1968 Volume 9 Issue 1 Pages 29-34
Fungal isolates from rice and flours were tested to determine if aflatoxin producing fungi are present in Japan. One hundred and fifteen strains, including 21 strains of the Aspergillus flavus group, were tested. Fifty one of 115 strains were isolated from rice samples and the others from several kinds of flours including wheat, red bean, and soybean. The isolates were selected from a total of 1300 on the basis of frequency of isolation of species except that all Aspergillus flavus isolates were tested. In primary screening tests, the cultures were grown in shake culture for 96 hours in modified Czapek liquid medium. The presence of aflatoxins were determined by thin-layer chromatography of chloroform extract of the broth. Eleven isolates including 5 belonging to the Aspergillus flavusgroup appeared to produce aflatoxin B1 alone or B1 and B2. Further large scale tests indicated that strains of Aspergillus flavus produced compounds which showed the same thin layer chromatographic behaviours as authentic aflatoxin B1. Production of aflatoxin B1 was confirmed by the trifluoroacetylation procedure of Andrellos and Reids (1964), and by measurement of ultraviolet and infrared spectra. Oral administration to rats of extract of one strain of Aspergillus flavus (WF-3-8) caused histopathological change to the livers accompanied with bile duct hyperplasia similar to that observed in the liver of rats fed toxic peanut meal.
This is the first report of aflatoxin producing fungi isolated from foodstuffs in Japan. No aflatoxin producing strains were found among those isolated from rice samples.
