Submitted to: Encyclopedia of Food Microbiology
Publication Type: Book / Chapter
Publication Acceptance Date: June 5, 1999
Publication Date: N/A
Interpretive Summary: Not applicable.
Technical Abstract: Filamentous fungal species in Aspergillus Section Flavi, more commonly known as the "Aspergillus flavus group," are of great economic importance. Several species, including Aspergillus flavus, not only cause food spoilage, but also produce potent toxins and are pathogenic to humans and animals. Whereas, other species such as A. oryzae and A. sojae are used in nfood fermentations. Undoubtedly, the most important fungi in this group are the aflatoxigenic molds, A. flavus and A. parasiticus, and the relatively recently described but much less frequently reported species, A. nomius, because these species occur worldwide and cause preharvest aflatoxin contamination in corn, peanuts, cottonseed and treenuts. These seed-inhabiting fungi also contaminate a wide variety of crops after harvest, during handling and during processing. Fungi of this group lack a sexual stage of development, and propagate vegetatively through asexual spores (conidiospores or conidia) or vegetative cells (filamentous mycelia). The three aflatoxigenic species are closely related and have many similarities but, among other characteristics, they can be distinguished based on the toxins produced by them. Aspergillus flavus can produce aflatoxins B1 and B2, and cyclopiazonic acid, but only about half of the natural isolates are toxigenic. Aspergillus parasiticus produces aflatoxins G1, G2, in addition to B1 and B2, but not cyclopiazonic acid, and almost all of the isolates are toxigenic. Aspergillus nominus is morphologically similar to A. flavus but, like A. parasiticus, produces B and G aflatoxins without producing cyclopiazonic acid.