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Theses

Les adaptations bactériennes améliorent la survie de Propionibacterium freudenreichii durant le séchage et le stockage

Abstract : Probiotic and starters are produced in powder form to facilitate storage, and usage. These beneficial bacteria are usually dried by freeze-drying, which is expensive with low productivity. Therefore, spray drying is an alternative and sustainable process to produce beneficial bacteria. Unfortunately, spray drying imposes osmotic, heat and oxidative stresses, this process can thus lead to the death of an important bacterial death.In this work, Propionibacterium freudenreichii adaptation to different treatments were studied to better understand their impact on cross-protections. Adaptation mechanisms included compatible solutes accumulation, general stress protein over-production and modulation of membrane fatty acids composition. During osmoadaptation, compatible solutes accumulation was fine-tuned by the medium composition and especially by the amount of non-protein nitrogen sources and of carbohydrates.Accumulation of high amounts of glycine betaine during osmoadaptation, led to high survival during freeze-drying. By contrast, accumulation of high amounts of glycine betaine and trehalose, led to high viability during spray drying. Different adaptations can trigger the same adaptation mechanisms. Accumulation of high amounts of trehalose and of glycine betaine was triggered by the addition of saccharides, combine to osmoadaptation or to heat-adaptation. Adaptation can be optimized to confer bacteria enhanced resistance during drying processes, storage and digestion. This work opens new avenues for the production of starters and probiotics with enhanced robustness.
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Submitted on : Tuesday, February 16, 2021 - 10:07:20 AM
Last modification on : Wednesday, February 17, 2021 - 3:32:53 AM

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  • HAL Id : tel-02788649, version 2
  • PRODINRA : 492990

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Floriane Gaucher. Les adaptations bactériennes améliorent la survie de Propionibacterium freudenreichii durant le séchage et le stockage. Sciences agricoles. Agrocampus Ouest, 2019. Français. ⟨NNT : 2019NSARB329⟩. ⟨tel-02788649v2⟩

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