Construction of reductive pathway in Saccharomyces cerevisiae for effective succinic acid fermentation at low pH value.

Succinic acid is an important precursor for the synthesis of high-value-added products. Saccharomyces cerevisiae is a suitable platform for succinic acid production because of its high tolerance towards acidity. In this study, a modified pathway for succinate production was established and investigated in S. cerevisiae. The engineered strain could produce up to 6.17±0.34g/L of succinate through the constructed pathway. The succinate titer was further improved to 8.09±0.28g/L by the deletion of GPD1 and even higher to 9.98±0.23g/L with a yield of 0.32mol/mol glucose through regulation of biotin and urea levels. Under optimal supplemental CO2 conditions in a bioreactor, the engineered strain produced 12.97±0.42g/L succinate with a yield of 0.21mol/mol glucose at pH 3.8. These results demonstrated that the proposed engineering strategy was efficient for succinic acid production at low pH value.