Characterization and application of a glycolate dehydrogenase from Trichoderma harzianum AIU 353

A glycolate dehydrogenase (GADH), which catalyzes oxidation of glycolic acid to glyoxylic acid, was found from a newly isolated fungus, Trichoderma harzianum AIU 353. The dehydrogenase reaction required nitro blue tetrazolium or 2,6-dichlorophenolindophenol, but not NAD+ and NADP+ as an electron carrier. Methylglycolate, glycolaldehyde, l-lactic acid, glyceraldehyde and dihydroxyacetone were also oxidized, but primary alcohols, dihydric alcohols and aliphatic aldehydes were not. The Km values for glycolic acid, l-lactic acid and dihydroxyacetone were estimated to be 0.94 mM, 3.6 mM and 49.5 mM, respectively. The GADH activity was optimum at pH 7.0 and 30 °C. The molecular mass of this enzyme was 280 kDa consisting of four subunits with molecular mass of 107, 81, 53 and 38 kDa. These characteristics of the fungal GADH are remarkably differentiated from those of other GADHs. The enzyme and cells were applicable for the production of glyoxylic acid from glycolic acid.