Screening for Bacillus subtilis mutants deficient in pressure induced spore germination: identification of ykvU as a novel germination gene.

Exposure to high pressure induces germination in spores of Bacillus subtilis. To investigate the mechanisms of this process and to compare the pressure and nutrient induced germination pathways, a random transposon knock-out library of B. subtilis was constructed and screened for clones with a compromised pressure induced germination at 100 MPa.

Inactivation of Escherichia coli by high hydrostatic pressure at different temperatures in buffer and carrot juice.

The inactivation of Escherichia coli MG1655 was studied at 256 different pressure (150-600 MPa)-temperature (5-45 degrees C) combinations under isobaric and isothermal conditions in Hepes-KOH buffer (10 mM, pH 7.0) and in fresh carrot juice. A linear relationship was found between the log10 of inactivation and holding time for all pressure-temperature combinations in carrot juice, with R2-values>or=0.

Inactivation of Bacillus cereus spores in milk by mild pressure and heat treatments.

The objective of this work was to study the germination and subsequent inactivation of Bacillus cereus spores in milk by mild hydrostatic pressure treatment. In an introductory experiment with strain LMG6910 treated at 40 degrees C for 30 min at 0, 100, 300 and 600 MPa, germination levels were 1.5 to 3 logs higher in milk than in 100 mM potassium phosphate buffer (pH 6.

High sucrose concentration protects E. coli against high pressure inactivation but not against high pressure sensitization to the lactoperoxidase system.

The inactivation of Escherichia coli by high hydrostatic pressure treatment at up to 550 MPa and 20 degrees C was studied in potassium phosphate buffer containing high concentrations of sucrose. E. coli strain MG1655 was pressure-sensitive in the absence of sucrose, but became highly pressure resistant in the presence of 10% to 50% (w/v) sucrose.

The lactoperoxidase system increases efficacy of high-pressure inactivation of foodborne bacteria.

The inactivation of eight different bacteria comprising Escherichia coli LMM1010 and MG1655, respectively a pressure-resistant strain and the corresponding wild-type, Salmonella Typhimurium, Pseudomonas fluorescens, Staphylococcus aureus, Enterococcus faecalis, Listeria innocua and Lactobacillus plantarum, by high hydrostatic pressure in skim milk supplemented with the lactoperoxidase-hydrogen peroxide-thiocyanate (LP) system at naturally occurring concentration was studied. In the absence of pressure treatment, the LP system had either no effect, i.e.