Bioprocess intensification for 3-hydroxypropionic acid production from methanol using engineered Komagataella phaffii

Green methanol is increasingly recognized as an attractive feedstock to produce value-added biochemicals, providing a unique opportunity to positively impact sustainability. The methylotrophic yeast Komagataella phaffii has been recently engineered for 3-hydroxypropionic acid (3-HP) production from methanol. However, challenges remain in developing techno-economically viable and environmentally sustainable bioprocesses. In this study, different fed-batch operational strategies and conditions, using K. phaffii strain engineered with the synthetic β-alanine pathway to produce 3-HP, based on a preprogrammed exponential feeding of methanol to attain a constant specific growth rate or a closed-loop feedback control of methanol concentration were implemented and compared. The latter strategy resulted in better overall process performance, reaching a 3-HP concentration of 42.7 g 3-HP /L in the supernatant, a yield on methanol of 0.106 g 3-HP /g S and a volumetric productivity of 0.495 g 3-HP /(L·h). Additionally, the use of formate as an electron donor in methanol fed-batch cultures were investigated, demonstrating improved process efficiency (final product concentration, yield on methanol and volumetric productivity increase of about 15%). Overall, the results obtained in this study highlight the potential of K. phaffii as a methanol-based platform microbial cell factory, paving the way for further bioprocess intensification for sustainable chemicals production from CO 2 -derived feedstocks.