Prospects of Direct Microbial Conversion of Sugars to Acrylic Acid in a Sugarcane Biorefinery: Techno-Economic and Environmental Comparison of Conventional and Extractive Fermentation

Abstract

Abstract Production of acrylic acid (AA) via direct microbial conversion of sugars may offer substantial economic and environmental benefits compared to indirect sugars conversion via chemical intermediates. However, further improvements to the performances of direct microbial bioconversions are required to allow industrial large-scale implementation. The benefits in terms of minimum selling price (MSP) and greenhouse gas (GHG) emissions associated with such improvements to bioprocess performances were assessed through a Full-factorial (FF) assessment. Aspen Plus® simulations of direct sugars conversion to AA in a biorefinery retrofitted to a typical sugarcane mill were built using either conventional fermentation (S1-AA-CF) or extractive fermentation (S2-AA-EF). At current-best performances the MSP of S2-AA-EF is 25 times lower than for S1-AA-CF, while having 97.5% fewer GHG emissions. The lowest achievable MSPs from feasible improvements to microbe and bioprocess performances for S1-AA-CF and S2-AA-EF were 65.4% and 29.6% below the fossil-based price, respectively. The desired performance of the conventional fermentation route is dependent on strain engineering to alleviate AA product-inhibition, allowing for titres of 52 g AA . L −1 or more to be achieved in a fed-batch bioprocess. Thus, extractive fermentation is recommended as the preferred route for direct microbial conversion of sugars to AA. Graphical Abstract