Author
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Klich, Maren |
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Submitted to: Culture Collections International Congress
Publication Type: Proceedings Publication Acceptance Date: 6/1/2004 Publication Date: 10/1/2004 Citation: Klich, M.A. 2004. Koji molds and their evil twins, the aflatoxin-producing fungi. In: Proceedings of the Tenth International Congress for Culture Collections, October 10-15, 2004, Tsukuba, Japan. p. 19-23. Interpretive Summary: Technical Abstract: Two of the molds used in koji production, Aspergillus oryzae and A. sojae are very closely related to A. flavus and A. parasiticus, the two economically important fungi that produce the potent carcinogen, aflatoxin, in crop seeds. Ecologically, A. flavus is common and ubiquitous; A. oryzae is less common and ubiquitous; A. parasiticus is found predominantly in soil and agricultural products; and A. sojae is known virtually only from koji production. There is some debate as to whether these four taxa are phylogenetically separate species. Distinguishing A. oryzae from A. flavus and A. sojae from A. parasiticus is difficult but important, especially when developing new strains for commercial use. Morphologically, the koji molds can usually be separated from their toxigenic twins by having larger conidia and brownish colony color in older cultures. A physiological method using an antibiotic medium readily separates A. parasiticus from A. sojae. These fungi have been examined by a number of molecular methods. Some of these methods, including a RFLP method for differentiating A. flavus from A. oryzae and a RAPD method for differentiating A. parasiticus from A. sojae, have proven to be useful in reliably distinguishing these species. |
