Determination of Mycotoxins and Characterization of Aflatoxin-Producing Aspergillus Section Flavi in Maize from North-West Nigeria

• Maize samples from seven states in North-West Nigeria were analyzed for major mycotoxins. • Aflatoxins, fumonisins, and ochratoxin A were detected in 80.9%, 85.7%, and 61.9% of samples, respectively. • Over 40% of maize samples exceeded Nigeria’s regulatory limit for total aflatoxins (4 µg/kg). • Aspergillus section Flavi was the predominant fungal group, with 50% of isolates being aflatoxigenic. • Findings highlight the urgent need for improved post-harvest handling and storage practices. Maize ( Zea mays L. ) is a staple crop in Nigeria, playing a crucial role in ensuring national food security. However, it is highly susceptible to fungal contamination and mycotoxin production, which pose serious health risks. Despite increasing concern, data remain limited on mycotoxin contamination in maize from North-West Nigeria. This study aimed to investigate the occurrence of major mycotoxins and to characterize aflatoxin-producing Aspergillus section Flavi isolates associated with stored maize in this region. A total of 21 maize samples were collected from major grain markets across seven states: Jigawa, Kaduna, Kano, Katsina, Kebbi, Sokoto, and Zamfara. Fungal contamination and mycotoxin levels were evaluated using culture-based techniques and enzyme-linked immunosorbent assay, with aflatoxin levels in highly contaminated samples confirmed using high-performance liquid chromatography. The predominant fungi belonged to the Aspergillus section Flavi , followed by the Aspergillus sections Aspergillus and Nigri , and Rhizopus spp. Total aflatoxins were present in 80.9% (n=17) of the samples, with 42.8% (n=9) exceeding Nigeria’s regulatory limit of 4 µg/kg and 28.6% (n=6) surpassing the European Union (EU) maximum limit of 10 µg/kg. Fumonisins were present in 85.7% of samples, although all concentrations were below the EU maximum limit of 4,000 µg/kg. Ochratoxin A was identified in 61.9% of the samples, albeit at low concentrations in several cases. The analysis of the Aspergillus section Flavi isolates revealed that 50% were aflatoxigenic. All toxigenic isolates were identified as A. flavus , while the non-toxigenic strains were A. oryzae and A. tamarii . These findings highlight widespread contamination of maize in North-West Nigeria by aflatoxins and aflatoxigenic fungi, raising public health concerns. Future efforts should prioritize improving pre- and post-harvest practices, strengthening regulations, and implementing regular monitoring to mitigate mycotoxin contamination.