High Prevalence of Aflatoxin B۱ 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 (AFB۱, AFB۲, AFG۱, and AFG۲) in rice-infecting strains of A. flavus. The AF prevalence was studied in ۱۰۹ strains of A. flavus, which were collected from stored Indian rice grains from ۳۰۰ locations in the Middle Euphrates region of Iraq from ۲۰۱۵ to ۲۰۱۶. The potential AFs were extracted and quantified simultaneously using High-Performance Liquid Chromatography (HPLC) equipped with a photodiode array detector. The results revealed that ۲۹% (n= ۳۲) of strains were non-aflatoxigenic, while the remaining ۷۱% (n= ۷۷) were confirmed to be aflatoxigenic, with variable ability to produce mono-, bi-, and tri-AFs. AFB۱, AFG۲, AFG۱, and AFB۲ were produced by ۴۹ (۴۵%), ۴۴ (۴۰%), ۲۰ (۱۸%), and ۱۷ (۱۶%) strains, respectively, at various concentrations. The concentration of AFB۱ was the highest among the A. flavus strains, with a mean value of ۳,۵۶۱.۹ µg kg-۱. In conclusion, the most abundant AF synthesized by the rice-infecting A. flavus strains was AFB۱. 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.

Keywords:

Aflatoxigenic , Contamination , Indian rice , HPLC , Hygiene.