title: Combined effect of anaerobiosis, low pH and cold temperatures on the growth capacities of psychrotrophic Bacillus cereus.
abstract: Psychrotrophic strains of the foodborne pathogen Bacillus cereus can multiply during the refrigerated storage of food products. The aim of this study was to determine the impact of anaerobiosis on the growth of two psychrotrophic B. cereus strains exposed to acidic pH at a cold temperature in a laboratory medium. At 10 °C, growth occurred at pH values equal to or higher than 5.7 during anaerobiosis, whereas aerobic growth was observed from pH 5.4. Growth rates during aerobiosis were similar at pH 5.4 and pH 7. No growth was observed for the two tested strains at 8 °C without oxygen regardless of the pH; however, both strains grew at this temperature from pH 5.4 in the presence of oxygen. These pH growth limits in aerobiosis are consistent with those reported for different strains and different foods or media, but no other studies have described anaerobic growth at acidic pH values. The maximal B. cereus concentration was approximately 6.0 log10 CFU/ml for cultures in the absence of oxygen and approximately 8.0 log10 CFU/ml for cultures in the presence of oxygen. In conclusion, we found that the combination of anaerobiosis, pH < 5.7 at 10 °C, or anaerobiosis and temperatures ≤8 °C prevent psychrotrophic B. cereus growth.
authors.affiliation: UMR408 SQPOV « Sécurité et Qualité des Produits d'Origine Végétale », INRA, University of Avignon, 84000 Avignon, France.
authors.forename: Alizée
authors.initials: A
authors.lastname: Guérin
authors.affiliation: UMR408 SQPOV « Sécurité et Qualité des Produits d'Origine Végétale », INRA, University of Avignon, 84000 Avignon, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Dargaignaratz
authors.affiliation: UMR408 SQPOV « Sécurité et Qualité des Produits d'Origine Végétale », INRA, University of Avignon, 84000 Avignon, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Broussolle
authors.affiliation: UMR408 SQPOV « Sécurité et Qualité des Produits d'Origine Végétale », INRA, University of Avignon, 84000 Avignon, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Clavel
authors.affiliation: UMR408 SQPOV « Sécurité et Qualité des Produits d'Origine Végétale », INRA, University of Avignon, 84000 Avignon, France. Electronic address: Christophe.nguyen-the@avignon.inra.fr.
authors.forename: Christophe
authors.initials: C
authors.lastname: Nguyen-The
mesh_terms: D000693:Anaerobiosis; D001409:Bacillus cereus / Q000254:growth & development* / Q000378:metabolism; D003080:Cold Temperature; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D013171:Spores, Bacterial / Q000254:growth & development; D014618:Vacuum
keywords: Acid; Growth limits; Low temperature; Oxygen