Engineering of Saccharomyces cerevisiae for enhanced metabolic robustness and L-lactic acid production from lignocellulosic biomass
Journal article, 2024

Metabolic engineering for high productivity and increased robustness is needed to enable sustainable biomanufacturing of lactic acid from lignocellulosic biomass. Lactic acid is an important commodity chemical used for instance as a monomer for production of polylactic acid, a biodegradable polymer. Here, rational and model-based optimization was used to engineer a diploid, xylose fermenting Saccharomyces cerevisiae strain to produce L-lactic acid. The metabolic flux was steered towards lactic acid through the introduction of multiple lactate dehydrogenase encoding genes while deleting ERF2, GPD1, and CYB2. A production of 93 g/L of lactic acid with a yield of 0.84 g/g was achieved using xylose as the carbon source. To increase xylose utilization and reduce acetic acid synthesis, PHO13 and ALD6 were also deleted from the strain. Finally, CDC19 encoding a pyruvate kinase was overexpressed, resulting in a yield of 0.75 g lactic acid/g sugars consumed, when the substrate used was a synthetic lignocellulosic hydrolysate medium, containing hexoses, pentoses and inhibitors such as acetate and furfural. Notably, modeling also provided leads for understanding the influence of oxygen in lactic acid production. High lactic acid production from xylose, at oxygen-limitation could be explained by a reduced flux through the oxidative phosphorylation pathway. On the contrast, higher oxygen levels were beneficial for lactic acid production with the synthetic hydrolysate medium, likely as higher ATP concentrations are needed for tolerating the inhibitors therein. The work highlights the potential of S. cerevisiae for industrial production of lactic acid from lignocellulosic biomass.

Lactic acidYeastXyloseSaccharomyces cerevisiaeRobustnessMetabolic engineeringMetabolic modeling

Author

BoHyun Choi

Chalmers, Life Sciences, Industrial Biotechnology

Albert Tafur Rangel

Chalmers, Life Sciences, Systems and Synthetic Biology

Novo Nordisk Foundation

Eduard Kerkhoven

Chalmers, Life Sciences, Systems and Synthetic Biology

Novo Nordisk Foundation

Science for Life Laboratory (SciLifeLab)

Yvonne Nygård

Chalmers, Life Sciences, Industrial Biotechnology

Technical Research Centre of Finland (VTT)

Metabolic Engineering

1096-7176 (ISSN) 1096-7184 (eISSN)

Vol. 84 23-33

Bioplastics and wax esters from wood through co-culture of bacteria and yeast

Formas (2019-02510), 2020-04-01 -- 2022-03-31.

J. Gust. Richert stiftelse (2022-0073), 2023-01-01 -- 2023-12-31.

Subject Categories

Biochemicals

Bioinformatics (Computational Biology)

DOI

10.1016/j.ymben.2024.05.003

More information

Latest update

6/10/2024