Mycoflora, aflatoxigenic strains of Aspergillus section Flavi and aflatoxins in fish feed

Abstract

Commercial feedstuffs are an important component in a modern aquaculture industry. Mycotoxin contamination of fish feeds represents a hazard to aquatic animals and human health. This study aimed to determine the mycoflora, aflatoxigenic strains of Aspergillus section Flavi, and occurrence of aflatoxins in fish feed samples. A total of 86 fish feed samples consisting of pellet, extruder, and scramble samples were collected from feed processing industries and fish farms in Iran. Identification of fungi, in vitro production of aflatoxins by Aspergillus section Flavi strains, and analysis of aflatoxins were done according to standard and established methods. The mean total fungal counts ranged between 2.16 and 4.74 log cfu/g in samples; and 2 samples (2.33%) exceeded the hygienic quality limit, i.e. 4 log cfu/g. Aspergillus was the predominant detected genera followed by Penicillium and Fusarium. Among the Aspergillus species, Aspergillus flavus was the most prevalent species, followed by Aspergillus parasiticus, Aspergillus niger, and Aspergillus ochraceus. All the A. parasiticus isolates and 48.1% of the A. flavus isolates produced aflatoxins in vitro. Contamination with aflatoxins were detected in 58 feed samples (67.5%), ranging between 0.46 and 68.5 ?g/kg. The results revealed that the frequency of contamination with aflatoxins and prevalence of aflatoxigenic fungi in such a level can be a potential hazard for the aquaculture industry and human health. Regular monitoring of mycotoxins specially aflatoxins in feed supply chain can improve the situation through reducing economic losses and minimizing hazards to the public health.