PRODUCTION OF A BACTERIAL THERMOPHILIC XYLANASE IN SACCHAROMYCES-CEREVISIAE

The xynA gene (encoding xylanase) from the obligately anaerobic thermo philic bacterium Caldocellum saccharolyticum has been inserted into th e yeast expression vector, pFLAGU2. Yeast cells containing this vector were able to produce and secrete active xylanase into the growth medi um. Xylanase was purified by the use of an affinity column specific fo r a rare peptide sequence fused to the N-terminus of the xylanase. Sod ium dodecyl sulphate-polyacrylamide gel electrophoresis of the purifie d fractions revealed that the enzyme had been fortuitously glycosylate d. The specific activity of the purified xylanase was found to be 90 i nternational units/mg protein. The amount of xylanase secreted into th e surrounding medium was approximately 10 mg/l.