GLYOXYLIC-ACID PRODUCTION USING MICROBIAL TRANSFORMANT CATALYSTS

A practical method for the biocatalytic oxidation of glycolic acid to glyoxylic acid which uses a genetically engineered microbial cell as c atalyst has been developed. Oxidations of glycolic acid at concentrati ons ranging from 0.75 to 1.5 M were run in aqueous solution in the pre sence of oxygen, ethylenediamine, and a metabolically inactive transfo rmant of Aspergillus nidulans, Hansenula polymorpha, Pichia pastoris, or Escherichia coli. Each of the transformant catalysts contained sign ificant quantities of both spinach glycolate oxidase ((S)-2-hydroxy ac id oxidase, EC 1.1.3.15) and an endogenous catalase (EC 1.11.1.6). The H. polymorpha and P. pastoris transformant catalysts were recycled in up to 30 consecutive batch reactions, where the selectivity to glyoxy lic acid was typically >98% at 100% conversion of glycolic acid. Under optimum reaction conditions and with endpoint monitoring, selectiviti es to glyoxylic acid of at least 99.7% were obtained.