黄曲霉群菌种产生黄曲霉毒素B_1的调查研究

本文对来自我国20个省、市、自治区的不同基物上分离的和中国科学院微生物研究所菌种保藏室以及其他单位提供的黄曲霉群菌种,经随机选取82株进行了黄曲霉毒素B_1的测定,证明在测试的9个已知分类群中产生黄曲霉毒素B_1的菌种只限于寄生曲霉和黄曲霉,另外4株种名未定者也能产生此种毒素。在黄曲霉中产毒菌株约占30％(28.3％),其在GAN(葡萄糖硝酸铵)和大米培养基中的黄曲霉毒素B_1的最高产量分别为133,333.3和160,000.0ppb。总的来说,大体上可以反映在我国一般基物上黄曲霉产毒菌株存在的现状。在实验过程中,还对黄曲霉群菌种在GAN和大米培养基中黄曲霉毒素B_1的产量和产毒菌株数作了比较。发现在大米培养基中黄曲霉毒素B_1的产量高于GAN,而且测试的黄曲霉产毒菌株在这两种培养基中均各有不能产毒的菌株,因此,在测定产毒菌株时,若仅采用其中一种产毒培养基,往往会有漏掉产毒菌株的可能性。

INVESTIGATION ON AFLATOXIN B_1 PRODUCING SPECIES OF ASPERGILLUS FLAVUS GROUP

In this paper, Aflatoxin B_1-producing ability of the randomly selected 82 strains of Aspergillus flavus group (including 9 taxa anl 2 unknown species) was assayed. The strains were isolated from various substrates from different localities in China, and supplied by Laboratory of Culture Collection of the Institute of Microbiology, the Chinese Acadefy of Sciences and other organizations. It has been proved that Aflatoxin B_1 is produced only by the strains of A. parasiticus and A. flavus among the 9 taxa known, and 2 unknown species are also Aflatoxin B_1 producers. Within the strains of A. flavus tested, the positive rate of Aflatoxin B_1 producers approximate to 30% (28.3%). The highest amount of Aflatoxin B_1 produced in GAN (Glucose Ammonium Nitrate) anl rice media are 133,333.3 and 160,000.0 ppb respectively, roughly reflecting the present situation of Aflatoxin B_1 producers growth on general substrates in China. In the course of the experiment, the yield of Aflatoxin B_1 and the number of Aliatoxin B_1 producers of A. flavus group in GAN and rice media are also compared. As a result, the yield of Aflatoxin B_1 produced in rice is higher than that in GAN. Within the Aflatoxin B_1 producers of A. flavus (15 strains), some of the strains tested were found to be Aflatoxin B_1 negative in GAN or rice medium. However, Aflatoxin B_1 was found to be positive in one of them. Apparently, Aflatoxin B_1 producers would be missed if only one of the two media is used.