Central Institute of Post-Harvest Engineering and Technology, P.O. PAU, Ludhiana, 141 004, India,
Antonie Van Leeuwenhoek. 2014 Jan;105(1):119-34. doi: 10.1007/s10482-013-0060-9. Epub 2013 Oct 25.
Fungi isolated from partially decayed wood log samples showing characteristic diversity for spore colour, colony morphology and arrangement of spores were assessed for cellulolytic enzyme production. Isolates showing a cellulolytic index of ≥2.0 were assayed for filter paper (FP) cellulase and β-glucosidase (BGL) production. Molecular characterization confirmed the identity of the selected cellulolytic isolate as a strain of Aspergillus niger (A. niger HN-2). Addition of 2 % (w/v) urea enhanced FP and BGL activity by about 20 and 60 %, respectively. Validation studies conducted at parameters (29 °C, pH 5.4, moisture content 72 % and 66 h) optimized through response surface methodology in a solid-state static tray fermentation resulted in FP, BGL, cellobiohydrolase I (CBHI), endoglucanase (EG), xylanase activity and protein content of 25.3 FPU/g ds, 750 IU/g ds, 13.2 IU/g ds, 190 IU/g ds, 2890 IU/g ds and 0.9 mg/ml, respectively. In comparison, A. niger N402 which is a model organism for growth and development studies, produced significantly lower FP, BGL, CBHI, EG, xylanase activity and protein content of 10.0 FPU/g ds, 100 IU/g ds, 2.3 IU/g ds, 50 IU/g ds, 500 IU/g ds and 0.75 mg/ml, respectively under the same process conditions as were used for A. niger HN-2. Process optimization led to nearly 1.8- and 2.2-fold increase in FP and BGL activity, respectively showing promise for cellulase production by A. niger HN-2 at a higher scale of operation. Zymogram analysis revealed two isoforms each for EG and cellobiohydrolase and three isoforms for BGL. Crude cellulase complex produced by A. niger HN-2 exhibited thermostability under acidic conditions showing potential for use in biofuel industry.
从部分腐烂的原木样本中分离出的真菌，其孢子颜色、菌落形态和孢子排列具有特征性的多样性，这些真菌被评估用于纤维素酶的生产。表现出纤维素指数≥2.0 的分离物被用于滤纸（FP）纤维素酶和β-葡萄糖苷酶（BGL）的生产。分子鉴定证实，所选纤维素分解菌是黑曲霉（A. niger HN-2）的一个菌株。添加 2%（w/v）尿素分别使 FP 和 BGL 活性提高约 20%和 60%。通过响应面法在固态静态托盘发酵中优化参数（29°C、pH5.4、水分含量 72%和 66 小时）进行的验证研究，导致 FP、BGL、纤维二糖水解酶 I（CBHI）、内切葡聚糖酶（EG）、木聚糖酶活性和蛋白含量分别为 25.3 FPU/g ds、750 IU/g ds、13.2 IU/g ds、190 IU/g ds、2890 IU/g ds 和 0.9 mg/ml。相比之下，黑曲霉 N402 是用于生长和发育研究的模型生物，在相同的工艺条件下，其 FP、BGL、CBHI、EG、木聚糖酶活性和蛋白含量分别显著较低，为 10.0 FPU/g ds、100 IU/g ds、2.3 IU/g ds、50 IU/g ds、500 IU/g ds 和 0.75 mg/ml。在相同的工艺条件下，黑曲霉 HN-2 的 FP 和 BGL 活性分别提高了近 1.8 倍和 2.2 倍，表明黑曲霉 HN-2 有望在更高的操作规模下生产纤维素酶。酶谱分析显示 EG 和纤维二糖水解酶各有两个同工酶，BGL 有三个同工酶。黑曲霉 HN-2 产生的粗纤维素酶复合物在酸性条件下表现出热稳定性，有望在生物燃料工业中得到应用。
