Abstract: Using site-directed mutagenesis to mutate the Xanthomonas campestris pectate lyase gene, variants of Xanthomonas campestris pectate lyase with improved thermostability and/or enzymatic activity have been expressed in Escherichia coli, and then isolated and purified. The mutant Xanthomonas campestris pectate lyases are more effective than the wild-type enzyme, also expressed in E. coli, in removing pectic compounds from natural hemp fiber.