Bioscience and Biotechnology Institute of Aix-Marseille
Energies | Renewable energies | Bioenergy | Biofuel | Biohydrogen | Microalgae | Photosynthesis
Microalgae are able to synthesize fatty acids and accumulate them in the form of oil reserves (up to 50% of their dry weight). Fatty acids (or derivatives) extracted from algal biomass have important potential applications in biofuels (biodiesel, biopetroleum), human nutrition (omega-3 polyunsaturated fatty acids) and green chemistry (building blocks for biopolymers, lubricants, etc.). However, major biological barriers still need to be overcome to ensure the profitability of the sector. Indeed, the accumulation of oil in microalgae occurs only stress conditions (e.g. nutrient deficiency), which limits cell growth and thus the productivity of biomass and oil. In addition, biofuels and human nutrition applications require improved "quality" of microalgae oil, that is to say, optimization of the fatty acid composition for each application.
The research project aims at understanding the biosynthesis of storage lipids (triacylglycerols) and its regulations in relation to environmental conditions (light, nitrogen deficiency, etc.) and energy capture reactions (photosynthesis). They are conducted mainly in the microalgae Chlamydomonas reinhardtii model. The work is based on a formal genetic approach to isolate mutants affected in their ability to accumulate or mobilize oil in various culture conditions (including condition for optimal growth) and mutants with a modified fatty acids profile. Screening of the mutants is carried out by high-throughput methods (flow cytometer, GC-MS with automated sample preparation). After identification of genes of interest and fine characterization of isolated mutants by lipidomics analysis (LC-MS/MS), innovative strategies to improve oil content and quality are proposed.
Alkanes and linear alkenes are important components of fossil fuels. Their synthesis by microalgae (from membrane or storage fatty acids) and excretion into the culture medium, would overcome the costly steps of biomass harvesting, oil extraction and conversion biodiesel. Research conducted in the laboratory aims at identifying in various microalgae (model species or species of industrial interest) the metabolic pathways responsible for the synthesis of alkanes and alkenes from fatty acids.
A last laboratory research topic concerns the functionalization of fatty acids for use in Green Chemistry. The work aims to identify in microalgae or plants new enzymes for introducing functional groups (hydroxy, epoxy, etc.) to particular positions of the carbon chain of fatty acids.
CEA is a French government-funded technological research organisation in four main areas: low-carbon energies, defense and security, information technologies and health technologies. A prominent player in the European Research Area, it is involved in setting up collaborative projects with many partners around the world.