Characterization of polygalacturonase-overproducing Aspergillus niger transformants

• Published in: Applied microbiology and biotechnology Vol. 37; no. 3; pp. 324 - 329
• Main Authors: Bussink, H.J.D, Hombergh, J.P.T.W. van den, Ijssel, P.R.L.A. van den, Visser, J
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01-06-1992
• Subjects: Aspergillus niger; Biological and medical sciences; enzyme activity; Fundamental and applied biological sciences. Psychology; Laboratorium voor Erfelijkheidsleer; Laboratory of Genetics; Microbiology; Mycology; polygalacturonase; proteins; Characterization; Fungi; Regulation(control); Transformation; Enzyme; Production; Gene organization; Polygalacturonase; Gene expression; Thallophyta
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/BF00210987

Aspergillus niger pyrA co-transformants with multiple copies of the gene (pgaII) encoding the major endopolygalacturonase were characterized in detail. Typically, these transformants produced tenfold or more polygalacturonase from plasmids that had integrated in most cases at ectopic sites, in comparison to the untransformed strain. Some mitotic instability was observed upon application of a positive selection procedure for reversion of the pyrA marker. Analysis of these strains indicated that the most frequent event involved is the excision of part of the array of tandemly integrated plasmids, without "scrambling" of the plasmids remaining in the chromosome. From promoter deletion analysis it was concluded that the pgaII gene is subject to positive control. The putative positive regulatory protein appears not to be limiting for overexpression of the pgaII gene.