Molecular Detection and Biochemical Profiling of Mycotoxigenic Fungi Isolated from Palm Oil Sold within Bauchi Metropolis, Nigeria

Abstract

Background: Palm oil is a major dietary staple in Nigeria, but its production, transportation, and sale under informal market conditions expose it to fungal contamination and potential mycotoxin accumulation. Mycotoxigenic fungi such as Fusarium, Aspergillus, and Penicillium have been frequently isolated from palm oil, yet conventional phenotypic identification alone cannot reliably determine their toxigenic potential. Molecular techniques provide improved accuracy for detecting mycotoxin-producing strains. Aim: This study aimed to detect and molecularly characterize mycotoxigenic fungi isolated from palm oil sold within Bauchi metropolis, with particular emphasis on fumnonisin-producing Fusarium species. Place and Duration of Study: The study was carried out in Bauchi Metropolis, Bauchi State, Nigeria. Palm oil samples were collected from four major markets Muda-Lawal, Wunti, Central, and Yelwa markets and laboratory analyses were conducted at the Microbiology Laboratory, Abubakar Tafawa Balewa University (ATBU), Bauchi. The study was conducted during the active trading period within the study timeframe. Methodology: A total of 100 palm oil samples were randomly collected (25 from each market) using sterile containers. Samples were transported to the laboratory for analysis. Mycotoxin screening was performed using High Performance Liquid Chromatography (HPLC) to detect aflatoxins, fumonisins, deoxynivalenol, and zearalenone. Fungal isolates previously obtained were subjected to genomic DNA extraction using the CTAB method. Polymerase Chain Reaction (PCR) was employed to detect the fumonisin biosynthetic gene (FUM1) using specific primers, followed by agarose gel electrophoresis for visualization of amplified products. Molecular findings were compared with phenotypic fungal profiles. Results: HPLC analysis revealed that only one sample (Muda 7) was contaminated with mycotoxins, showing fumonisin B₁ at 6.8 µg/kg and fumonisin/HT-2 toxin at 117.8 µg/kg, while aflatoxins, deoxynivalenol, and zearalenone were not detected in any samples. PCR amplification produced a ~953 bp FUM1 gene fragment, confirming the presence of a fumonisin-producing Fusarium strain. Genotypic analysis showed that among the isolated fungi, only Fusarium spp. harbored the FUM1 gene, while Aspergillus, Penicillium, and Mucor species showed no detectable mycotoxin biosynthesis genes. Conclusion: The study confirms the presence of fumonisin-producing Fusarium species in palm oil sold within Bauchi metropolis using molecular detection methods. Although overall mycotoxin occurrence was low, the detection of the FUM1 gene and measurable fumonisin levels in palm oil highlights a potential food safety risk. The findings demonstrate that molecular techniques are essential for accurate identification of mycotoxigenic fungi and should complement conventional methods. Routine molecular surveillance and improved handling and storage practices are recommended to minimize mycotoxin contamination and protect public health.