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Réseaux de communication au sein de communautés microbiennes environnementales

Abstract : Quorum sensing systems (QSSs) are genetic systems supporting cell-cell or bacteriophage-bacteriophage communication via the production and the detection of a signal molecule, the extracellular concentration of which reflects the density of the QSS-encoding population. QSSs have a prime importance in the regulation of key biological processes such as virulence, sporulation or biofilm formation in bacteria, conjugation in plasmids or lysogeny in temperate bacteriophages. However, the genetic diversity of QSSs remains largely underexplored and the same holds for the diversity of organisms, plasmids and viruses encoding these systems. Hence, many bacterial and viral density-dependent behaviors likely await to be discovered, some of which could perhaps transform our views of microbial adaptation and of the co-evolution between bacteria and their mobile genetic elements. Specifically, this PhD in evolutionary bioinformatics explores the phylogenetic and functional diversity of quorum sensing using genome and network analysis methods applied to genetic elements traditionally neglected by this research field: genomes of poorly known lineages such as CPRs and DPANNs, environmental metagenomes, viral genomes or plasmids. In particular, this thesis lays the theoretical foundations for the inference of communication networks within environmental microbial communities and includes the development of a new method allowing the identification of QSSs of the RRNPP type (Rap-Rgg-NprR-PlcR-PrgX) that are non-homologous to already known QSSs. This work notably reveals the first bilingual bacteriophages, i.e. encoding two QSSs belonging to different genetic families, as well as the first bacteriophages predicted to manipulate in a density-dependent manner the biology of their bacterial host.
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Submitted on : Wednesday, June 29, 2022 - 4:08:38 PM
Last modification on : Tuesday, August 2, 2022 - 4:04:27 AM

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  • HAL Id : tel-03709098, version 1

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Charles Bernard. Réseaux de communication au sein de communautés microbiennes environnementales. Interactions entre organismes. Sorbonne Université, 2022. Français. ⟨NNT : 2022SORUS010⟩. ⟨tel-03709098⟩

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