Aflatoxins Investigation and Mycobiota of Selected Marketed Smoked - Dried Fish Samples in Ado-Ekiti, Nigeria and Their Environmental Health Implications

Abstract

Aims: This study was carried out to assess the mycobiota and aflatoxins contamination in selected common smoked-dried fish samples sold at Ojo Oba market in Ado Ekiti, Nigeria and their environmental health implications. Place and Duration of Study: Department of Microbiology, Ekiti State University, Ado Ekiti, Nigeria, between March 2012 and February, 2013. Methodology: Smoked dried fish (Bonga, Cat, Wet African Shad, Butter and Sole) were randomly sampled and purchased from five different marketing sites located at Ojo Oba main market in Ado Ekiti town, Ekiti State, Fifty samples, ten from each related species were analysed. Mycological analysis was done with Potato Dextrose agar using direct plating, washing and dilution methods while the fungi were identified using standard procedure. The moisture content of the fish samples were determined by oven drying at 105ºC for 41/2 h. The aflatoxin extraction, quantitative and qualitative determination was carried out as previously described while the results were analysed using Duncan multiple range test. Results: Eleven different fungal species belonging to six genera were found to be associated with the smoked dried fish samples from the markets sites. The fungal species are Aspergillus niger, A. fumigatus, A. tereus, A. flavus, Absidia sp., Rhizopus sp., Penicillium sp., Penicillium citrinum, Penicillium italicum, Mucorsp and Fusarium moniliformis. Aspergillus flavus and Penicillium sp. had the highest rate of occurrence among the fungi isolated. Aflatoxin B1 and G1 was found in Cat fish (Gymnallabes typhus), West African Shad (Ilisha africana), Sole fish (Cynoglossus browni) while it was not detected in the rest. The aflatoxin B1 and G1 concentration ranged from 2.731 to 4.031 µg.kg-1 and 2.015 to 3.528 µg.kg-1 respectively while the fungal count ranged from 4.7x102 to 9.1x104cfu.g-1. The moisture content ranged from 21.1 to 28.8%. Conclusion: This study showed that smoked dried fish displayed for sale at different market sites in Ojo Oba market in Ado Ekiti, Nigeria were contaminated with species of fungi and aflatoxin which pose a great threat on the health of the consumers. However, fish samples should be well smoked and dried to reduce the moisture content, the samples for sale should be kept in a covered container or show glass to reduce settling of droplets and spores, gloves should be worn by wholesalers and retailers to reduce direct inoculation and storage in a well ventilated environment to reduce contaminations.