Experimental and theoretical trait-based approaches to optimizing algal biofuel polycultures

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PI: LitchmanProposal Number: 1134215Intellectual MeritMicroalgae are a promising renewable feedstock for sustainable biofuel production, and offer several unique advantages for this purpose, including high growth rate and photosynthetic efficiency, use of marginal land for lipid-rich biomass production, potential use of wastewater as a nutrient source, and relatively low energy requirements for converting its biomass (lipids) into biofuel (biodiesel). Approaches to intensification of algal biofuel production typically focus on identifying and growing monocultures of microalgal species shown to produce high amounts of lipids. However, these monocultures, because of inherent physiological trade-offs, may not utilize nutrients and light for maximum efficiency, are susceptible to invasions by other species, and can exhibit fluctuations in biomass and lipid productivity. In contrast, microalgal polycultures can potentially circumvent these eco-physiological tradeoffs and provide a more robust platform for algal biofuels production, particularly in scalable open cultivation systems. The overall goal of the proposed research is to design multispecies microalgal communities that optimize resource utilization, biomass production, and lipid accumulation under changing environmental conditions while providing increased resistance to pathogens and invasions by nuisance species. Towards this end, the diverse eco-physiological traits of many algal species will be analyzed to deduce the trade-offs among these traits, and from this analysis, the appropriate species for microalgal consortia will be identified that maximize multiple goal functions under process constraints. Mathematical models, combined with laboratory experiments for parameter estimation and model validation, will be used to assess the dynamic behavior of the designed polyculture communities, and identify those with best performance characteristics relative to their respective monocultures. The most promising microalgal communities will be further investigated for scalability using enclosed photobioreactors and open pond cultivation systems.Broader ImpactsThe proposed education and outreach activities will offer K-12 student and teacher experiences in bioenergy topics through the Kellogg Biological Station (KBS) GK-12 Bioenergy Sustainability Project, which engages local rural schools in ecological and sustainability research. The PI will host a high school teacher during the summer to develop age-appropriate, hands-on educational modules on bionergy, sustainability, and aquatic ecology. A postdoctoral associate will be trained in interdisciplinary research combining mathematical modeling, ecological principles, and bioenergy applications, and will interact with the researchers from the Great Lakes Bioenergy Research Center (GLBRC) to exchange ideas on the use of polycultures for biofuel production.