Secretion of endoxylanase A from Penicillium purpurogenum by Saccharomyces cerevisiae transformed with genomic fungal DNA

Saccharomyces cerevisiae was transformed with a genomic library from Penicillium purpurogenum, and an endoxylanase-producing yeast clone (named 44A) that grows on xylose or xylan as sole carbon source was isolated. This yeast synthesizes xynA mRNA and secretes endoxylanase A to culture media when grown on xylan or xylose, but not glucose. Analysis by pulse-field gel electrophoresis and sequencing indicates that xynA, including its eight introns, has been inserted into the yeast genome. It was shown by sequencing that clone 44A is able to correctly splice xynA introns. This is the first successful attempt to express a fungal endoxylanase gene in yeast with correct intron splicing.