Dissecting Lipid Metabolism in the Green Microalga Chlamydomonas reinhardtii using Genetic and Lipidomic Approaches
Caroline Cagnon, Audrey Beyly-Adriano, Séverine Bouvet, Bertrand Légeret, Fred Beisson, Gilles Peltier, Yonghua Li-Beisson
CEA/CNRS/Aix-Marseille Université
CEA Cadarache France

Organic carbons fixed by photosynthetic organisms provide rich sources for food, feed and chemical industries. Fatty acids and its derivatives are particularly sought-after molecules because they are not only precursors to biodiesel, but also provide the basis for a range of green chemical applications. Microalgae species with superior lipid productivity are highly desirable. To achieve a profitable oil production from microalgae, identification of factors governing lipid synthesis and turnover is desirable. The green microalga Chlamydomonas reinhardtii is amenable to genetic analyses and has recently emerged as a model to study lipid metabolism. Here we present our effort toward isolation and characterization of mutants affected in lipid metabolism based on a combination of flow cytometry, microscopy, and lipidomic approaches (GC-MS, HPTLC and LC-MS/MS). Over 80 insertional mutants were isolated by screening 4000 transformants cultivated under 3 conditions (nitrogen-replete i.e. optimal growth, nitrogen-depleted and reserve remobilization). Most of the mutants were found to be affected in oil remobilization, which points toward a likely important role of lipid turnover processes in the level of oil that can be accumulated in Chlamydomonas cells. A first subset of mutants was selected for further analyses. Flanking region of cassette insertions were identified using PCR-based techniques. In parallel, to gain more insights into the changes occurring in the mutants and guide future complementation studies, the profile of storage and membrane lipid molecular species was analyzed by LC-MS/MS.