Microalgae are single-celled photosynthetic organisms that grow on atmospheric carbon dioxide, sunlight, and dissolved mineral nutrients. Under the proper conditions, microalgae also produce fatty acids stored as lipids, which can be readily converted to biofuel such as biodiesel. This proposed research will explore a new process called selective fermentation to address two major roadblocks facing the continued commercial development algal biofuel production processes: safe and efficient extraction of the lipids, and beneficial use of the non-lipid biomass. Selective fermentation involves the conversion of carbohydrate and protein fractions of microalgae biomass to short-chain fatty acids while leaving the lipid fraction intact and more easily available for extraction by non-toxic solvents. This research has the potential to improve biofuel yield from algal biomass and reduce waste, thereby increasing efficiency and promoting sustainability of algal biofuel production processes.

The production of liquid transportation fuels from microalgae faces many challenges, including the safe and efficient extraction of lipids, and in the beneficial use of the non-lipid components in the biomass. This project will study the potential of selective fermentation to simultaneously address these two challenges. In the proposed selective fermentation process, the carbohydrate and protein fractions of the microalgal biomass are fermented to short-chain fatty acids, while the existing lipid fraction is conserved in a form that is more readily extracted from the non-fermented biomass. To increase the rate and extent of carbohydrate and protein fermentation, the selective fermentation process will be carried out in the anode chamber of a microbial electrolysis cell (MEC), which produces hydrogen gas at the cathode, consumes the fermentation products, and promotes bio-hydrogenation of unsaturated fatty acids to saturated fatty acids with higher fuel quality. Mathematical models will be developed to link the key biochemical, microecological, and electrochemical mechanisms to improve fundamental understanding of the interactions of these processes in the overall system, and will enable future techno-economic and life-cycle analysis of the process. The education aspects of this project will advance the development of a green workforce by involving students from under-represented groups at a local community college in year-round research experiences, and by supporting a high school teacher and student in paired summer internships.