Filamentous fungi as production organisms for glycoproteins of bio-medical interest.

Filamentous fungi are commonly used in the fermentation industry for large scale production of glycoproteins. Several of these proteins can be produced in concentrations up to 20-40 g per litre. The production of heterologous glycoproteins is at least one or two orders of magnitude lower but research is in progress to increase the production levels. In the past years the structure of protein-linked carbohydrates of a number of fungal proteins has been elucidated, showing the presence of oligo-mannosidic and high-mannose chains, sometimes with typical fungal modifications. A start has been made to engineer the glycosylation pathway in filamentous fungi to obtain strains that show a more mammalian-like type of glycosylation. This mini review aims to cover the current knowledge of glycosylation in filamentous fungi, and to show the possibilities to produce glycoproteins with these organisms with a more mammalian-like type of glycosylation for research purposes or pharmaceutical applications.Chemicals/CAS: Glycoproteins; Oligosaccharides; Recombinant Protein

Transformation of Aspergillus niger with the homologous nitrate reductase gene

A homologous transformation for Aspergillus niger was developed based on the nitrate reductase structural gene niaD. This system offered certain advantages over existing A. niger systems, such as the ease of recipient mutant isolation, absence of abortive transformants, convenient enzyme assay, ease of transformant stability testing, and complete absence of background growth. Transformation frequencies of up to 100 transformants per microgram DNA were obtained with the vector pSTA10 which carries the niaD gene of A. niger. Southern blotting analysis indicated that vector DNA had integrated into the genome of A. niger. Mitotic stability studies demonstrated that while some transformants were as stable as the wild-type (wt), others were markedly less so. No correlation was seen between plasmid integration, mitotic stability and nitrate reductase activity, which was markedly different from wt in only three of the transformants examined