A Novel endo-β-1,4-xylanase xyl-1 from Aspergillus terreus HG-52 for High-Efficiency Ramie Degumming

ABSTRACT

Xylanase is the key enzyme responsible for the degradation of hemicellulose and plays an important role in ramie degumming. In this study, an endo-β-1,4-xylanase xyl-1 of GH11 family from Aspergillus terreus HG-52 was cloned and identified for the first time. The protein was heterologously expressed in Escherichia coli BL21, then purified and analyzed for its biochemical properties. The optimal temperature and pH of xyl-1 are 45°C and pH 5, respectively, with a specific activity as high as 1505.11 U/mg. The immunofluorescence staining combined in-situ catalysis of ramie slices revealed that xyl-1 could degrade ramie xylan fraction. The scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy analysis of ramie fibers treated by xyl-1 showed that the treated fibers were more dispersed, the crystallinity was improved, the absorption peak of hemicellulose functional group was reduced. Residual hemicellulose content reduced from 14.93% to 5.75% and whiteness was reached 45.4, indicating xyl-1 had high-efficiency degumming ability for ramie hemicellulose. This work excavated a promising endo-β-1,4-xylanase for ramie fibers degumming applications and has good potential for commercial application.

摘要

木聚糖酶是半纤维素降解的关键酶，在苎麻脱胶中起着重要作用. 本研究首次克隆并鉴定了土曲霉HG-52中GH11家族的内切-β-1,4-木聚糖酶xyl-1. 该蛋白在大肠杆菌BL21中异源表达，然后纯化并分析其生化特性. xyl-1的最适温度和pH分别为45°C和5，比活性高达1505.11 U/mg. 免疫荧光染色结合苎麻切片的原位催化显示xyl-1可以降解苎麻木聚糖组分. 经xyl-1处理的苎麻纤维的扫描电镜、X射线衍射和傅里叶变换红外光谱分析表明，处理后的纤维更加分散，结晶度提高，半纤维素官能团的吸收峰降低. 剩余半纤维素含量从14.93%降至5.75%，白度达到45.4，表明xyl-1对苎麻半纤维素具有高效脱胶能力. 这项工作为苎麻纤维脱胶应用开发了一种有前途的内切-β-1,4-木聚糖酶，具有良好的商业应用潜力.

KEYWORDS:

• Aspergillus terreus
• endo-β-1,4-xylanase
• immunofluorescence
• ramie degumming
• hemicellulose
• high-efficiency

关键词:

• 土曲霉
• 内切-β-1,4-木聚糖酶
• 免疫荧光
• 苎麻脱胶
• 半纤维素
• 高效率

Acknowledgments

Protein fragmentation and purification were carried out at the Research Core Facilities for Life Science (HUST). The SEM, XRD and ATR-FTIR analysis were conducted in Analytical and Testing Center of Huazhong University of Science and Technology.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was financially supported by the National Natural Science Foundation of China (No. 21676111)、Major Programs of Technical Innovation of Hubei Province (No. 2019AAA033) and the Graduates’ Innovation Fund, HUST (YCJJ202203016).