Molecular detection of aflatoxigenic mould contaminants isolated from fragmented stockfish (Gadus morhua) retailed in Sango-Ota Markets, Ogun State, Nigeria

Abstract

The occurrence of aflatoxigenic moulds in fragmented stockfish (Gadus morhua), popularly known in Nigeria as Okporoko, retailed in  some selected markets in Ota, Ogun State, was investigated and the isolated moulds were molecularly identified. A total of 45 (15 each of  Head, H; Trunk, Tr and Tail, Tl) samples randomly procured from three selected markets were analyzed for total mould count following standard procedures. The isolates were grown on Yeast Extract Sucrose (YES) agar and exposed to Ammonium hydroxide to evaluate the  phenotypic aflatoxigenicity. Molecular detection of Aflatoxins genes was carried out using the universal primer for moulds (ITS) and four  main primers, targeting ver1, Omt1, Nor1 and aflR. The total mould counts ranged from 1.73±0.92 (Trunk) to 2.86±0.17 log CFU/g (Head).  The stockfish samples were contaminated with six moulds namely, Penicillium spp. (26.3%), Aspergillus niger (21.2%), Cladosporium spp.  (17.3%), Aspergillus flavus (15.0%), Aspergillus fumigatus (10.5%) and Aspergillus nidulans (9.8%). Twenty-six of the isolates were positive  to Ammonium hydroxide vapour test of which the PCR-based method detected the four targeted Aflatoxin genes. The occurrence of  aflatoxin-producing moulds in the stockfish samples of this study raises concern for public health safety. This necessitates strict  monitoring and regulation of handling of fragmented stockfish sold in Ota markets.