RESUMO
The xylanase gene of Bacillus subtilis B10 which had an excellent capacity for degumming ramie fibres was cloned by PCR amplification. The xylanase gene was cloned into vector pBluescript II KS+ and the CaMV 35S promoter was inserted in front of the gene, and the expression vector pKS-35SXYHyg was constructed successfully after the Hyg~(r) gene was inserted into the multi-cloning sites of pBluescript II KS+. The expression vector was linearized and transformed protoplasts of Aspergillus niger strain An1. Hygromycin-resistant transformants were generated and the integration of xylanase gene was confirmed by genomic Southern blotting analysis. Compared with An1, the xylanase activity of the transformant AT1 was increased more than trebled, and the residual gum content was decreased by 55.18% after the ramie was treated by culture supernatants from AT1.