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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.

Flax is an economically important fiber crop, however, it requires degumming to yield usable fibers. The degumming process of flax roving is a key step in flax processing and production. In this study, deep eutectic solvent (DES; choline chloride–urea) pretreatment was combined with microbial treatment to develop an ecofriendly and effective degumming method for flax roving. The optimal conditions for DES pretreatment (100°C for 120 min with 90% DES) were obtained through orthogonal tests. DES combine microbial treatment could effectively remove gum from the flax fibers. The flax roving fibers were characterized by chemical analyses, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometry, and thermogravimetric analysis. Compared with fibers treated with microbes alone, flax roving fibers subjected to DES combine microbial treatment showed better breaking tenacity (16.77 cN/tex) and average pectin, hemicellulose, and lignin removal rates of approximately 86.4%, 26.7%, and 55.1%, respectively. NMR revealed that the composition of DES was not damaged during pretreatment, which means the bulk solution could be reused. This research showed that DES combine microbial treatment is feasible and effective method for flax roving degumming.