Discipline: Biological Sciences
Jasmine Winzeler - Eastern Michigan University
Co-Author(s): Diamond Jones, Eastern Michigan University, Ypsilanti, MI
Algal biofuel is a promising source of renewable energy. However, in order for algal biofuel to become economical and commercially viable, we need to maximize algal yields while simultaneously minimizing use of fertilizers that represent a high input cost. It has been proposed that fertilizer use can be decreased by growing algal consortia (combinations of species), which can generally utilize fertilizers more efficiently, and yield more biomass than single-species monocultures. We tested the hypothesis that species consortia produce greater biomass yields across a wider range of fertilizer exchange frequencies and dilution rates than their component species grown in monoculture. To test this hypothesis, we conducted a laboratory experiment in assay plates using six algal monocultures and nine bicultures that were grown in high nutrient Bold 3N media. Zero to 50 percent of growth media was exchanged every one to 32 days, and chlorophyll fluorescence was measured to estimate algal biomass yields. Monocultures of the highest yielding species (Scenedesmus acuminatus) achieved peak biomass over dilution rates ranging from 0% to 20%, and exchange frequencies ranging from every day to every eight days, with the highest peak biomass on day 34. Species consortia achieved their peak biomass yields over a wider range of conditions. The best biculture (Ankistrodesmus falcatus and S. acuminatus) reached peak biomass over dilution rates ranging from 0% to 50% and exchange frequencies ranging from every day to every two, four, eight, and 32 days, with the highest peak biomass on day 32 of the experiment. Bicultures typically exhibited peak biomass 17% lower than monocultures, however the maximum monoculture biomass yield (observed only under a narrow range of optimal conditions) was nearly twice the maximum biculture biomass yield. Overall, peak biomass of the A. falcatus and S. acuminatus biculture was reached over the entire range of treatment conditions three days sooner than S. acuminatus alone. Our research suggests that growing species consortia could help improve the efficiency of algal biofuel culture systems, as they can yield similar amounts of biomass as current monoculture systems, but in a shorter timeframe and under a wider range of fertilizer conditions.
Funder Acknowledgement(s): This work was funded by a Research Experience and Mentoring (REM) supplement to grant 1332342 from NSF’s Emerging Frontiers in Research and Innovation (EFRI) Program. The supplement supported development of an undergraduate internship program co-run by Dr. Bradley Cardinale (University of Michigan) and Dr. Steve Francoeur (Eastern Michigan University).
Faculty Advisor: Brad Cardinale,