ARS | Publication request: Aflatoxin and Ochratoxin Production by Aspergillus Species Under Ex Vivo Conditions

Submitted to: Mycopathologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 21, 2009
Publication Date: June 19, 2009
Citation: Klich, M.A., Tang, S.X., Denning, D.W. 2009. Aflatoxin and Ochratoxin Production by Aspergillus Species Under Ex Vivo Conditions. Mycopathologia.168:185-191.

Interpretive Summary: Many molds produce poisons that are harmful to humans and animals (mycotoxins). A disease caused by members of the mold genus Aspergillus, called aspergillosis, is increasing in frequency and is often fatal in patients with poor immune systems. In this paper we investigate whether or not it would be possible for Aspergillus species growing in humans to form mycotoxins. This is important because toxins could be increasing the virulence of the disease. We grew molds under conditions mimicking those in human bodies. We found that one toxin, aflatoxin, is unlikely to form in human tissue, but that another toxin, ochratoxin, could potentially form in humans with aspergillosis.

Technical Abstract: Aspergillus species are increasingly important human pathogens. It is not known whether toxic metabolites of many of these pathogenic species can act as virulence factors in aspergillosis. We examined isolates of aflatoxin and ochratoxin-producing species for toxin production in ‘near human’ conditions. Seven of the 21 aflatoxin-producing isolates screened produced aflatoxin at 35o and 37o C on the general medium Yeast Extract Sucrose agar (YES). However, none of them produced toxin at these temperatures on Brain Heart Infusion agar (BHA), a medium that mimics human tissue, or on BHA with modified pH or sugar levels. Six of the 12 ochratoxin-producing isolates examined produced toxin at 35o C on YES. All three isolates of A. alliaceus produced ochratoxin on BHA or modified BHA at 37o C. One strain of A pseudoelegans produced a minute amount of ochratoxin on modified BHA at 37o C. These data indicate that aflatoxin is an unlikely virulence factor but that ochratoxin may be a potential virulence factor in aspergillosis.