Gene discovery and expression analysis in aspergillus niger

NSERC Genomics program.

Applicants: Reginald Storms, Adrian Tsang and Greg Butler (Concordia).

The filamentous fungus A. niger is widely used for the industrial production of enzymes and organic acids. We have currently initiated an ESTs program and have so far identified over 1,700 non-redundant genes. We have also constructed cassette-based expression vectors that can be used to express both homologous and heterologous proteins. Some of the expression vectors carry reporter genes that can be used to screen for mutant strains that express proteins at higher levels. It is estimated that the A. niger genome with a size of about 30 Mb codes for at least 8,000 genes.

We plan to construct a normalized cDNA library and expand our EST program to identify over 80% of the expressed genes. Once cDNA clones representing the expressed gene set have been identified, they will be used to construct DNA microarrays. These arrays will then be used to measure global gene expression in wild type and mutant strains under different growth conditions. The proposed EST program will identify genes that have industrial and environmental applications as well as undesirable ones. Of particular interest to us are those coding for enzymes involved in the breakdown of complex sugars, lignin and environmental toxins.

Analysis of the results from transcriptional profiling will enhance our understanding about how protein expression and protein secretion are regulated. Moreover, the EST results and transcriptional profiling database will identify proteins with commercial relevance and facilitate rational approaches for engineering expression strains that can express and secrete valuable proteins at the high levels required by industry.