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Vers la reprogrammation métabolique de la cyanobactérie modèle Synechocystis pour la production durable de biocarburants : structuration des flux du carbone par CP12 et implications sur l’équilibre bioénergétique, l’hydrogénase et l’intégrité génomique

Abstract : Biotechnology is a powerful tool allowing exploitation of biological circuits to produce compounds with multiple uses (medicine, nutrition, industrial…). Cyanobacteria have valuable genetic and trophic properties which could reduce the costs and the environmental footprint of these processes (photosynthesis, CO₂ fixation, assimilation of diverse nitrogen sources…). They also naturally produce energetic molecules such as H₂ from which new and sustainable biofuels sectors may rise. However, a global and fine understanding of their physiology is required in order to design an efficient biological chassis with these organisms. They are genetically manipulable but also exhibit a strong versatility favoring fixation of mutations that can be either beneficial or harmful to their large-scale cultivation. Over the course of my PhD, I constructed and studied mutants of a CO₂ fixation regulator whose activation is linked to photosynthesis. I showed that the Calvin cycle activity synchronizes carbon fluxes and redox status in Synechocystis and that its deregulation affects the metabolism in a pleiotropic manner. I was specifically interested into the carbon/nitrogen balance in this species and its urea metabolism which is of prime interest in biotechnology. I demonstrated that the latter was in competition with the hydrogenase for the insertion of nickel into their respective catalytic centers. Scarcity of this metal leads to selection of mutants thriving upon prolonged exposure to urea that retained a high capacity of H₂ production in presence of this nitrogenic substrate. This work shows that the metabolism of Synechocystis can be altered in favor of other cellular processes. Omics approaches allow global identification of the physiological responses induced as well as the biological compensation mechanisms. These observations are discussed with regards to biotechnological implications of genetic instability and the need to strengthen our understanding of metabolic and genetic plasticity in cyanobacteria.
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https://tel.archives-ouvertes.fr/tel-01791091
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Submitted on : Monday, July 23, 2018 - 2:03:09 PM
Last modification on : Wednesday, October 14, 2020 - 4:05:18 AM
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  • HAL Id : tel-01791091, version 2

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Théo Veaudor. Vers la reprogrammation métabolique de la cyanobactérie modèle Synechocystis pour la production durable de biocarburants : structuration des flux du carbone par CP12 et implications sur l’équilibre bioénergétique, l’hydrogénase et l’intégrité génomique. Biologie moléculaire. Université Paris-Saclay, 2017. Français. ⟨NNT : 2017SACLS257⟩. ⟨tel-01791091v2⟩

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