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Applied and Environmental Microbiology, June 2005, p. 3192-3198, Vol. 71, No. 6
0099-2240/05/$08.00+0 doi:10.1128/AEM.71.6.3192-3198.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Hidemi Hatabayashi,1
Hatsue Arai,1
Hiroko K. Kitamoto,2 and
Kimiko Yabe1*
National Food Research Institute, Tsukuba, Ibaraki 305-8642, Japan,1 National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan2
Received 29 September 2004/ Accepted 22 December 2004
The pathway oxoaverantin (OAVN)
averufin (AVR)
hydroxyversicolorone (HVN)
versiconal hemiacetal acetate (VHA) is involved in aflatoxin biosynthesis, and the cypX and moxY genes, which are present in the aflatoxin gene cluster, have been previously suggested to be involved in this pathway. To clarify the function of these two genes in more detail, we disrupted the genes in aflatoxigenic Aspergillus parasiticus NRRL 2999. The cypX-deleted mutant lost aflatoxin productivity and accumulated AVR in the mycelia. Although this mutant converted HVN, versicolorone (VONE), VHA, and versiconol acetate (VOAc) to aflatoxins in feeding experiments, it could not produce aflatoxins from either OAVN or AVR. The moxY-deleted mutant also lost aflatoxin productivity, whereas it newly accumulated HVN and VONE. In feeding experiments, this mutant converted either VHA or VOAc to aflatoxins but did not convert OAVN, AVR, HVN, or VONE to aflatoxins. These results demonstrated that cypX encodes AVR monooxygenase, catalyzing the reaction from AVR to HVN, and moxY encodes HVN monooxygenase, catalyzing a Baeyer-Villiger reaction from HVN to VHA as well as from VONE to VOAc. In this work, we devised a simple and rapid method to extract DNA from many fungi for PCR analyses in which cell disruption with a shaker and phenol extraction were combined.
Present address: Department of Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100094, China.
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