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Depolymerization of chitosan with a crude cellulase preparation from Aspergillus niger
1College of Environment and Chemical Engineering, Nanchang Hangkong University, No.696 Fenghe Southern Road, Nanchang, Jiangxi 330063, People's Republic of China. xieyu_121@163.com.
Applied Biochemistry and Biotechnology
|April 1, 2009
Summary
Enzymatic hydrolysis using Aspergillus niger cellulase effectively depolymerizes chitosan into low-molecular-weight forms. This process yields valuable chitosans and chitooligomers for medical and biotechnological applications.
Area of Science:
- Biochemistry
- Biotechnology
- Materials Science
Background:
- Chitosan, a biopolymer derived from chitin, possesses valuable properties but its high molecular weight limits certain applications.
- Enzymatic depolymerization offers a controlled method for modifying chitosan's molecular weight and properties.
- Cellulases, particularly from microbial sources like Aspergillus niger, are explored for their potential in biopolymer modification.
Purpose of the Study:
- To investigate the enzymatic depolymerization of chitosan using a crude cellulase preparation from Aspergillus niger.
- To determine the optimal conditions for chitosan hydrolysis by cellulase.
- To evaluate the molecular weight reduction and potential applications of the resulting low-molecular-weight chitosans and chitooligomers.
Main Methods:
- Chitosan depolymerization was performed using a crude cellulase preparation from Aspergillus niger.
- The depolymerization process was monitored by measuring apparent and intrinsic viscosity.
- Optimal hydrolysis conditions (pH 5.0, 50°C, enzyme-to-substrate ratio 1:5) were identified and applied for timed hydrolysis (1-24 hours).
Main Results:
- Enzymatic hydrolysis significantly reduced chitosan's viscosity-average molecular weight from 5.18 x 10^5 to as low as 1.13 x 10^3 after 24 hours.
- Optimal conditions yielded effective depolymerization, demonstrating the cellulase preparation's capability.
- The study confirmed the reproducibility and reversibility of the enzymatic hydrolysis process.
Conclusions:
- Crude cellulase from Aspergillus niger is effective for producing low-molecular-weight chitosans and chitooligomers.
- The optimized enzymatic hydrolysis process provides a viable route for generating chitosan derivatives with tailored molecular weights.
- The resulting low-molecular-weight chitosans and chitooligomers hold significant potential for medical and biotechnological applications.
