Aspergillus niger is a member of the black aspergilli (Aspergillus sect. Nigri) and is a common food spoilage fungus. A. niger holds GRAS (Generally Regarded As Safe) status and is widely used in the food industry as a source of hydrolytic enzymes and organic acids. However, some strains of A. niger are able to produce the nephrotoxin, ochratoxin A (OTA), and have been associated with OTA in coffee and grape products. Despite its importance, the taxonomy of A. niger, and other members of the black aspergilli, remains unclear. Species identification is primarily based on morphological criteria, but a growing number of molecular techniques are being applied to the A. niger aggregate. RFLP analyses have divided the A. niger aggregate into types N and T, and RAPD analyses have shown a high level of intraspecific variability. The molecular techniques, Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR, Amplified Fragment Length Polymorphisms (AFLP) and microsatellite markers were evaluated for their suitability in typing strains of A. niger. Strains assessed included isolates from culture collections and those isolated from natural substrates including grapes, coffee, animal feed and soil. The collection included both toxigenic and nontoxigenic isolates. ERIC-PCR differentiated A. niger from other closely related black aspergilli. AFLP analysis separated A. niger strains into types N and T, and this was confirmed by analysis using six novel microsatellite markers, developed for A. niger. Furthermore, both the AFLP and microsatellite analyses separated type N strains into two distinct groups. No correlation was seen between toxin production and genotype.
Full conference title:
23rd Fungal Genetics Conference
- Fungal Genetics Conference 23rd (2002)