Immobilization and Stabilization of Xylanase by Multipoint Covalent Attachment on Agarose and on Chitosan Supports

摘要

Xylanases have important applications in industry. Immobilization and stabilizationof enzymes may allow their reuse in many cycles of the reaction, decreasing the process costs.This work proposes the use of a rational approach to obtain immobilized commercial xylanasebiocatalysts with optimized features. Xylanase NS50014 from Novozymes was characterizedand immobilized on glyoxyl-agarose, agarose-glutaraldehyde, and agarose-amino-epoxysupport and on differently activated chitosan supports: glutaraldehyde-chitosan, glyoxylchitosan,and epoxy-chitosan. Two different chitosan matrices were tested. The best chitosanderivative was epoxy-chitosan-xylanase, which presented 100% of immobilization yield and64% of recovered activity. No significant increase on the thermal stability was observed for allthe chitosan-enzyme derivatives. Immobilization on glyoxyl-agarose showed low yieldimmobilization and stabilization degrees of the obtained derivative. The low concentration oflysine groups in the enzyme molecule could explain these poor results. The protein was thenchemically modified with ethylenediamine and immobilized on glyoxyl-agarose. The newenzyme derivatives were 40-fold more stable than the soluble, aminated, and dialyzed enzyme(70 °C, pH 7), with 100% of immobilization yield. Therefore, the increase of the number ofamine groups in the enzyme surface was confirmed to be a good strategy to improve theproperties of immobilized xylanase.