(359f) Integrated Conversion of Algal Biomass to Fusel Alcohols and Optimization of Alcohol Mixture Composition for Maximum Fuel Economy/Efficiency in Light Duty Vehicles

A key challenge for use of algae biomass for renewable fuels is efficient utilization of all of the major biochemical fractions of the biomass, including carbohydrates, proteins, and lipids. Development of a combined algae processing biorefinery would facilitate co-production of petroleum displacing chemicals with the intermediate to high value products that are currently produced from algae. To overcome issues involved with highly variable feedstock composition, our group is developing means for single-pot bioconversion of amino acid and sugar oligomers from algae hydrolysates to generate a variety of petroleum-displacing end products. Through these efforts we have recently demonstrated pretreatment and bioconversion of a variety whole algae hydrolysates, including raceway-cultivated Nannochloropsis sp., Scenedesmus obliquus, filamentous periphyton obtained from algae turf flow ways, and others. To enable high efficiency utilization of multiple fermentation substrates, we have developed an engineered E. coli biocatalyst consortium with each cohort optimized for utilization of either sugar or amino acid oligomers. Using this strategy, we have demonstrated production of fusel alcohols from diverse algae biomass and found that retention of algal lipids in the bioprocessing provides process intensification benefits by alleviating product inhibition and allowing co-extraction of the algae derived products. Furthermore, we have developed an optimization platform to evaluate the optimal alcohol mixture to maximize fuel performance and better inform further biocatalyst development. Our results demonstrate that an optimized solution has the potential to increase the change in total fuel economy of a light duty vehicle by more than 10% at high blend volumes compared to an unoptimized mixture. Optimal solutions can be tailored toward greatest increasing in vehicle fuel economy, or greatest thermodynamic efficiency gain/greatest CO2 reductions. This work discusses these trade-offs and their implications for algae cultivation and conversation technologies at large.