Effects of volatile aldehydes from Aspergillus-resistant varieties of cornon Aspergillus parasiticus growth and aflatoxin biosynthesis

The fungi Aspergillus flavus and Aspergillus parasiticus produce a potent c lass of hepatocarcinogens known as aflatoxins. Corn-derived volatile compou nds have been previously found to affect growth and aflatoxin production in A. flavus. In this study, the effects on A. parasiticus of three corn-deri ved volatile compounds, n-decyl aldehyde, hexanal and octanal, were measure d. These three compounds were previously found to be variably expressed in five Aspergillus-resistant maize strains and three susceptible strains. In this study, A. parasiticus radial growth was restricted least by n-decyl al dehyde and most by octanal. Treatments of 100 mu l of both hexanal and octa nal were found to completely inhibit radial growth of the fungus using an a gar plate assay method. While the volatile compound n-decyl aldehyde had le ss of an effect on radial growth than the other volatiles, the n-decyl alde hyde treated colonies had a predominance of uniquely aerial hyphae. These c olony structures were found to have more complex hyphae and significantly f ewer conidiophores than the control and other aldehyde treatments. Furtherm ore, aflatoxin production by the fungus was reduced by n-decyl aldehyde and hexanal, but was stimulated by octanal. The results presented here indicat e that all three volatile compounds reduce radial growth but only n-decyl a ldehyde significantly inhibits aflatoxin biosynthesis in A. parasiticus. Pu blished by Elsevier Science Ltd.