Abstract:

Enzymolysis of using dextranase is the best way to the removal of dextrans that result in sugar loss,manufacture difficulty and quality decline during the sugar manufacture. In this paper,dextranase gene dex was cloned into a yeast constitutive expression vector pGAPZαA,and the recombinant plasmid pGAPZαA-dex was transformed into Pichia pastoris KM71H to construct an engineering strain constitutively expressing dextranase. After the
cultivation for 120 h in a shake flask,dextranase with an activity of 60.4U/mL was successfully obtained,thus implementing the constitutive expression of dextranase in Pichia pastoris. The proposed method avoids the use of methanol during the fermentation,which helps to improve the production and use safety during the sugar manufacture.

Key words: sugar manufacture, dextranase, constitutive expression, Pichia pastoris, fermentation