Phylogenetic and Gene Expression of Norsolorinic Acid Analysis of Aflatoxigenic Strains and Quantification of Aflatoxin B1 Levels into White Rice Grains in Kenya

Abstract

The most important pathogens of global significance in food security are mycotoxigenic fungi. Aflatoxigenic strains contamination in rice grains can lead to a health risk for consumers. Under appropriate conditions, aflatoxigenic fungi can grow and subsequently produce aflatoxins.  Aflatoxin poses a real threat to food safety and security and destroys approximately 25 % of the world's food crops and every year 420,000 people die from consuming contaminated food causing an estimated loss of 33 million healthy life years. This study screened Norsoloric Acid gene involved in the biosynthesis pathway, gene expression profile of aflatoxigenic strains characterized from rice grains, and assessed aflatoxin B1 levels in white rice grains. We combine the use of molecular techniques and Enzyme-Linked Immunosorbent Assay to detect aflatoxin biosynthesis aflD gene and quantify gene expression profile, and analyzed aflatoxin B1 levels, respectively. The results shown that all aflatoxigenic strains analyzed in this study are clustered within the same clade based on the aflD gene. The targeted aflD gene for expression was amplified in all aflatoxigenic strains with higher relative level in Aspergillus flavus but no relative expression shown in Aspergillus fumigatus. Enzyme-Linked Immunosorbent Assay showed that 43.1 % of the samples were found positive, with15.9 % being local rice and 27.2 % imported rice. Notably, 11.3 % of analyzed samples were above the recommended aflatoxin B1 in rice grains established by European Union with aflatoxin concentration ranging between 0 μg/kg to 3.2 μg/kg. These results are indicative of exposure of the population to aflatoxin B1 and possible health hazard. Our study reveals high levels of aflatoxin B1 contamination in both imported and local rice grains in Kenya. This study highlights the aflatoxigenic strains which are the potential aflatoxins contamination of different types of foodstuffs.