Xylanase was immobilized by chitosan and sodium alginate as carrier respectively and the properties of free xylanase and immobilized xylanase were investigated. The results indicated that the Km value of free xylanase was 0.546 mg/L, and the Km values of immobilized xylanase with sodium alginate as carrier and chitosan as carrier were 38 mg/L and 0.342 mg/L respectively. The best pH value for immobilized xylanase with chitosan as carrier and free xylaaase was the same (both as 5.0), but the former one had wider pH range. The optimal pH value ...