Immobilization of xylanase in chitosan-xanthan hydrogels

endo-1,4-beta-Xylanase (E.C. 3.2.1.8) has been immobilized in hydrogel beads prepared by complexation between chitosan and xanthan. The enzyme immobilization efficiency is between 88 and 98% within a wide range of concentrations of xylanase. The optimum xylanase activity requires a pH between 5.0 and 5.5. The immobilized enzymes show 60-70% higher activity than free enzymes. The K-m of the immobilized xylanase increases with the concentration of the enzyme in the beads. The latter show, by electron microscopy, a predominantly fibrilar microstructure within which there are regions having globular shapes where the enzymes are lodged.