Thongpoo Preeyanuch, Srisomsap Chantragan, Chokchaichamnankit Daranee, Kitpreechavanich Vichien, Svasti Jisnuson, Kongsaeree Prachumporn T
a Interdisciplinary Graduate Program in Genetic Engineering, Faculty of Graduate School , Kasetsart University , Bangkok , Thailand.
Biosci Biotechnol Biochem. 2014;78(7):1167-76. doi: 10.1080/09168451.2014.915727. Epub 2014 May 28.
Production and utilization of cellulosic ethanol has been limited, partly due to the difficulty in degradation of cellulosic feedstock. β-Glucosidases convert cellobiose to glucose in the final step of cellulose degradation, but they are inhibited by high concentrations of glucose. Thus, in this study, we have screened, isolated, and characterized three β-glycosidases exhibiting highly glucose-tolerant property from Aspergillus niger ASKU28, namely β-xylosidase (P1.1), β-glucosidase (P1.2), and glucan 1,3-β-glucosidase (P2). Results from kinetic analysis, inhibition study, and hydrolysis of oligosaccharide substrates supported the identification of these enzymes by both LC/MS/MS analysis and nucleotide sequences. Moreover, the highly efficient P1.2 performed better than the commercial β-glucosidase preparation in cellulose saccharification, suggesting its potential applications in the cellulosic ethanol industry. These results shed light on the nature of highly glucose-tolerant β-glucosidase activities in A. niger, whose kinetic properties and identities have not been completely determined in any prior investigations.
纤维素乙醇的生产和利用一直受到限制，部分原因是纤维素原料难以降解。β-葡萄糖苷酶在纤维素降解的最后一步将纤维二糖转化为葡萄糖，但它们会受到高浓度葡萄糖的抑制。因此，在本研究中，我们从黑曲霉ASKU28中筛选、分离并鉴定了三种具有高度葡萄糖耐受性的β-糖苷酶，即β-木糖苷酶（P1.1）、β-葡萄糖苷酶（P1.2）和葡聚糖1,3-β-葡萄糖苷酶（P2）。动力学分析、抑制研究以及寡糖底物水解的结果通过液相色谱/串联质谱分析和核苷酸序列支持了这些酶的鉴定。此外，高效的P1.2在纤维素糖化过程中表现优于商业β-葡萄糖苷酶制剂，表明其在纤维素乙醇工业中的潜在应用。这些结果揭示了黑曲霉中高度葡萄糖耐受性β-葡萄糖苷酶活性的本质，其动力学性质和身份在以往的任何研究中都尚未完全确定。
