Production of pyruvate in Saccharomyces cerevisiae through adaptive evolution and rational cofactor metabolic engineering

Pyruvate-decarboxylase (Pdc)-negative Saccharomyces cerevisiae has been proven as a suitable metabolic engineering platform to produce organic acids. S. cerevisiae BY5419 Pdc− strain cannot grow in batch cultures on synthetic medium with glucose as the sole carbon source, yet grows well on synthetic medium with ethanol or acetate. In this study, by combining adaptive evolution and cofactor engineering, we obtained a series of engineered yeasts that can produce pyruvate using glucose as sole carbon source. Differential expression of noxE, encoding a water-forming NADH oxidase from Lactococcus lactis, and udhA, encoding a soluble pyridine nucleotide transhydrogenase from Escherichia coli, was investigated. Of all the constructed recombinant strains, G2U1-A0 was able to produce 75.1 g l−1 pyruvate, increased 21% compared with the original strain A0. The production yield of this strain reached 0.63 g of pyruvate g of glucose−1. This study demonstrates that the fine regulation of intracellular NADH/NAD+ ratio is critical for cell metabolism and pyruvate production. Combining the adaptive evolution and fine regulation of intracellular NADH/NAD+ ratio provides a new strategy for improving the Pdc− strain engineering platform.

► Combining adaptive evolution and cofactor engineering obtained engineered yeasts.
► G2U1-A0 was able to produce 75.1 g l−1 pyruvate.
► Differential expression of noxE and udhA was investigated.
► Fine regulation of NADH/NAD+ ratio is critical to pyruvate production.
► A new strategy for improvement of the Pdc− strain engineering platform is provided.