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Theses

Caractérisation des éléments intégratifs conjugatifs de la famille ICESt3 et des facteurs influençant leur mobilité

Abstract : Integrative Conjugative Elements (ICEs) are mobile genetic elements that can be horizontally transferred from a bacterium to another, eventually regardless of the species or any other classification, allowing them to benefit from a broad host spectrum. ICEs can carry adaptive genes that can significantly improve the bacterial fitness and allow its adaptation to new ecological niches. In this work, ICEs related to ICESt3 were found in the commensal and opportunistic pathogen Streptococcus salivarius. In silico analysis highlighted the diversity of the ICESt3 family within this species, especially concerning their recombination and regulation modules, but also their adaptive genes likely available for the oral and digestive microbial community of the human host. The functionality of two ICEs found in S. salivarius was experimentally confirmed through their ability to transfer in intra- and interspecific manners. This work also allowed the identification of host factors affecting ICESt3 mobility, and revealed the importance, for the transfer and the acquisition of this ICE, of cell surface molecules such as lipoproteins, teichoic acids and exopolysaccharides. In conclusion, this thesis allowed expanding the knowledge regarding the mobile genetic elements of the ICESt3 family. This work demonstrated that these elements contribute to genome evolution of different streptococci species and gene exchanges between bacteria originated from food and the human gut flora. Finally, this study contributes to a better comprehension of the mechanisms and host factors influencing the mobility of these mobile genetic elements
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https://tel.archives-ouvertes.fr/tel-01699829
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Submitted on : Friday, February 2, 2018 - 5:16:06 PM
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Narimane Dahmane. Caractérisation des éléments intégratifs conjugatifs de la famille ICESt3 et des facteurs influençant leur mobilité. Bactériologie. Université de Lorraine, 2017. Français. ⟨NNT : 2017LORR0269⟩. ⟨tel-01699829⟩

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