Optimisation of Brassica rapa rapa (turnip) hairy root culture media for the production of biomass and secretion of recalcitrant recombinant proteins

The increasing demand for recombinant proteins used as therapeutic agents has influenced the development of different production platforms. Plant systems are attractive for recombinant protein production as they offer safety (no risk of human-threatening viral contamination), low upstream costs, complex glycosylation, and high scalability. Among the plant-based systems, hairy root cultures present several advantages such as rapid propagation, genotypic and phenotypic stability, and among others, possible extracellular secretion of expressed proteins in a well-defined medium. The optimization of the hairy root cultures to produce sufficient yields of secreted and easy-to-purify recombinant proteins is an on-going endeavor as it usually depends on the protein of interest. As part of the H2020 PharmaFactory project, several strategies are being assessed to maximize the productivity of “hard-to-produce” recombinant proteins in hairy root cultures. In this regard, we are evaluating the impact of selected culture medium agents on productivity. The aim is to identify, from a range of culture medium additives, those that when used in combination or alone, increase the productivity of recalcitrant recombinant proteins. The potential of such agents has been evaluated based on statistical experimental design. Subsequently, with the biomass values and recombinant protein yields retrieved, a model is created to predict culture media conditions giving rise to the best recombinant protein yield. Currently, sucrose and calcium chloride have demonstrated to be important for the biomass production. More research is still required in order to create models with a higher prediction power.