ABSTRACT
High levels of active glycolate oxidase from spinach (GO) and active catalase T from Saccharomyces cerevisiae (catT) have been co-produced in the methylotrophic yeast Pichia pastoris (Pp). In sequential rounds of transformation using two selectable markers, multiple copies of the genes encoding GO and catT were integrated into the Pp chromosome under control of the methanol inducible alcohol oxidase I promoter, resulting in a strain designated MSP8.6. MSP8.6 is a second-generation biocatalyst used for the conversion of glycolate to glyoxylate in the presence of a reaction component which inhibits endogenous Pp catalase. This work demonstrates a significant advance in the utility of recombinant Pp for commercial bioprocess development.
Subject(s)
Alcohol Oxidoreductases/biosynthesis , Catalase/biosynthesis , Fungal Proteins/biosynthesis , Pichia/genetics , Plant Proteins/biosynthesis , Alcohol Oxidoreductases/genetics , Catalase/genetics , Catalysis , Cloning, Molecular/methods , Enzyme Activation , Fungal Proteins/genetics , Genetic Engineering , Plant Proteins/genetics , Recombinant Fusion Proteins/biosynthesis , Recombinant Fusion Proteins/genetics , Spinacia oleracea , Transformation, GeneticABSTRACT
Glycolate oxidase (GO) is a flavo-enzyme that catalyzes the oxidation of glycolate, and is useful for the biocatalytic production of glyoxylate. We have produced high levels of spinach GO in the methylotrophic yeast Pichia pastoris (Pp), by chromosomal integration of multiple copies of an expression cassette containing the GO coding sequence under control of the methanol-inducible alcohol oxidase I promoter. Under fermentation conditions, greater than 250 units of GO per gram of cells (wet weight) was obtained, corresponding to roughly 20-30% of soluble cell protein. This recombinant Pp strain was used as a whole-cell biocatalyst for conversion of glycolic acid to glyoxylic acid.
