(41e) Engineering Biosynthetic Pathways and Improving Solvent Productivities in Clostridium Acetobutylicum Toward the Production of Biodiesel Blendstocks and High-Value Chemicals

Advancements in metabolic engineering have facilitated the biological conversion of carbohydrates into various jet and diesel fuel compounds, albeit at low yields and titers that hinder their production at the industrial level. Recently, our team developed a chemocatalytic technology to efficiently condense electrophilic alcohols with nucleophilic ketones – specifically, the acetone, n-butanol, and ethanol products from Clostridium acetobutylicum – for creating jet fuel and biodiesel blendstocks. Several features of Clostridia including their flexibility towards fermentable substrates, high solvent titers, and yields near the theoretical maxima have contributed to the resurgence of these microbes and the ABE fermentation for producing biofuels at the industrial scale. In this work, we describe the engineering of Cl. acetobutylicum via the recombinant co-expression of both native and heterologous proteins. Specifically, we discuss our progress with alleviating product toxicity, increasing solvent titers and productivities in batch and fed-batch fermentations, and introducing non-native biosynthetic pathways for making new metabolic products. We also discuss how our engineered strains, in combination with the chemocatalytic technology that we have developed, demonstrate a promising step toward establishing industrially relevant microbial processes for the production of jet fuel and diesel blendstocks as well as other high-value products.