Co-immobilization and stabilization of xylanase, β-xylosidase and α-l-arabinofuranosidase from Penicillium janczewskii for arabinoxylan hydrolysis

• Xylanolytic enzymes cooperatively degrade complex hemicellulosic polysaccharides.
• Glutaraldehyde support rendered good balance in the concomitant immobilization of the enzymes.
• Additional coating with low molecular weight dextran stabilize enzymes in the support.
• Derivative coated with dextran at intermediate degree of oxidation is the most stable one.
• Xylose release is observed from the hydrolysis of different arabinoxylan with the immobilized enzymes.

Differently activated agarose-based supports were evaluated for co-immobilization of a crude extract from Penicillium janczewskii containing xylanase, β-xylosidase and α-l-arabinofuranosidase activities. Adequately selecting support and immobilization conditions (8 h, using agarose with 10% crosslinking) increased enzyme levels substantially, mainly in relation to the xylanase (2-fold). A coating with dextran aldehyde MW 6000 Da, partially oxidized, covalently attached the enzymes to the support. Optimum activity was verified in the pH range 2–4, and at 50, 65 and 80 °C for the xylanase, α-l-arabinofuranosidase and β-xylosidase, respectively. The xylanase was highly thermostable retaining more than 70% of activity even after 24 h incubation at 60 and 70 °C; and at 80 °C its half-life was 1.7 h. The half-lives of the β-xylosidase and α-l-arabinofuranosidase at 50 °C were 2.3 and 3.8 h, respectively. The co-immobilization of the enzymes on a single support give raise to a functional multi-enzymatic biocatalyst acting in the complete hydrolysis of different and complex substrates such as oat spelt and wheat arabinoxylans, with xylose yield higher than 40%. The xylanase and the α-l-arabinofuranosidase presented high stability retaining 86.6 and 88.0% of activity after 10 reuse cycles.

Figure optionsDownload as PowerPoint slide