Molecular characterisation of Aspergillus flavus on imported maize

Maize is a vital staple crop in Kenya, serving as a primary source of food and feed. Contamination of maize (Zea mays) by Aspergillus flavus and the subsequent production of aflatoxins pose significant threats to food safety and human health. The risk of A. flavus contamination on imported maize at both gazetted and un-gazetted points of entry has not been extensively studied. The primary objective of this study was to examine the genotypic, phenotypic, and aflatoxigenic traits of A. flavus biovars derived from imported maize at Gazetted and Un-gazetted Points of Entries in Kenya. Furthermore, the study sought to establish the phylogenetic relationships among the identified A. flavus strains. A total of 600 imported maize samples were tested for aflatoxin contamination using the Total aflatoxin ELISA test. Out of 600 samples, 4.17% tested positive and were further subjected to morphological and molecular studies. The morphological analysis revealed the presence of 13 biovars of A. flavus. Micro-morphologically, variations were observed in spore color, size, structure, conidiophore structure, and vesicle shape. The specific primers Calmodulin (CaM), the ITS1-5.8S-ITS2 region of the ribosomal DNA was successfully amplified in 10 out of the 13 biovars that were presumed to be A. flavus, confirming their positive identification as A. flavus. A single band of approximately 700 bp, which corresponds to the expected size of the ITS region in Aspergillus flavus, was observed in 10 out of the 13 biovars. This indicates the presence of A. flavus DNA in those biovars. The amplification of the ITS region provides a specific molecular marker for the identification of A. flavus. These findings highlight the significance of aflQ (ordA) and aflD (nor-1) genes as reliable markers for evaluating the aflatoxigenic potential of A. .