Abstract

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Aflatoxigenic molds are strains that produce aflatoxins. This study used yeast extract sucrose agar supplemented with 0.3% beta methyl cyclodextrin and 0.6% sodium desoxycholate to differentiate between aflatoxigenic and atoxigenic strains. ELISA and multiplex PCR techniques were also employed to assess aflatoxin production and detect key aflatoxin genes (aflR-1, omt-A, ver-1, nor-1). Isolates 1, 2, 3, 4, 5, 6, 7, 8, 11, and 12 were identified as atoxigenic strains, showing negative results for polyphasic beige ring assay and ELISA. However, these same isolates presented expected DNA fragments with varied banding patterns (1, 2, and 3 bands), each with different profiles of the key genes. None of these non-aflatoxigenic isolates displayed a four-band pattern with the aflatoxin biosynthesis key genes. Isolates 1, 2, 3, 8, 11, and 12 showed two band patterns each, while isolates 4, 5, and 7 presented one band each. Isolate 6 exhibited three bands. Both the banding patterns had different profiIn contrast, isolates 9 and 10 were aflatoxigenic strains and consistently showed four amplified banding patterns with the aflatoxin biosynthesis key genes. Of the non-aflatoxigenic strain genes amplified, 50.0% displayed one profile with two DNA banding patterns. Furthermore, 66.7% of the two DNA amplification banding patterns showed varied profiles. Twenty percent (20.0%) of the non-aflatoxigenic strains showed one variable profile and one DNA amplification banding pattern. The aflatoxin key gene variable profiles were observed only in non-aflatoxigenic strains. Based on the key gene profiles, the nor-1 gene had the highest frequency of occurrence (73.3%), followed by ver-1 (53.3%), omt-A (40.0%), and aflR-1 (13.3%). The variable PCR amplification of key genes in non-aflatoxigenic strains could be valuable for determining the toxicological status of food products.

Keywords: gene,PCR<Aflatoxin