Evaluation of the catalase promoter for expressing the alkaline xylanase gene (alx) in Aspergillus niger


Correspondence: Meenu Katoch, Department of Biotechnology, Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu-180001, India. Tel.: +91 09419157224; fax: +91 01912 569017; e-mail: meenusamiksha@rediffmail.com


Aspergillus niger represents a promising host for the expression of recombinant proteins, but only a few expression systems are available for this organism. In this study, the inducible catalase promoter (PcatR) from A. niger was characterized. For this, constructs were developed and checked for the expression of the alkaline xylanase gene transcriptionally fused under the cat R promoter. Two versions of the catalase (catR) promoter sequence from A. niger (Pcat300,Pcat924) were isolated and tested for their ability to drive expression of the alkaline xylanase (alx) gene. Pcat924 showed better efficiency (more than 10-fold increase in AlX activity compared to Pcat300) under the optimized culture conditions. Induction of the catR promoter with 0.20% H2O2 and 1.5% CaCO3 in the culture medium, further increased expression of AlX 2.61- and 2.20-fold, respectively, clarifying its inducible nature. Specific induction or repression of the catR promoter provides the possibility for utilization of this promoter in heterologous protein production.