Increased CO2 Fixation Enables High Carbon-Yield Production of the Acrylic Acid Precursor 3-Hydroxypropionic Acid in Yeast

Abstract CO2 fixation plays a key role to make biobased production cost competitive. Here, we used 3-hydroxypropionic acid (3-HP) to showcase how CO2 fixation enabled approaching theoretical-yield production. Using genome-scale metabolic models to calculate the production envelope, we demonstrated that the provision of bicarbonate, formed from CO2, sealed previous attempts for high yield production of 3-HP. We thus developed multiple strategies for bicarbonate uptake, including the identification of Sul1 as a bicarbonate transporter, domain swapping and engineering of malonyl-CoA reductase, identification of Esbp6 as a 3-HP exporter, and deletion of Uga1 to prevent 3-HP degradation. The combined rational engineering increased 3-HP production from 0.15 g/L to 11.25 g/L in shake-flask using 20 g/L glucose, approaching the maximum theoretical yield with concurrent biomass formation. The engineered yeast forms the basis for commercialization of bio-acrylic acid, while our CO2 fixation strategies pave the way for CO2 being used as the sole carbon source.