title: Immobilization of Aspergillus niger xylanase on chitosan using dialdehyde starch as a coupling agent.
abstract: Dialdehyde starch (DAS) was used as a novel coupling agent to prepare chitosan carrier to immobilize the xylanase from Aspergillus niger A-25. Compared with glutaraldehyde-cross-linked chitosan (CS-GA) and pure chitosan beads, the DAS-cross-linked chitosan (CS-DAS) beads exhibited the highest xylanase activity recovery. The DAS adding amount and cross-linking time in CS-DAS preparation process were optimized with respect to activity recovery to the values of 1.0 g (6.7% w/v concentration) and 16 h, respectively. The optimum temperature of both the CS-DAS- and CS-GA-immobilized xylanase was observed to be 5 degrees C higher than that of free enzyme (50 degrees C). The CS-DAS-immobilized xylanase had the highest thermal and storage stability as compared to the CS-GA-immobilized and free xylanase. The apparent K (m) and V (max) values of the CS-DAS-immobilized xylanase were estimated to be 1.29 mg/ml and 300.7 mumol/min/mg protein, respectively. The CS-DAS-immobilized xylanase could produce from birchwood xylan high-quality xylo-oligosaccharides, mainly composed of xylotriose, as free xylanase did. The proposed CS-DAS carrier was more advantageous over the CS-GA or pure chitosan carrier for xylanase immobilization application.
authors.affiliation: College of Life Sciences, Henan Agricultural University, Zhengzhou, 450002 Henan, People's Republic of China. honggeyz@163.com
authors.forename: Hongge
authors.initials: H
authors.lastname: Chen
authors.forename: Liangwei
authors.initials: L
authors.lastname: Liu
authors.forename: Shuai
authors.initials: S
authors.lastname: Lv
authors.forename: Xinyu
authors.initials: X
authors.lastname: Liu
authors.forename: Mingdao
authors.initials: M
authors.lastname: Wang
authors.forename: Andong
authors.initials: A
authors.lastname: Song
authors.forename: Xincheng
authors.initials: X
authors.lastname: Jia
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology*; D029662:Betula / Q000737:chemistry; D055162:Biocatalysis; D001672:Biocompatible Materials / Q000737:chemistry; D048271:Chitosan / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000378:metabolism; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D013213:Starch / Q000031:analogs & derivatives* / Q000737:chemistry; D013997:Time Factors; D014990:Xylans / Q000378:metabolism
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D014990:Xylans; D013213:Starch; D048271:Chitosan; C012880:dialdehyde starch; D043364:Endo-1,4-beta Xylanases