Metabolic engineering of Saccharomyces cerevisiae for accumulating pyruvic acid

Annals of Microbiology

Table 3 Pyruvic acid yields and theoretical yields of strains Y2, Y2-1, and Y2-15 in fermentation broth

Strain	Pyruvic acid (g/L)	OD₆₀₀	Residual glucose (g/L)	Theoretical yield [pyruvic acid/total glucose (%)]
Y2	1.38 ± 0.04	0.97 ± 0.01	2.34 ± 0.12	1.7 %
Y2-1	3.51 ± 0.07	0.77 ± 0.02	5.72 ± 0.10	4.3 %
Y2-15	24.65 ± 0.05	0.65 ± 0.01	8.89 ± 0.09	30.8 %
Torulopsis glabrata (Li et al. 2002)	46.36 ± 0.05			48.3 %

Note: The inoculum culture (10 % v/v) was then inoculated into 500 mL flasks containing 50 mL of fermentation medium. Fermentation of pyruvic acid was carried out in flasks at 30 °C and shaken at 200 rpm for 96 h. The concentration of pyruvic acid in the fermentation broth was determined by HPLC with an organic acid column (Bio-Rad). The mobile phase was a 0.5-mM H₂SO₄ aqueous solution at a flow rate of 0.6 mL/min and injection volume of 25 μL. The wavelength of the UV detector was set at 210 nm, and the column temperature was controlled at 50 °C. Glucose was determined using a biosensor (SBA-40C). Yeast cell growth (biomass) was measured turbidimetrically at 660 nm (OD₆₆₀) after the culture broths was diluted 50-fold with water. All experiments were performed in triplicate.

ISSN: 1869-2044