Enhanced Production of 2,3-Butanediol by Yeast through Overcoming Metabolic Limitations

2,3-Butanediol (2,3-BD) is a promising compound with various applications in several industries. Pyruvate decarboxylase (Pdc)-deficient Saccharomyces cerevisiae is an attractive host for 2,3-BD production due to large amounts of pyruvate available. However, the productivity of an engineered Pdc-deficient S. cerevisiae was inferior due to metabolic limitations, such as growth defects caused by a shortage of C₂-compounds as well as redox imbalance during the 2,3-BD production, leading to glycerol formation and lower 2,3-BD yield.

To overcome these problems, a team of researchers led by Jin-Woo Kim from Seoul National University, optimized CtPDC1 from Candida tropicalis in S. cerevisiae. The expression of CtPDC1 minimized ethanol production as well as cell growth and 2,3-BD production. The productivity of the resulting strain, BD5_G1CtPDC1, was found to be 2.3 times higher than the control strain in flask cultivation. NADH oxidase from Lactococcus lactis (noxE) was then additionally expressed in the engineered yeast.

A massive metabolic shift in the engineered S. cerevisiae BD5_G1CtPDC1_nox, expressing bot Pdc and NADH oxidase, was observed, suggesting that redox imbalance was a major hindrance for efficient production of 2,3-BD by engineered yeast. These results demonstrate that resolving the metabolic limitations is critical in increasing 2,3-BD production in the Pdc-deficient S. cerevisiae.