Genetically Engineered Wine Yeast Produces a High Concentration of l -Lactic Acid of Extremely High Optical Purity

For mass production of lactic acid, we newly constructed a transgenic wine yeast strain that included six copies of the bovine L-lactate dehydrogenase gene on the genome. On fermentation in inexpensive cane juice-based medium, L-lactate production of this recombinant reached 122 g/liter and the optical purity was 99.9% or higher.