AN EXPRESSION SYSTEM BASED ON THE PROMOTER REGION OF THE ASPERGILLUS-AWAMORI 1,4-BETA-ENDOXYLANASE A GENE

A new, highly inducible fungal promoter derived from the Aspergillus a wamori 1,4-beta-endoxylanase A (exlA) gene is described. Induction ana lysis, carried out with the wild-type strain in shake flasks, showed t hat exlA expression is regulated at the transcriptional level. Using a beta-glucuronidase (uidA) reporter strategy, D-xylose was shown to be an efficient inducer of the exlA promoter, whereas sucrose or maltode xtrin were not. Upon D-xylose induction, the exlA promoter was threefo ld more efficient than the frequently used A. niger glucoamylase (glaA ) promoter under maltodextrin induction. Detailed induction analyses d emonstrated that induction was dependent on the presence of D-xylose i n the medium. Carbon-source-limited chemostat cultures with the uidA r eporter strain showed that D-xylose was also a very good inducer in a fermenter, even in the presence of sucrose.