Production of Lactate in Escherichia coli by Redox Regulation Genetically and Physiologically

Escherichia coli grows fermentatively in glucose-containing medium under anaerobic condition with formation of a mixture of organic acids (lactate, acetate, formate, and succinate) and ethanol to accommodate reducing equivalents generated during glycolysis. In this paper, we tried to improve the lactate accumulation in E. coli by redox regulation genetically and physiologically. Our results indicated that genetic regulation of the host by reducing the reductive by-product may improve the lactate production. In addition, lactate accumulation was also improved under reduced and anaerobic cultivation conditions. Engineered E. coli SDU4 was able to accumulate lactate under strictly anaerobic conditions to 100 g/L with a yield of 1.97 mol/mol glucose.