Our approach was to use genetically engineered S. cerevisiae to develop a fermentation based method for glycolic acid production. Glycolic acid can be produced in the glyoxylate cycle where glyoxylate can be further converted to glycolic acid. S. cerevisiae has a gene coding for glyoxylate reductase but in order to make the conversion more efficient we overexpressed an NADPH specific glyoxylate reductase from Arabidobsis thaliana for converting glyoxylate to glycolic acid.
For efficient conversion of glyoxylate into glycolic acid and boosting up the glyoxylate cycle also further modifications were made. Two malate synthase genes were deleted to prevent glyoxylate to react to malate. Additionally steps leading to glyoxylate formation were boosted by overexpressing isocitrate lyase and aconitase. Also the influence of regulatory factors, effect of ethanol metabolism and acetyl-CoA and NADPH availability were tested. The resulting strains were cultivated in shake flasks in different media and the production of glycolic acid was demonstrated.