Sensitivity of Bacillus weihenstephanensis to acidic changes of the medium is not dependant on physiological state.
Food Microbiol
; 36(2): 440-6, 2013 Dec.
Article
em En
| MEDLINE
| ID: mdl-24010627
ABSTRACT
This study aims to quantify the effect of salt and acid preliminary exposure on acid resistance of vegetative cells of Bacillus weihenstephanensis. The psychrotolerant strain KBAB4 was cultured until the mid-exponentially phase (i) in BHI, (ii) in BHI supplemented with 2.5% salt or (iii) in BHI acidified at pH 5.5 with HCl. The growing cells were subsequently inactivated in lethal acid conditions ranging from 4.45 to 4.70. Based on statistical criteria, a primary mixed-Weibull model was used to fit the acid inactivation kinetics. The acid resistance was enhanced for acid-adapted cells and decreased for salt-adapted cells. The secondary modelling of the bacterial resistance allowed the quantification of the change in pH leading to a ten folds variation of the bacterial resistance, i.e. cells sensitivity (zpH). This sensitivity was not significantly affected whatever the preliminary mild exposure and the presence of sub-populations with different acid resistances. These results highlighted that pre-incubation conditions influence bacterial acid resistance without affecting the sensitivity to acidic modifications, with a 10 fold reduction of Bacillus acid resistance observed for a reduction of 0.37 pH unit. Quantification of such adaptive stress response might be instrumental in quantitative risk assessment more particularly in food formulation, particularly for low-acid minimally processed foods.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Bacillus
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Ácidos
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Meios de Cultura
Tipo de estudo:
Diagnostic_studies
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Prognostic_studies
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Risk_factors_studies
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article