title: Listeria monocytogenes dairy isolates show a different proteome response to sequential exposure to gastric and intestinal fluids.
abstract: The gastrointestinal system poses different stresses to the foodborne pathogen, Listeria monocytogenes, including the low pH of the stomach and the presence of bile and the high osmolality of the intestinal fluid. The present study evaluated how previous exposure of three L. monocytogenes dairy isolates (C882 and T8, serovar 4b isolates and A9 serovar 1/2a or 3b isolate) to a cheese-simulated medium (p H5.5 and 3.5% NaCl [w/v], adapted cultures) affected subsequent survival in a simulated gastrointestinal system. Listerial cultures exposed to the cheese-simulated medium at pH7.0, with no added NaCl, were considered non-adapted. To investigate the main events involved in listerial survival during the gastric and intestinal subsequent challenge, a proteomic approach was used. All L. monocytogenes strains were able to survive the deleterious effects of the gastrointestinal fluids and no significant differences were observed between adapted and non-adapted cells. However the L. monocytogenes strains showed a different protein pattern in response to the gastrointestinal stress. Data indicated that synthesis of stress related proteins is more pronounced in non-adapted cells. Although, a significant number of enzymes involved in glycolysis and energy production were also consistently over-produced by the three strains. These findings provided new insights into the means used by L. monocytogenes to overcome the gastrointestinal system and allow the pathogen to move to the next phase of the infectious process.
authors.affiliation: Universidade do Algarve - FCT, IBB-CBME, Campus de Gambelas, 8005-139, Faro, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Melo
authors.forename: D
authors.initials: D
authors.lastname: Schrama
authors.forename: S
authors.initials: S
authors.lastname: Hussey
authors.forename: P W
authors.initials: PW
authors.lastname: Andrew
authors.forename: M L
authors.initials: ML
authors.lastname: Faleiro
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D002611:Cheese / Q000382:microbiology; D041981:Gastrointestinal Tract / Q000737:chemistry*; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D050296:Microbial Viability; D020543:Proteome / Q000187:drug effects / Q000235:genetics*; D040901:Proteomics; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; D020543:Proteome; D012965:Sodium Chloride