Determination of aflatoxin pollution and mycobiota in rainbow trout feed in Alborz province husbandary facilities

Aflatoxins are commonly produced by Aspergillus section Flavi fungi. These fungi can grow and produce toxin in prepared food or ingredients in temperature above 27° c and humidity level more than 16% conditions. The rainbow trout is the most sensitive animal to aflatoxins. The presence of aflatoxins in the rainbow trout's feed may cause decrease in the growth rate, immunosuppression, blood clotting disturbance, liver tumors incidence and several other harmful effects on this fish. In recent study we gathered 20 samples of pelleted rainbow trout's feed from 20 of Alborz province facilities in Autumn and total aflatoxin amounts of samples were measured by direct ELISA assay. The results showed the range of aflatoxin was between 1.34 and 12.4 ppb. The average level of total aflatoxin was reported 4.65 ppb that was less than the standards. Mycobiota of pellet food samples were also evaluated and seven genera (Aspergillus, Mucor, Fusarium, Alternaria, Penicillium, Rhizopus and Absidia) were identified. Aspergillus was the most prevalent genus (46.3%). Among the species of this genus A. flavus with 48.2% and A. fumigatus 5.3% were the most and the least frequent species. The frequency of A. niger was also 34% in 19 samples. In spite of low amount of aflatoxin and regarding to the isolated fungi from the food, there is a risk of fungal toxin production. Thus, storage conditions of food are so important for healthy food.