Co-Authors:
Lisker, N., Department of Agronomy and Natural Resources Agricultural Research Organization, The Volcani Center, Bet Dagan, 50250, Israel
Zhang, G.S., Food Research Institute and Department of Food Microbiology and Toxicology, University of Wisconsin, Madison, 53706, WI, United States
Chu, F.S., Food Research Institute and Department of Food Microbiology and Toxicology, University of Wisconsin, Madison, 53706, WI, United States
Abstract:
Aflatoxin G 1 (AFG 1) was transformed into aflatoxin B 3 (AFB 3) by the fungi Rhodotorula sp, Sporobolomyces sp, Rhizopus oryzae NRRL395, Pythium ultimum, Aspergillus terreus, A clavatus and Penicillium frequentans grown in a medium containing AFG 1, Difco potato dextrose broth, yeast extract, and peptone both in liquid shaken cultures and in solid static cultures at 25°C in the dark. A maximum rate of transformation of 10 % was obtained after 2 to 3 weeks of incubation. The transformation was correlated with an increase in the pH of the media from 5.7 -5.9 to 8.3 - 8.8. Saccharomyces cerevisiae also transformed AFG 1 into AFB 3, but at a slower rate; the pH of the media did not reach above 8.0 until 5 weeks after incubation. No transformation was observed when A niger and P chrysogenum were tested; in both cases, no increase in pH was noticed. However, some transformation of AFG 1 to AFB 3 by both fungi was observed when the initial pH of the media was adjusted to 9.0. The rate of transformation increased to 15 - 20% in the static culture where the same medium was adsorbed onto vermiculite and Rhizopus and Aspergilli gave the highest increase in AFB 3 yield. © 1990 Society of Mycotoxin Research and Springer.