Pyruvate Production from Whey Powder by Metabolic Engineered .

Pyruvate is an important platform material widely used in food, pharmaceutical, and chemical industries. Pyruvatetolerant PDL-0 was chosen as a chassis for pyruvate production via metabolic engineering. Genes related to by-product generation were knocked out to decrease the production of 2,3-butantediol, acetate, ethanol, and succinate. The NADH oxidase encoding gene was inserted into the locus of the lactate dehydrogenase encoding gene in the genome of to simultaneously block lactate production and regenerate NAD. The pyruvate importers CstA and YjiY were identified, and their encoding genes were deleted to increase pyruvate accumulation. The engineered strain PDL-YC produced 71.0 g/L pyruvate from glucose. Furthermore, PDL-YC can use whey powder, an abundant by-product of the cheese making process, as substrate for pyruvate production. Pyruvate production with a concentration of 62.3 g/L and a productivity of 1.60 g/[L·h] was realized using whey powder as substrate.