Towards a cellular factory producing biohydrocarbons: biology and biotechnology of an emerging streptophyte microalgal model

In the evolutionary history of living organisms, the gradual adaptation of certain aquatic microalgae to an aero-terrestrial way of life was a crucial period, as it gave rise to all present-day terrestrial plants. Recent sequencing of the genomes of streptophytic algae, a group little studied until now, has begun to shed light on this evolutionary process. The appearance in ancestral streptophytic algae of the ability to synthesize and excrete hydrophobic compounds such as hydrocarbons, capable of forming a water-impermeable protective layer on the cell surface, was necessarily an important step in survival and adaptation to the aerial environment. Today, the inability of industrial algae to excrete hydrocarbons is a major biotechnological barrier to the biosourced production of hydrocarbons for green chemistry and fuels. The aim of this thesis project is therefore twofold: firstly, to characterize the synthesis and excretion pathways of hydrophobic compounds in an algae that is an emerging model of streptophyte algae and the only one in which hydrocarbon synthesis enzymatic equipment similar to that found in plants is present; secondly, for applied purposes, to use genetic engineering approaches to determine a set of proteins that will maximize hydrocarbon synthesis and excretion in this model alga.