Synergistic interaction between pH and NaCl in the limits of germination and outgrowth of Clostridium sporogenes and Group I Clostridium botulinum vegetative cells and spores after heat treatment.

Group I Clostridium botulinum and Clostridium sporogenes are physiologically and genetically closely related. Both are widely distributed in the environment and can cause foodborne botulism. In this work, a physiological study was conducted with 37 isolates from spoiled canned food and five referenced strains of C.

Insights into the Structure and Protein Composition of Spores Formed at Different Temperatures.

The bacterium produces the most heat-resistant spores of any spoilage-causing microorganism known in the food industry. Previous work by our group revealed that the resistance of these spores to wet heat and biocides was lower when spores were produced at a lower temperature than the optimal temperature. Here, we used electron microcopy to characterize the ultrastructure of the coat of the spores formed at different sporulation temperatures; we found that spores produced at 55 °C mainly exhibited a lamellar inner coat tightly associated with a diffuse outer coat, while spores produced at 45 °C showed an inner and an outer coat separated by a less electron-dense zone.

Convergence of Bigelow and Arrhenius models over a wide range of heating temperatures.

The heat resistance of the bacterial spores of Moorella thermoacetica, Clostridium sporogenes, Geobacillus stearothermophilus and Bacillus coagulans was determined over a wide range of temperatures using the capillary method and thermoresistometer Mastia. The results showed that the two experimental methods gave similar heat resistance values excepted for Geobacillus stearothermophilus. The effect of temperature on thermal resistance was evaluated using the Arrhenius and Bigelow models.

Temperature impacts the sporulation capacities and spore resistance of Moorella thermoacetica.

Temperatures encountered in cannery allow growth of thermophilic spore-forming bacteria, including the strictly anaerobe Moorella thermoacetica, which grows optimally from 55 °C to 65 °C and is the main cause of spoilage of low-acid canned foods (LACFs) at high temperature. Resistance to wet-heat, biocides and UV-C of spores formed at different temperatures was assessed either for a selection of M. thermoacetica strains or for the strain M.

Spore-forming bacteria responsible for food spoilage.

This review explores the main spore-forming bacteria involved in the spoilage of various processed foods. Bakery products are specifically spoiled by Bacillus species, the dominant one being Bacillus amyloliquefaciens, while different Clostridium species classically contaminate refrigerated vacuum-packed meats. These two genera have also been isolated from milk products, even when milk is pasteurized, sterilized, dehydrated or fermented, according to heat treatment and storage temperature.

Contamination pathways of spore-forming bacteria in a vegetable cannery.

Spoilage of low-acid canned food during prolonged storage at high temperatures is caused by heat resistant thermophilic spores of strict or facultative bacteria. Here, we performed a bacterial survey over two consecutive years on the processing line of a French company manufacturing canned mixed green peas and carrots. In total, 341 samples were collected, including raw vegetables, green peas and carrots at different steps of processing, cover brine, and process environment samples.

Genotypic and phenotypic characterization of foodborne Geobacillus stearothermophilus.

Geobacillus stearothermophilus is the main thermophilic spore former involved in flat sour spoilage of canned foods. Three typing methods were tested and applied to differentiate strains at intra-species level: panC sequence analysis, REP-PCR and M13-PCR. panC gene was highly conserved within the studied strains, suggesting a low intra-specific diversity.

A new chemically defined medium for the growth and sporulation of Bacillus cereus strains in anaerobiosis.

A new chemically defined liquid medium, MODS, was developed for the aerobic growth and anaerobic growth and sporulation of Bacillus cereus strains. The comparison of sporulation capacity of 18 strains of B. cereus has shown effective growth and spore production in anaerobiosis.

Absence of oxygen affects the capacity to sporulate and the spore properties of Bacillus cereus.

This study was performed to evaluate the effect of anaerobiosis on the formation of Bacillus cereus spores and their resulting properties. For this purpose, an appropriate sporulation medium was developed (MODs). Sporulation of 18 strains from different phylogenetic groups of B.

Spores of Bacillus cereus strain KBAB4 produced at 10 °C and 30 °C display variations in their properties.

Spores of the psychrotrophic Bacillus cereus KBAB4 strain were produced at 10 °C and 30 °C in fermentors. Spores produced at 30 °C were more resistant to wet heat at 85 °C, 1% glutaraldehyde, 5% hydrogen peroxide, 1M NaOH and pulsed light at fluences between 0.5 and 1.

Comparative subproteome analyses of planktonic and sessile Staphylococcus xylosus C2a: new insight in cell physiology of a coagulase-negative Staphylococcus in biofilm.

Staphylococcus xylosus is a Gram-positive bacterium found on the skin of mammals and frequently isolated from food plants and fermented cheese or meat. To gain further insight in protein determinants involved in biofilm formation by this coagulase-negative Staphylococcus, a comparative proteomic analysis between planktonic and sessile cells was performed. With the use of a protocol previously developed, protein patterns of the cytoplasmic and cell envelope fractions were compared by 2-DE.

Proteomic analysis of cell envelope from Staphylococcus xylosus C2a, a coagulase-negative staphylococcus.

Staphylococcus xylosus is a saprophytic bacterium commonly found on skin of mammals but also used for its organoleptic properties in manufacturing of fermented meat products. This bacterium is able to form biofilms and to colonize biotic or abiotic surfaces, processes which are mediated, to a certain extent, by cell-envelope proteins. Thus, the present investigation aimed at evaluating and adapting different existing methods for cell-envelope subproteome analyses of the strain S.