Validation and analysis of modeled predictions of growth of Bacillus cereus spores in boiled rice.

The growth of psychrotrophic Bacillus cereus 404 from spores in boiled rice was examined experimentally at 15, 20, and 30 degrees C. Using the Gompertz function, observed growth was modeled, and these kinetic values were compared with kinetic values for the growth of mesophilic vegetative cells as predicted by the U.S.

Nisin in milk sensitizes Bacillus spores to heat and prevents recovery of survivors.

Decimal reduction times (D values) were determined for Bacillus cereus T spores and B. stearothermophilus ATCC 12980 spores in skim milk supplemented with various concentrations (0, 2,000, and 4,000 IU/ml) of the bacteriocin nisin by using an immersed, sealed capillary tube procedure. For both organisms, the addition of nisin lowered the apparent D values.

Thermal resistance of bacterial spores in milk-based beverages supplemented with nisin.

The effect of nisin, added in the form of Nisaplin, on the thermal resistance of bacterial spores and the effects of medium composition, exposure time, and pH on nisin enhancement of heat sensitivity were evaluated. Nisin apparently required specific nutrients to sensitize spores to heat. For example, D130 degrees C values of approximately 10 s were observed in sodium phosphate buffer with and without 6% sucrose with no significant (P> or =0.

Heat resistance of Alicyclobacillus acidoterrestris spores as affected by various pH values and organic acids.

Alicyclobacillus acidoterrestris, a thermoacidophilic sporeformer, has caused spoilage of fruit juices which had been treated with thermal processes intended to commercially sterilize the juice. The objective of this research was to document the effect of pH, acid, and temperature on the heat resistance of spores of three fruit-juice isolates of A. acidoterrestris.

Development of a streptavidin-conjugated single-chain antibody that binds Bacillus cereus spores.

Control of microorganisms such as Bacillus cereus spores is critical to ensure the safety and a long shelf life of foods. A bifunctional single chain antibody has been developed for detection and binding of B. cereus T spores.

Construction and expression of a bifunctional single-chain antibody against Bacillus cereus p6ores.

The variable-region genes of monoclonal antibody against Bacillus cereus spores were cloned from mouse hybridoma cells by reverse transcription-PCR. The heavy- and light-chain variable-region genes were connected by a 45-base linker DNA to allow folding of the fusion protein into a functional tertiary structure. For detection of protein expression, a 10-amino-acid strep tag (biotin-like peptide) was attached to the C terminus of recombinant antibody as the reporter peptide.

Cold Temperature Adaptation and Growth of Microorganisms .

Most microorganisms must accommodate a variety of changing conditions and stresses in their environment in order to survive and multiply. Because of the impact of temperature on all reactions of the cell, adaptations to fluctuations in temperature are possibly the most common. Widespread in the environment and well-equipped for cold temperature growth, psychrophilic and psychrotrophic microorganisms may yet make numerous adjustments when faced with temperatures lower than optimum.

Cold Temperature Growth of Clinical and Food Isolates of Bacillus cereus .

A collection of 27 Bacillus cereus food and clinical isolates were screened for the ability to grow at cold temperatures. Growth was examined using fluid or solid nutrient media or milk incubated at 10, 7, or 5°C. Fourteen isolates were capable of visible colony formation on brain heart infusion (BHI) agar by day 7 at 10°C; two isolates formed visible colonies by day 10 at 7°C on Trypticase soy agar.

Driving predictive modelling on a risk assessment path for enhanced food safety.

How do we best protect our citizens to allow the highest quality of life? Where do we put our food safety resources so that we gain the greatest positive impact? Risk assessment provides the critical scientific basis for these types of important risk management decisions. Increasingly, risk assessment is used to guide legislated and voluntary changes intended to improve safety, yet its formal application for enhanced food safety is in its infancy. Risk assessment includes disease characterization.

Thermal Resistance of Aeromonas hydrophila in Liquid Whole Egg .

Aeromonas hydrophila (AH) is a psychrotrophic spoilage bacterium and potential pathogen which has been isolated from a variety of refrigerated foods of animal origin, including raw milk, red meat, poultry, and commercially broken raw liquid whole egg (LWE). Decimal reduction times ( values) of 4 strains of AH (1 egg isolate, 2 egg processing plant isolates, 1 ATCC type strain) were determined in LWE using an immersed sealed capillary tube (ISCT) procedure. Initial populations (7.

Monoclonal antibodies for use in detection of Bacillus and Clostridium spores.

Five monoclonal antibodies against bacterial spores of Bacillus cereus T and Clostridium sporogenes PA3679 were developed. Two antibodies (B48 and B183) were selected for their reactivity with B. cereus T spores, two (C33 and C225) were selected for their reactivity with C.

Assessment of Risks Associated with Foodborne Pathogens: An Overview of a Council for Agricultural Science and Technology Report.

A review is presented of a report published by the Council for Agricultural Science and Technology and entitled Foodborne Pathogens: Risks and Consequences. The risk assessment approach provided the framework to define the hazard and occurrence of foodborne disease as well as the estimated economic consequences. Fifteen recommendations are detailed, including that food safety policy should be based on risk assessment, that control practices should be applied from food source to consumption, that and fundamental and applied food safety research is needed.

Acetic, lactic and citric acids and pH inhibition of Listeria monocytogenes Scott A and the effect on intracellular pH.

The effects of acetic, lactic and citric acids and pH on the growth and intracellular pH (pHin) of Listeria monocytogenes Scott A were documented and compared for total acid concentrations ranging from 50 mmol ml-1 to 250 mmol ml-1 for acetic and lactic acids and from 25 mmol ml-1 to 100 mmol ml-1 for citric acid. Initial pH values ranged from 4.7 to 6.

A proposed nonpathogenic biological indicator for thermal inactivation of Listeria monocytogenes.

Listeria innocua M1 was developed as a thermal processing indicator organism for L. monocytogenes by selection of a rifampin- and streptomycin-resistant mutant. zetaD values were 5.

Enhanced control of Listeria monocytogenes by in situ-produced pediocin during dry fermented sausage production.

To determine whether pediocin is produced and has effective antilisterial activity during food fermentation, six sausage fermentation trials were conducted with antibiotic-resistant, pediocin-producing (Bac+) Pediococcus acidilactici PAC 1.0 (Strr Rifr) and an isogenic pediocin-negative (Bac-) derivative used as a control. Meat was inoculated (ca.

Listeria innocua Transformed with an Antibiotic Resistance Plasmid as a Thermal-resistance Indicator for Listeria monocytogenes .

Listeria innocua PFEI is a chloramphenicol- and erythromycin-resistant organism obtained by electotransforming L. innocua ATCC 33091 with the plasmid pGK12. L.

Purification and some characteristics of a calcium-binding protein from Bacillus cereus spores.

A novel calcium-binding protein has been purified from the dormant spores of Bacillus cereus T. Purity of this protein was verified by SDS-PAGE and reversed-phase HPLC. Its calcium-binding ability was verified by a competitive calcium-binding assay using Chelex-100 resin and 45Ca autoradiography.

Hydrophobicity of Bacillus and Clostridium spores.

The hydrophobicities of spores and vegetative cells of several species of the genera Bacillus and Clostridium were measured by using the bacterial adherence to hexadecane assay and hydrophobic interaction chromatography. Although spore hydrophobicity varied among species and strains, the spores of each organism were more hydrophobic than the vegetative cells. The relative hydrophobicities determined by the two methods generally agreed.

Effects of heat-, CaCl2- and ethanol-treatments on activation of Bacillus spores.

The effects of heat, CaCl2, and ethanol on activation of Bacillus spores were determined by monitoring the absorbance decrease during germination in inosine. Bacillus cereus T, B. subtilis A and B.

Heat Resistance and Growth of Listeria monocytogenes in Liquid Whole Egg .

Listeria monocytogenes F5069, ATCC 19111, Scott A, and two L. monocytogenes strains isolated from egg were evaluated for growth and thermal resistance in liquid whole egg. Each strain grew in liquid whole egg at temperatures between 4 and 30°C, except Scott A which did not grow at 4 or 10°C.

Listeria monocytogenes F5069 Thermal Death Times in Liquid Whole Egg .

Thermal death times (F-values) for L. monocytogenes F5069 inoculated into sterile liquid whole egg were determined between 62 and 73°C by a submerged capillary tube procedure. The initial population was 5 × 10 to 2 × 10 CFU/tube (0.

Listeria Species in Commercially Broken Raw Liquid Whole Egg .

Commercially broken raw liquid whole egg (LWE) was obtained from 11 processing establishments across the United States on 3 or 4 occasions over an eight-month period. The samples were evaluated for the presence of Listeria species by the FDA, USDA, and cold enrichment procedures. Forty-five Listeria isolates were obtained from 15 of 42 (36%) egg samples.

Involvement of the spore coat in germination of Bacillus cereus T spores.

Bacillus cereus T spores were prepared on fortified nutrient agar, and the spore coat and outer membrane were extracted by 0.5% sodium dodecyl sulfate-100 mM dithiothreitol in 0.1 M sodium chloride (SDS-DTT) at pH 10.

Effect of Carbon Dioxide, Nitrogen and Hydrogen Gases on Germination of Clostridium botulinum Spores.

Germination of spores of Clostridium botulinum strains 62A, 213B and 12885A was monitored in modified peptone yeast extract broth flushed with CO, N, CO + H and N + H. Carbon dioxide enhanced germination of spores of each of the strains. Hydrogen gas in combination with CO or N did not substantially alter germination compared to germination in CO or N alone, even though the oxidation-reduction potential of the system was lower in the systems flushed with H.

Differing L-alanine germination requirements of hypochlorite-treated Clostridium botulinum spores from two crops.

Similar populations of hypochlorite-treated spores were enumerated from two crops of Clostridium botulinum 12885A produced by the same procedure; however, germination required different L-alanine concentrations. Lactate permitted the germination of spores from both crops with suboptimal L-alanine concentrations. The data suggest that the spores differ slightly in chemical or structural composition.