High Prevalence of Aflatoxin B1 in Aspergillus flavus Infecting Stored Rice Grains

One of the best-known rice-infecting microorganisms is Aspergillus flavus, which produces toxic metabolites known as Aflatoxins (AFs). This study was designed to detect potential simultaneous biosynthesis of the four main AFs (AFB1, AFB2, AFG1, and AFG2) in rice-infecting strains of A. flavus. The AF prevalence was studied in 109 strains of A. flavus, which were collected from stored Indian rice grains from 300 locations in the Middle Euphrates region of Iraq from 2015 to 2016. The potential AFs were extracted and quantified simultaneously using High-Performance Liquid Chromatography (HPLC) equipped with a photodiode array detector. The results revealed that 29% (n= 32) of strains were non-aflatoxigenic, while the remaining 71% (n= 77) were confirmed to be aflatoxigenic, with variable ability to produce mono-, bi-, and tri-AFs. AFB1, AFG2, AFG1, and AFB2 were produced by 49 (45%), 44 (40%), 20 (18%), and 17 (16%) strains, respectively, at various concentrations. The concentration of AFB1 was the highest among the A. flavus strains, with a mean value of 3,561.9 µg kg-1. In conclusion, the most abundant AF synthesized by the rice-infecting A. flavus strains was AFB1. Contamination with AFs continues to pose potential health risks to animals as well as humans. These results clearly indicate that the improper storage conditions of rice in Iraq were favourable for the growth of A. flavus and contamination with AFs. National-level studies are mandatory to avoid foodborne intoxications. Strict regulations should be devised and imposed to prevent synthesis of AFs on rice grains.