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Theses

Maitrise des risques de contamination des produits alimentaires tunisiens par le groupe Bacillus cereus

Abstract : This thesis focused on evaluating the level of risk represented by Bacillus cereus group bacteria in Tunisian food and testing the effectiveness of their control by treating industrial surfaces with bacteriophages. A collection of 191 isolates was created from 687 food matrices. Nearly 40% of the isolates were found to belong to the group, with high genetic diversity (143 PFGE profiles and 99 ERIC-PCR profiles) and an intermediate thermal profile (signatures 16S rDNA-1 m and-2 p). Nearly 60% of the group's isolates belong to the phylogenetic group III, which is potentially pathogenic. Spores have a higher rate of adhesion than vegetative cells. Twelve toxigenic groups have been identified.At least one of the genes of each of the NHE and HBL complexes are present, whether or not associated with bceT, cytK 2 and these. After 18 hours of incubation at 30°C, nearly 71% of the isolates are cytotoxic. Different combinations of virulence factors are associated with cytotoxic potential and a clear link appears between cytotoxicity and food type. The collection has been shown to be sensitive to many antibiotics, while it is resistant to ampicillin and novobiocin. Of the 7 bacteriophages selected, 5 have a unique protein profile while all have similar genome size and restriction profiles. They are used to prevent the formation of biofilms and to treat them. This work confirms the health risk associated with the presence of the B. cereus group in Tunisian foods and the promising role of bacteriophages as biocontrol tools.
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Submitted on : Tuesday, September 8, 2020 - 10:32:02 AM
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  • HAL Id : tel-02933085, version 1
  • PRODINRA : 488074

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Maroua Gdoura Épouse Ben Amor. Maitrise des risques de contamination des produits alimentaires tunisiens par le groupe Bacillus cereus. Biochimie, Biologie Moléculaire. Agrocampus Ouest; Université de Sfax. Faculté des sciences, 2019. Français. ⟨NNT : 2019NSARB324⟩. ⟨tel-02933085⟩

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