Aspergillus flavus biomass in harvested maize in Kenya and Tanzania and its relation to aflatoxin levels

Abstract

Abstract Controlling occurrence of aflatoxins in foods must go along with managing the fungi responsible for their production. Abundance and diversity of aflatoxin producing Aspergillus flavus account for accumulation of the toxins in crops, which has been a persistent threat for public health and economy in tropical developing countries. A study was conducted to investigate occurrence and level of A. flavus and relate them to aflatoxin level in maize in Kenya and Tanzania. A total of 786 maize samples were collected at harvesting in selected areas of the two countries for the analysis. Fungal abundance in the samples was expressed as amount of fungal DNA relative to maize DNA. The fungal DNA was quantified by qPCR, targeting internal transcribed space (ITS) gene whereas in maize DNA was quantified through alpha-tubulin gene. The two genes are known to be conserved. Aflatoxins were quantified using ultra-high performance liquid chromatography, coupled to ultra-high sensitivity, ultra-fast triple quadrupole, tandem-mass spectrophotometer. A flavus was detected in 88.5% of 786 tested samples and average fungal load for the samples (log host/pathogen ratio) was 5.53. Aflatoxin occurrence was positive in 31.9% of the samples at an average level of 2.3 ± 0.643 ppb. There was a positive relationship between occurrence and level if the aflatoxin B1 and presence and biomass of A. flavus was proved statistically. The findings of this study intensify the need to give substantial attention on preharvest control of A. flavus in cereal fields as an effort of controlling accumulation of aflatoxin B1 in foods.