Natural occurrence of mycotoxins in Fusarium infected beans.

This is the first report on the discovery of several mycotoxins in naturally infected mouldy navy beans (Phaseolus vulgaris L.) with distinct whitish grey to pink discoloration. Species of Fusarium isolated from the mouldy beans included F. avenaceum, F. culmorum, F. graminearum, F. moniliforme, F. oxysporum, F. solani and two Fusarium spp. Three types of bean samples were analysed for mycotoxins: (a) health beans without any apparent discoloration, (b) beans with pink discoloration, and (c) a mixture of beans with whitish grey and pink discoloration. The results indicated that diacetoxyscripenol (DAS), deoxynivalenol (DON), T-2 toxin (T-2) and fumonisin B1 (FB1) were present in type B and C samples but not in the healthy type A samples. Quantification of DAS, DON, and T-2 and of FB1 were achieved by gas chromatography and high performance liquid chromatography, respectively. The results showed that DAS, DON, T-2 and FB1 were not evident in the healthy samples, but in type B and type C samples, DAS, DON, T-2 and FB1 in the amounts of 9.2, 6.5, 5.5 and 0.5 microgram/g, and of 3.3, 3.1, 13.5 and 1.1 micrograms/g, respectively, were detected. Further research is under way to determine which species of Fusarium is responsible for the production of specific toxins.