Sunday, April 29, 2007

Aspergillus as a microbial cell factory for production of low- and high added value products

Gianni Panagiotou, Susan Meijer, Jens Nielsen, and Lisbeth Olsson. CMB, BioCentrum-DTU, Technical University of Denmark, Building 223, Lyngby, Denmark

Filamentous fungi and fungal products are of remarkable importance to man. The filamentous fungal genus Aspergillus is particularly important because it encompasses diverse species of great relevance within the medical, agricultural and industrial fields. Several species of Aspergilli are of industrial importance, as producers of a wide array of products that range from metabolites, such as organic acids and polyketides, to proteins, both homologous and heterologous. Aspergilli has several properties that make it especially attractive for large scale production of chemicals, including well established fermentation schemes, GRAS status, growth at low pH, high secretion capacity and a broad substrate range, including efficient utilisation of xylose. Furthermore, modern systems biology tools can be used to study Aspergilli allowing efficient metabolic engineering strategies.Xylose is the most abundant pentose sugar in hemicellulose (ca. 25% of dry weight) of hardwoods and crop residues and it is second only to glucose in natural abundance making very attractive its use as a substrate for the production of low- and high added value products. We will present two case studies were different strategies were used to modulate the central carbon metabolism such that carbon from the xylose more efficient can be chanelled to specific products: (1) metabolic engineering strategies for the production of polyketides (2) physiological engineering for improved production of succinate and other organic acids.