Co-Production of Hydrogen and Ethanol by Engineered Escherichia coli

Fermentative hydrogen (H₂) production suffers from low carbon-to-H₂ yield. Hence, a co-production of ethanol and H₂ has been proposed as a solution.

For improved co-production of H₂ and ethanol, the team of Balaji Sundara Sekar and Eunhee Seol from Pusan National University in South Korea developed Escherichia coli BW25113 (SH*ZG). The developed strain had overexpressed Zwf and Gnd, key enzymes in the pentose-phosphate (PP) pathway. However, the amount of accumulated pyruvate reduced the co-production yield.

To reduce pyruvate accumulation and improving co-production of H₂ and ethanol, the team developed another strain, E. coli SH9*_ZG, with functional acetate production pathway to consume the pyruvate. The presence of the acetate pathway completely eliminated pyruvate accumulation and substantially improved the co-production of H₂ and ethanol.

This strategy is applicable for anaerobic production of biofuels and biochemicals.