Genetic variability of Aspergillus flavus isolated from commercial peanut and bulgur wheat in Southern Brazil and antifungal activity of essential oils against some of the isolates
Aspergillus flavus produces carcinogenic aflatoxins. This species is divided based on the type of sclerotia produced, designated as “S” for numerous small and “L” for fewer and large. “L” strains are concerning since they are prevalent in corn, peanut, rice, and soil samples. Nearly all “S” strains and approximately 70% of “L” strains produce aflatoxins. Host specificity within isolates is not well understood and needs to be better characterized. We isolated A. flavus from commercial peanut samples from Southern Brazil and investigated their genetic variability and their genetic correlation with four A. flavus isolates previously obtained from commercial bulgur wheat in the same region. We also evaluated the antifungal activity of essential oils on some of the isolates. Eleven “L” type A. flavus strains were isolated from peanut kernels. Eight of these isolates were considered aflatoxigenic, based on thin-layer chromatography and culture techniques. The genetic biodiversity of the A. flavus isolates was analyzed using Random Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeat (ISSR) analyses, which indicated differences according to host, however, did not regarding aflatoxin production. Essential oils of oregano, thyme, cinnamon, lavender, and fennel inhibited the isolate’s growth. In conclusion, A. flavus isolates differ according to host and essential oils have potential to control this fungus.