The saprophytic fungus Aspergillus niger is an efficient producer of extracellular enzymes. Previous research has revealed that many of these enzymes show carbohydrate modifying activities. These enzymes are Generally Regarded As Safe (GRAS status) and are therefore widely used in the food industry. Recently DSM Food Specialties solved the genomic sequence of this fungus. Based on the new data, it was estimated that only a fraction of the potential of enzymes secreted by A. niger is currently characterized. D atabase mining using the proprietary genome sequence has resulted in the identification of at least total thirty-eight genes encoding enzymes involved in the depolymerisation of the backbone of the complex polysaccharide pectin. Additional enzymatic activities are required to degrade the arabinogalactan side chains attached to the main chain and to remove methyl and acetyl esters that are present in this main chain. By applying the powerful technology of DNA microarrays we have sought to gain insight into the complex regulation of the expression of all the genes involved in pectin degradation. For this we have cultivated A. niger on sugar beet pectin and on the monomeric sugar constituents of pectin, viz galacturonic acid, rhamnose and xylose, and subsequently analysed the corresponding transcriptomes using microarrays. W e will report on our findings concerning the regulation of the expression of the genes involved in the degradation of pectin and the consequences for the interplay of the encoded (novel) enzymes.
Full conference title:
23rd Fungal Genetics Conference
- Fungal Genetics Conference 23rd (2002)