Studies on Aflatoxin-Producing Fungi in Stored Maize (Zea mays L.) and the Use of Bentonite Clay in Reducing their Toxin Levels

Aflatoxins are a group of mycotoxins produced by Aspergillus fungi that are both toxic and carcinogenic to animals and humans; however, studies on their removal by natural substances have had great success, and bentonite was seen as a possible remedy in this aspect. The study on aflatoxin-producing fungi in stored Maize (Zea mays L.) was conducted on stored maize collected from Muna Market, Maiduguri, based on their year of harvest (2015, 2016, 2017, and 2018). Out of which a total of 49 isolates consisting of Aspergillus spp, Talaromyces islandicus, and Scopulariopsis candida were obtained, these include Aspergillus niger 38.78%, A. flavus 12.24%, A. oryzae 12.24%, A. fumigatus 10.20%, A. parvisclerotigenus 6.12%, A. aflatoxiformans 4.08%, Scopulariopsis candida 14.29%, and Talaromyces islandicus 2.04%. The molecular assay confirms the identity of the isolates amplified using universal ITS primers with 100% query and identity, except sample A (A. aflatoxiformans 087-A2) has 99.62% identity compared with NCBI library. The total aflatoxin profile of the stored maize collected for the 2015 harvest year was 100 ppb before treatment and reduced to 2.2 ppb after treatment. In contrast, the 2016 maize sample, which had 1.8 ppb before treatment, reduced to 1.7 ppb; the 2017 sample had 1.9 ppb reduced to 0.9 ppb; and 2018 had 3 ppb before treatment reduced to 0.3 ppb after treatment; the AfB1 profiles depict that 2015 maize sample had 60 ppb before treatment and reduced to 1ppb after treatment. The 2016 maize sample had one ppb reduced to 0.9 ppb, whereas the 2017 sample had 1 ppb and reduced to 0.6 ppb, and 2018 had 2 ppb and detoxified to 0 ppb after treatment. The Bentonite clay used was found to reduce the toxin levels of the stored maize.