pressure-induced ATP-dependent protease that belongs to the heat shock regulon but that also has a link to the SOS regulon. We report that lon mutants show increased pressure sensitivity and exhibit hyperfilamentation during growth after high-pressure treatment. Both phenotypes could be entirely attributed to the action of the SOS protein SulA, a potent inhibitor of the cell division ring protein FtsZ and a specific target of the Lon protease, since they were suppressed by knock-out of SulA. Introduction of the lexA1 allele, which effectively blocks the entire SOS response, also suppressed the high pressure hypersensitivity of lon mutants, but not their UV hypersensitivity. These results indicate the existence of a SulA-dependent pathway of high-pressure-induced cell filamentation, and suggest involvement of the SOS response, and particularly of SulA, in high-pressure-mediated cell death in E. coli strains which are compromised in Lon function.  
  Call Number Serial 301  
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Author (up) Girennavar, B.; Cepeda, M.L.; Soni, K.A.; Vikram, A.; Jesudhasan, P.; Jayaprakasha, G.K.; Pillai, S.D.; Patil, B.S. file  url
openurl 
  Title Grapefruit juice and its furocoumarins inhibits autoinducer signaling and biofilm formation in bacteria Type Journal Article
  Year 2008 Publication International Journal of Food Microbiology Abbreviated Journal Int J Food Microbiol  
  Volume 125 Issue 2 Pages 204-208  
  Keywords Analysis of Variance; Beverages; Biofilms/*growth & development; Biomass; Citrus paradisi; Colony Count, Microbial; Escherichia coli O157/drug effects/physiology; Food Contamination/*prevention & control; Food Microbiology; Furocoumarins/isolation & purification/*pharmacology; Gram-Negative Bacteria/drug effects/*physiology; Gram-Positive Bacteria/drug effects/*physiology; Pseudomonas aeruginosa/drug effects/physiology; Quorum Sensing; Salmonella typhimurium/drug effects/physiology; Signal Transduction  
  Abstract Cell-to-cell communications in bacteria mediated by small diffusible molecules termed as autoinducers (AI) are known to influence gene expression and pathogenicity. Oligopeptides and N-acylhomoserine lactones (AHL) are major AI molecules involved in intra-specific communication in gram-positive and gram-negative bacteria respectively, whereas boronated-diester molecules (AI-2) are involved in inter-specific communication among both gram-positive and gram-negative bacteria. Naturally occurring furocoumarins from grapefruit showed >95% inhibition of AI-1 and AI-2 activities based on the Vibrio harveyi based autoinducer bioassay. Grapefruit juice and furocoumarins also inhibited biofilm formation by Escherichia coli O157:H7, Salmonella typhimurium and Pseudomonas aeruginosa. These results suggest that grape fruit juice and furocoumarins could serve as a source to develop bacterial intervention strategies targeting microbial cell signaling processes.  
  Call Number Serial 1579  
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Author (up) Pothakos, V.; Snauwaert, C.; De Vos, P.; Huys, G.; Devlieghere, F. file  url
openurl 
  Title Monitoring psychrotrophic lactic acid bacteria contamination in a ready-to-eat vegetable salad production environment Type Journal Article
  Year 2014 Publication International Journal of Food Microbiology Abbreviated Journal Int J Food Microbiol  
  Volume 185 Issue Pages 7-16  
  Keywords Biodiversity; Capsicum/microbiology; Colony Count, Microbial; DNA Fingerprinting; Food Industry/*methods/standards; *Food Microbiology; Genes, Bacterial/genetics; Leuconostoc/genetics/*isolation & purification; Vegetables/*microbiology; Leuconostoc gelidum subsp. gasicomitatum; Psychrotrophic LAB; Source tracking; Spoilage; Vegetable salads  
  Abstract A study monitoring lactic acid bacteria contamination was conducted in a company producing fresh, minimally processed, packaged and ready-to-eat (RTE) vegetable salads (stored at 4 degrees C) in order to investigate the reason for high psychrotrophic LAB levels in the products at the end of shelf-life. Initially, high microbial counts exceeding the established psychrotrophic thresholds (>10(7)-10(8)CFU/g) and spoilage manifestations before the end of the shelf-life (7days) occurred in products containing an assortment of sliced and diced vegetables, but within a one year period these spoilage defects became prevalent in the entire processing plant. Environmental sampling and microbiological analyses of the raw materials and final products throughout the manufacturing process highlighted the presence of high numbers of Leuconostoc spp. in halved and unseeded, fresh sweet bell peppers provided by the supplier. A combination of two DNA fingerprinting techniques facilitated the assessment of the species diversity of LAB present in the processing environment along with the critical point of their introduction in the production facility. Probably through air mediation and surface adhesion, mainly members of the strictly psychrotrophic species Leuconostoc gelidum subsp. gasicomitatum and L. gelidum subsp. gelidum were responsible for the cross-contamination of every vegetable handled within the plant.  
  Call Number Serial 1670  
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Author (up) Sengun, I.Y.; Karapinar, M. file  url
openurl 
  Title Effectiveness of lemon juice, vinegar and their mixture in the elimination of Salmonella typhimurium on carrots (Daucus carota L.) Type Journal Article
  Year 2004 Publication International Journal of Food Microbiology Abbreviated Journal Int J Food Microbiol  
  Volume 96 Issue 3 Pages 301-305  
  Keywords Acetic Acid/*pharmacology; Citrus/*chemistry; Colony Count, Microbial; Consumer Product Safety; Daucus carota/*microbiology; Disinfectants/*pharmacology; Food Contamination/prevention & control; Food Microbiology; Plant Extracts/*pharmacology; Salmonella typhimurium/*drug effects/growth & development; Time Factors  
  Abstract Lemon juice, vinegar and the mixture of lemon juice and vinegar (1:1) were tested for their effectiveness in reducing the counts of inoculated Salmonella typhimurium (approximately 6 and 3 log cfu/g) on carrots. Treatment of carrot samples with lemon juice vinegar alone for different exposure times (0, 15, 30 and 60 min) caused significant reductions ranging between 0.79-3.95 and 1.57-3.58 log cfu/g, respectively, while the number of pathogens was reduced to an undetectable level after 30-min treatment by combined used lemon juice vinegar.  
  Call Number Serial 1724  
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Author (up) Somolinos, M.; Garcia, D.; Manas, P.; Condon, S.; Pagan, R. file  url
doi  openurl
  Title Effect of environmental factors and cell physiological state on Pulsed Electric Fields resistance and repair capacity of various strains of Escherichia coli Type Journal Article
  Year 2008 Publication International Journal of Food Microbiology Abbreviated Journal Int J Food Microbiol  
  Volume 124 Issue 3 Pages 260-267  
  Keywords Colony Count, Microbial; Electromagnetic Fields/*adverse effects; Escherichia coli/*growth & development/*physiology; Escherichia coli O157/growth & development/physiology; *Food Microbiology; Food Preservation/*methods; Humans; Hydrogen-Ion Concentration; Kinetics; Temperature; Time Factors  
  Abstract The aim was to determine the resistance variation of four strains of Escherichia coli to Pulsed Electric Fields (PEF), the role of the sigma factor RpoS in PEF resistance, as well as the influence of several environmental factors and the cell physiological state on the PEF resistance and repair capacity. The rpoS null mutant, E. coli BJ4L1, exhibited decreased PEF resistance as compared with its wild-type parent, BJ4. W3110 and O157:H7 were the most PEF-resistant strains: whereas 2 and more than 3 Log10 cycles of BJ4 and BJ4L1 cells, respectively, were inactivated after 50 pulses at 35 kV/cm, only 0.5 Log10 cycle of inactivation of W3110 and O157:H7 was attained. A different pattern was observed and the resistance variation among strains was largely reduced, when selective recovery media were used. At exponential growth phase, the resistance of the four strains was lower, and more than 4 Log10 cycles of inactivation of all strains tested were attained at 30 kV/cm. Previous heat and cold shock treatments scarcely influenced cell PEF resistance. PEF survival increased with the reduction in water activity of the treatment medium to 0.94: the occurrence of sublethally injured cells was negligible, and less than 1 Log10 cycle of inactivation was attained at 35 kV/cm. PEF-treated cells were sensitive to a subsequent storage at pH 4.0 or in the presence of sorbic acid, attaining a final inactivation of 4-5 Log10 cycles after 24 hour-incubation. In conclusion, the work confirms the role of rpoS in PEF resistance. E. coli strains exhibit large differences in PEF resistance. These differences were less important when cells were recovered under selective conditions. Both resistance variation among strains and occurrence of sublethal damage were noticeably influenced by the environmental factors tested.  
  Call Number Serial 314  
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