Production of xylanase by Aspergillus niger NCH-3 with coba husk hemicellulose ( in stirred tank ) and its application on the preparation of the xylooligoaccharides

• Main Authors: Tseng Shih-Hao, 曾士豪
• Other Authors: Chin-Shuh Chen﹐Ph.D.
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/32608373258569200693

碩士 === 國立中興大學 === 食品科學系 === 90 === The xylanase production from a fungal isolate, Aspergillus niger NCH-3, by using the hemicellulose extracting from a domestic agricultural waste coba husk as carbon source was studied. These included determinations of optimal condition for extracting from hemicellulose, and the medium composition for optimal xylanase production, characterization of enzyme properties, and the hydrolysis profiles of xylanase using coba husk hemicellulose and/or oat spelt xylan as enzymatic substrates. The optimal conditions for extracting hemicellulose from coba husk by NaOH were that using 15% NaOH at 60℃for 5 hr or that at 40℃for 30hr. The yields were about 23.7 and 24.0%, respectively；however, the highest yield, 25.2%, was obtained at 60℃for 30 hr. The better medium composition for Aspergillus niger NCH-3 xylanase production were determined by using a 5 L bench-top fermentor as follows：coba husk hemicellulose, 1.0 %；corn steep liquor, 1.0 %；KNO3, 0.38 %；KH2PO4, 0.02 %；CaCl2, 0.0002 %；Tween 80, 0.2 %；MgSO4．7H2O, 0.03 %；FeSO4． 7H2O, 0.0005 %； ZnSO4． 7H2O, 0.0014 %；MnSO4．H2O, 0.00016 %, pH 8.0. The strain was cultivated at 35℃, with agitation rate at 150 rpm, and aerated at 1.0 vvm for 5 days. The final xylanase activity obtained was at 32.4 U/ml. The optimal pH for the UF and ammonium sulfate precipitation -purified xylanase was pH 5.0, however, the enzyme remained stable at pH ranging values from pH 4.0 to 7.0. Both thermal stability and optimal temperature for partially purified xylanase were at 50℃. The enzyme also showed high specificity on xylans composed of xylose residues. The types of major hydrolysis products of either coba husk hemicellulose or oat spelt xylan catalyzed by the UF- or UF-ammonium sulfate precipitation-purified xylanase after 24 hours depended upon the ratio of substrate to the amount of enzyme used；however, xylose and xylobiose were the major ones.