Fast screening of Bifidobacterium longum sublethal stress conditions in a novel two-stage continuous culture strategy
| Autor: | Fabrizio Arigoni, Bernard Berger, Valeria Mozzetti, Enea Rezzonico, F. Grattepanche, Christophe Lacroix |
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| Rok vydání: | 2013 |
| Předmět: |
Microbiology (medical)
Fastidious organism Microbial Viability Bifidobacterium longum food.ingredient biology Food additive Temperature Hydrogen-Ion Concentration Sodium Chloride biology.organism_classification Microbiology Stress (mechanics) Industrial Microbiology Freeze-drying food Stress Physiological Humans Fermentation Bifidobacterium Viability assay Food science Digestion |
| Zdroj: | Beneficial Microbes. 4:167-178 |
| ISSN: | 1876-2891 1876-2883 |
| Popis: | A central issue in the application of probiotics as food additives is their fastidious production and their sensitivity to many environmental stresses. The importance of inducible cell-protective mechanisms triggered by application of sublethal stresses for survival under stress conditions has been demonstrated. Continuous cultures could be a suitable and more efficient method to test stress factors on one culture instead of several repeated batch cultures. In this study, the application of a two-stage continuous culture of Bifidobacterium longum NCC2705 was investigated. The first reactor was operated under fixed conditions at 37 °C and pH 6.0 and used to produce cells with controlled physiology, mimicking cells in the late exponential growth phase. Stress pretreatment combinations of pH (6.0, 5.0 and 4.0), temperature (37, 45 and 47 °C) and NaCl (0, 5 and 10%) were tested in the second reactor. Of all tested combinations, only those of pH 4.0 significantly decreased cell viability in the second reactor compared to control conditions (37 °C, pH 6.0, 0% NaCl) and, therefore, could not be considered as sublethal stresses. Pretreatments with 5 or 10% NaCl had a negative effect on cell viability after gastric lethal stress. A significant improvement in cell resistance to heat lethal stress (56 °C, 5 min) was observed for cells pretreated at 47 °C. In contrast, heat pretreatment negatively affected cell viability after freeze drying and osmotic lethal stresses. The two-stage continuous culture allowed for efficient screening of several stress pretreatments during the same experiment with up to four different conditions tested per day. Optimal sublethal stress conditions can also be applied for producing cells with traditional batch cultures. |
| Databáze: | OpenAIRE |
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