Demonstration and technoeconomic analysis of dodecanol production from acetate using metabolically engineered...

In a circular bioeconomy, the one-way conversion of petroleum to chemicals and CO₂ is replaced with processes that reduce CO₂ to energy carriers and useful materials that are returned to CO₂ upon combustion. A circular bioeconomy that relies on photosynthesis to generate sugars as the chief energy carrier and precursor to chemical building blocks has yet to overcome many recalcitrant aspects of plant-based photosynthesis, namely, high feedstock costs, arable land scarcity, food competition, and fertilizer overuse. Acetate is a potential sustainable energy carrier because it can be produced from CO₂ either electrocatalytically or by acetogens via the Wood-Ljungdahl pathway. In this work, we conducted a metabolic engineering study of Escherichia coli's ability to convert acetate into dodecanol as a model oleochemical product. We performed techno-economic and life cycle analyses to determine break-even points with alternative fossil fuel-based strategies and identified critical process performance parameters for supporting an industrial acetate-based bioprocess. These analyses showed that oleochemical yield is the primary driver of minimum oleochemical selling price and carbon intensity. Therefore, to increase yield on acetate, we deleted the aceBAK operon, which facilitates funneling of acetate into biomass instead of product. We performed additional strain engineering to increase flux towards dodecanol and increase acetate uptake. Finally, we demonstrated increased yield in controlled bioreactors, improving from 13 % of the maximum theoretical yield to 37 %. Rigorous uncertainty analyses assuming a range of market conditions and future technological performances resulted in 88 % and 37 % of simulated scenarios having lower carbon intensities than fossil fuel-based routes and lower minimum selling prices than the market price.