Expression of an Aspergillus niger xylanase in yeast: Application in breadmaking and in vitro digestion

The cDNA of the beta-1,4-endoxylanase of Aspergillus niger US368 was cloned and expressed in Pichia pastoris under the constitutive GAP promoter. The maximum activity obtained was 41 U mL(-1), which was about 3-fold higher than that obtained with the native species. The purified enzyme showed a specific activity of 910U mg(-1) and a molecular mass of 24 kDa. It had an optimal activity at pH 4 and 50 degrees C, stable in a wide range of pH and in the presence of some detergents and organic solvents. r-XAn11-His(6) (recombinant xylanase) was used as an additive in breadmaking. A decrease in water absorption, an increase in dough rising and improvements in volume and specific volume of the bread were recorded. The r-XAn11-His(6) was also used in in vitro digestion of barley and wheat bran leading to a decrease of the viscosities and an increase of the reducing sugars and total sugars contents. (C) 2015 Elsevier B.V. All rights reserved.