Rational Metabolic Engineering of Baker's Yeast for Production of 3-Hydroxypropionic Acid

Metabolic engineering distinguishes itself from the classical engineering disciplines, such as electrical or chemical engineering, by lower predictability of design outcome and long turnover times of the build and testphases. This situation has however been rapidly improving over the past two decades.* Advanced systems biology and genome-scale modeling approaches allow more precise simulations of the complex biological systems, thus improving predictions of the metabolic engineering targets. The novel synthetic biology tools accelerated genome editing and enabled high-throughput screening using synthetic signaling circuits, i.e., biosensors.

We engineered baker's yeast for production of 3-hydroxypropionic acid (3HP). 3HP can be chemically dehydrated into acrylic acid and thus serve as a biosustainable building block for acrylate-based products (diapers, acrylic paints, acrylic polymers, etc.) We considered several biosynthetic pathways leading to 3HP, screened for efficient enzyme variants and optimized gene expression using novel synthetic biology tools that we developed for stable single and multi-copy integration of genes into the yeast genome. Engineering of precursor and co-factor supply by using both rational and model-guided approaches and optimizing fermentation parameters helped to further improve 3HP titer, production rate and yield. Adaptive laboratory evolution followed by genome re-sequencing, transcriptome analysis and reverse engineering allowed to decipher 3HP tolerance mechanism.

In summary, we show how modern synthetic biology and metabolic engineering tools enable rapid strain optimization in iterative design-build-test cycles.

*Borodina I, Nielsen J (2014). “Advances in Metabolic Engineering of Yeast for Production of Chemicals”. Biotechnol J. DOI: 10.1002/biot.201300445