La vectorisation de Propionibacterium freudenreichii CIRM-BIA 129 et de ses protéines immunomodulatrices par la matrice fromagère vers le tube digestif

Abstract : Propionibacterium freudenreichii CIRM-BIA 129 (Pf) is a beneficial bacterium used as a cheese starter. It moreover displays versatile strain-dependent probiotic properties, including the modulation of inflammation. This property results from the production of various metabolites. S-layer surface proteins (Slps), including the major SlpB protein, also play an immunomodulatory role. The "2-in-1" properties, i.e. both fermentative and probiotic properties, make Pf a suitable candidate to develop functional cheeses, in order to prevent inflammatory bowel diseases. The aim of this thesis was to study the impact of the cheese matrix on the immunomodulatory properties of Pf, mediated by its Slps proteins, compared to a culture on milk ultrafiltrate (MUF). In vitro studies suggest that the bacteria from the cheese would have a better ability to tolerate gastric and duodenal stresses, but would have less ability to survive in the colon, compared to bacteria from a MUF culture. In addition, thethe digestive proteolysis of surface proteins improves survival of Pf in the colon. In parallel, the in vitro digestion study showed that proteolysis of surface proteins was only limited by the cheese matrix. This proteolysis leads to the abolition of the anti-inflammatory effects of Slps proteins, which are not de novo expressed in the colonic environment. These results, obtained in vitro, were consistent with the in vivo study, which showed that MUF culture and cheese delivered similar amounts of metabolically active bacteria to the piglets’ colon. This in vivo study showed, however, that t
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Houem Rabah. La vectorisation de Propionibacterium freudenreichii CIRM-BIA 129 et de ses protéines immunomodulatrices par la matrice fromagère vers le tube digestif. Biochimie, Biologie Moléculaire. Agrocampus Ouest, 2019. Français. ⟨NNT : 2019NSARB320⟩. ⟨tel-02178684⟩

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