Production of Aspergillus terreus xylanase in solid-state cultures: application of the Plackett–Burman experimental design to evaluate nutritional requirements

详细信息	查看全文 | 推荐本文 |

• 作者：Ghanem ; Nevine B. ; Yusef ; Hoda H. ; Mahrouse ; Heba K.
• 关键词：Aspergillus terreus ; Xylanase ; Solid-state fermentation ; Wheat straw
• 刊名：Bioresource Technology
• 出版年：2000
• 期刊代码：11_09608524
• 类别：ce
• 出版时间：June, 2000
• 卷：73
• 期：2
• 页码：113-121
• 文件大小：602 K

摘要

Xylanase was produced by Aspergillus terreus cultivated on finely ground wheat straw in solid-state fermentation. The optimal medium composition was developed by applying the Plackett–Burman experimental design. Best enzymic activity was obtained in a medium containing 10 g wheat straw/flask moistened with a concentrated nutrient salt solution to 75%initial water content and incubated for 4 days at 30°C. A. terreus xylanase was fractionated by ammonium sulfate precipitation and purified by chromatography on DEAE Bio-Gel A followed by gel-filtration on Sephadex G-75. The enzyme was characterized by apparent V_max and K_m values of 333.3 U/mg protein and 16.7 mg xylan/ml, respectively, obtained for xylanase with oat spelt xylan as substrate. The optimal pH and temperature for maximum activity were 7 and 50°C, respectively. The enzyme showed high specificity towards oat spelt xylan and minute activities were observed with carboxymethyl cellulose and cellobiose. About 48.02%of the activity remained after the enzyme had been incubated at 60°C for 30 min. Metal ions such as Hg²⁺, Cu²⁺, Co²⁺, Fe³⁺, Pb²⁺ strongly inhibited xylanase, whereas, Ca²⁺ activated the enzyme.