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BIP CNRS

Engineer / July 2026 to June 2027

Carbon‑concentrating mechanisms in photosynthetic microorganisms

Ribulose‑1,5‑bisphosphate carboxylase/oxygenase (RuBisCO), the key enzyme of the Calvin–Benson–Bassham cycle, is ubiquitous across photosynthetic organisms and underpins virtually all primary production on Earth. Despite this central role, RuBisCO is characterised by a low catalytic turnover and limited substrate specificity. Photosynthetic microorganisms overcome these constraints by compartmentalising RuBisCO within specialised, membrane‑less condensates — pyrenoids in algae and carboxysomes in cyanobacteria — which form the core of carbon‑concentrating mechanisms (CCMs).

These condensates differ in composition and likely in physicochemical behaviour. This PhD project aims to dissect their molecular organisation and to determine how RuBisCO condensation influences its catalytic performance. Using in vitro reconstitution approaches, the project will quantify key physicochemical parameters such as substrate and product diffusion, local pH, and CO₂/O₂ partitioning.