Induction and stability of alcohol oxidase in the methylotrophic yeast Pichia pastoris

Abstract

Alcohol oxidase biosynthesis was induced when Pichia pastoris was grown in a medium containing methanol as the sole carbon and energy source. Specific activity was highest during the logarithmic phase of growth (1.22 g acetaldehyde produced/g cell dry wt. per hour), and declined steadily thereafter. The addition of 0.1% (w/v) yeast extract to the methanol growth medium promoted higher biomass production, increased alcohol oxidase specific activity, and contributed to increased enzyme stability under use conditions. When P. pastoris was used for wholecell bioconversions, 30.2 g of ethanol were oxidized to 28 g acetaldehyde in 12 h, at a carbon recovery of 97%. Acetaldehyde concentrations in excess of 1 M were achieved when the concentration of the TRIS buffer, used to chemically trap the acetaldehyde, was increased to 1 M.