In-fusion expression and characterization of β-xylanase and β-1,3-1,4-glucanase in Pichia pastoris

Two chimeric genes, XynA-Bs-Glu-1 and XynA-Bs-Glu-2, encoding Aspergillus sulphureus beta-xylanase (XynA, 26 kDa) and Bacillus subtilis beta-1,3-1,4-glucanase (Bs-Glu, 30 kDa), were constructed via in-fusion by different linkers and expressed successfully in Pichia pastoris. The fusion protein (50 kDa) exhibited both beta-xylanase and beta-1,3-1,4-glucanase activities. Compared with parental enzymes, the moiety activities were decreased in fermentation supernatants. Parental XynA and Bs-Glu were superior to corresponding moieties in each fusion enzymes because of lower K-n higher k(cat). Despite some variations, common optima were generally 50A degrees C and pH 3.4 for the XynA moiety and parent, and 40A degrees C and pH 6.4 for the Bs-Glu counterparts. Thus, the fusion enzyme XynA-Bs-Glu-1 and XynA-Bs-Glu-2 were bifunctional.