Microalgae and active biomolecules: implementation of an innovative bioprocess for the production of human health supplements.

The pharmaceutical potential of extracts from natural products, due to their diversity of chemical structures, is being explored more and more. An example of a natural substance of major medical interest, especially in oncology, is paclitaxel, extracted from the bark of the Taxus shrub. Similarly, other plants have active substances that can be used, for example, in the treatment and improvement of cognitive functions. This project aims to develop a technological platform to assess the potential of microalgae-based bioreactors for the assisted production of molecules (or groups of molecules) of medical interest. The emphasis is on the investigation of metabolic activation processes as well as the interactions or release of active substances into the culture medium. The preferred approach involves the use of microalgae with zero or very low risk to human health, such as chlorella and species of marine origin used in aquaculture. The composition of the culture medium will be modified by the addition of compounds or plant extracts known to contain active ingredients of medical interest, specifically targeted for their effects on cognitive functions. In addition, various culture conditions will be applied in order to stimulate different metabolic pathways which could then produce, or otherwise impact or interact with the active compounds added in culture. In microalgae, it is known that the application of stress conditions (eg: nutrient deficiencies, variation in pH or temperature) induces the production of secondary metabolites as a defense or adaptation mechanism. Our hypothesis is that some of these metabolic pathways will produce or otherwise modify active molecules of medical interest in culture and we will characterize the result. In the event that these molecules are not impacted by microalgae, we hypothesize that they at the very least allow the consumption of other compounds present in the crude extracts containing the molecule of medical interest, in order to contribute to its purification and thus reduce production costs. The assay and determination of the activity of different fractions (e.g. solution of the culture medium, extracts from the biomass of microalgae) will be carried out in order to trace the main fraction of interest and to assess whether production gains and activity were obtained by our approach. These tests will be carried out in shaken flasks at the start, then the most promising conditions will be applied in bioreactors at laboratory scale (5 L) from the second year of the project. Scaling tests will be carried out in the third year of the project in larger volume bioreactors. Eventually, the continuation of this project could be considered in order to characterize more precisely the mixtures or molecular structures which are at the origin of the desired activities.