Characterization of a novel xylanase from Armillaria gemina and its immobilization onto SiO sub(2) nanoparticles

• Published in: Applied microbiology and biotechnology 2013-02, Vol.97 (3), p.1081-1091
• Main Authors: Dhiman, Saurabh Sudha, Kalyani, Dayanand, Jagtap, Sujit Sadashiv, Haw, Jung-Rim, Kang, Yun Chan, Lee, Jung-Kul
• Format: Article
• Language: English
• Subjects: Armillaria; Catalysts; Endoglucanase; Enzymes; Fungi; Immobilization; Nanoparticles; Silicon oxides; Xylanase
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-012-4381-9

Enhanced catalytic activities of different lignocellulases were obtained from Armillaria gemina under statistically optimized parameters using a jar fermenter. This strain showed maximum xylanase, endoglucanase, cellobiohydrolase, and beta -glucosidase activities of 1,270, 146, 34, and 15 U mL super(-1), respectively. Purified A. gemina xylanase (AgXyl) has the highest catalytic efficiency (k sub(cat)/K sub(m)=1,440 mgmL super(-1)s super(-1)) ever reported for any fungal xylanase, highlighting the significance of the current study. We covalently immobilized the crude xylanase preparation onto functionalized silicon oxide nanoparticles, achieving 117 % immobilization efficiency. Further immobilization caused a shift in the optimal pH and temperature, along with a fourfold improvement in the half-life of crude AgXyl. Immobilized AgXyl gave 37.8 % higher production of xylooligosaccharides compared to free enzyme. After 17 cycles, the immobilized enzyme retained 92 % of the original activity, demonstrating its potential for the synthesis of xylooligosaccharides in industrial applications.