Ambient Alkaline Pretreatment Enables Isoprenol Fermentation from Lignocellulosic Biomass for Sustainable Aviation Fuel Production

Abstract

Abstract Mitigating aviation’s carbon emissions remains challenging because air travel relies on energy-dense liquid fuels with limited substitutes. Here, we report a fermentation-based bioconversion process for producing isoprenol, a precursor to 1,4-dimethylcyclooctane (DMCO), a sustainable aviation fuel blendstock with Jet-A-comparable fuel properties and O-ring swelling behavior, which can substitute for aromatic additives and derived from lignocellulosic biomass at 25 °C. Ambient alkaline pretreatment achieved greater than 89% xylan deacetylation and 79–93% glucan digestibility across all feedstocks, without the formation of furan inhibitors. An engineered Escherichia coli strain directly fermented the unpurified biomass hydrolysate to isoprenol without requiring hydrolysate detoxification, demonstrating compatibility of the alkaline pretreatment stream with the fermentation step. The ambient pretreatment conditions produced no detectable furfural or HMF, enabling an isoprenol titer of 0.38 g/L (28 mg/g sugar consumed), comparable to pure sugar controls. This biochemical process is effective across corn stover, rice straw, and hemp hurd. This work establishes ambient alkaline pretreatment as a low-energy approach compatible with direct microbial isoprenol production across diverse feedstocks, providing a reduced-step route toward lignocellulose-derived sustainable aviation fuel.