Depolymerization of Chitosan with a Crude Cellulase Preparation from Aspergillus Niger

Abstract

A crude cellulase preparation from Aspergillus niger was used to depolymerize chitosan. The depolymerization process was followed by measuring the apparent viscocity and the intrinsic viscosity. The optimum conditions for enzymatic hydrolysis were investigated. On the selected optimum conditions (pH 5.0, temperature 50°C, and an enzyme to substrate ratio of 1:5), chitosan was hydrolyzed for 1, 4, 8, and 24 h, its viscosity-average molecular weights were 3.49×10 4 , 1.18×10 4 , 5.83×10 3 , and 1.13×10 3 , respectively. Compared with chitosan having viscosity-average molecular weight of 5.18× 10 5 before enzymatic hydrolysis, the crude cellulase preparation had rather apparent effect on depolymerization of chitosan. Through the comparison of different origin of cellulases, the prepared cellulase has good ability of enzymatic hydrolysis. The reproducibility and reversibility for enzymatic hydrolysis was appraised. The data are of value for the production of low-molecular weight chitosans and chitooligomers of medical and biotechnological interest.

Production of Chitooligosaccharides and Their Potential Applications in Medicine

“…Several authors have employed unspecific enzymes such as papaine and cellulases to degrade chitosans (e.g., [122–124]). Since the enzyme preparations used tend to be rather crude and derived from sources (fungi, plants) that are known to produce chitinolytic enzymes, there remains some doubt concerning which enzymes actually catalyze the hydrolysis reactions.…”

Preparation of chitooligosaccharides by the enzymatic hydrolysis of chitosan

“…Recently, an unspecific hydrolytic action of cellulase on chitosan at optimum condition of pH 4.5 and 60 C was reported [24]. Xie et al described the unspecific hydrolysis of chitosan by a cellulase preparation from Aspergillus niger, which is an alternative economical way of obtaining low molecular weight chitosans and chitooligosaccharides [25]. In this note, we report the preparation and fractionation of chitooligosaccharides, from the trimer to tetradecamer, by the cellulase from A. niger.…”

Improved stability and reusability of endoglucanase from Clostridium thermocellum by a biosilica-based auto-encapsulation method

“…The immobilization of cellulase on various support matrices such as magnetic nanoparticles, silica, polyurethane, and chitosan results in enhanced stability and reusability of cellulase [6][7][8][9]. Moreover, immobilized enzymes can be separated from a solution, thus becoming available for continuous use as a bioreactor, reducing the enzyme sensitivity to external environments, and retaining their catalytic activity.…”