Systems-Level Analysis of Saccharomyces Cerevisiae Engineered for Production of 3-Hydroxypropionic Acid

Authors: 
Schneider, K., Technical University of Denmark
Czarnotta, E., RWTH Aachen University
Özdemir, E., Technical University of Denmark
Klein, T., Technical University of Denmark
Christensen, H. B., Technical University of Denmark
Kim, I. K., Chalmers University of Technology
Forster, J., Technical University of Denmark

Biologically produced 3-hydroxypropionic acid (3HP) is a potential source for sustainable acrylates and can also find direct use as monomer in the production of biodegradable polymers. For an economically viable process 3HP must be produced at high titer, rate and yield and preferably at low pH to minimize downstream processing costs. In this study, we engineered S. cerevisiae for high-level production of 3HP via a malonyl-CoA reductase (MCR)-dependent pathway by increasing the copy numbers of biosynthetic genes and improving flux towards precursors and redox cofactors. The final strain produced 9.8 g·L-1 3HP with a yield of 13% C-mol·C-mol-1 glucose after 100 hours at pH 5 in carbon-limited fed-batch cultivation. The best 3HP-producing strain was further characterized by transcriptome analysis and 13C metabolic flux analysis, which revealed several unexpected consequences of the undertaken metabolic engineering strategies. In conclusion, our study demonstrated that in strain engineering it is not sufficient to look at the resulting product titers, but one needs more in-depth characterization of the cellular physiology and cellular components and fluxes in order to follow and advance the strain development.