Valorization of CO2-rich yeast exhaust streams viamicroalgal cultivation: sustainable mixed cellularbiomass as precursors for aviation and marine biofuels

This work presents an integrated bioprocessing approach for the valorization of CO₂-rich exhaust streams generated during oleaginous yeast cultivation through their utilization in microalgal production. Heterotrophic cultivation of Trichosporon oleaginosus was coupled with autotrophic cultivation of Tetradesmus obliquus, enabling the reuse of fermentation-derived CO₂ while simultaneously producing yeast and microalgal biomass as sustainable precursors for advanced biofuels.

Two experimental configurations were evaluated, progressing from a proof-of-concept system to a process-representative setup integrating continuous two-stage yeast cultivation with semi-continuous microalgal production. The integrated systems demonstrated the feasibility of CO₂ transfer and utilization between the two cultivation processes, achieving approximately 16% CO₂ capture efficiency. The results provide valuable data for further process optimization and scale-up toward integrated biorefineries combining biological carbon utilization with solar-driven hydrothermal liquefaction (HTL) for the production of sustainable aviation and marine biofuels.