Aflatoxin B1 producing potential of Aspergillus flavusstrains isolated from stored rice grains

Aflatoxin B 1 (AFB1) producing potential of different strains of Aspergillus flavus, isolated from 1,200 stored rice grains collected from 43 locations in 20 rice growing states in India was investigated. Eighty-five strains of A. flavus were isolated from the discolored rice grains and tested for their AFB1 producing potential on different agar media. Among these, 43 strains were identified as AFB1 producers (ranging 0.2 – 40 μg/g agar). All the 43 strains of A. flavus produced AFB1 on yeast extract sucrose agar media (YES). However, 65% of the strains produced AFB1 on Czapek’s agar, 53% of the strains on potato dextrose agar (PDA) and none of the strains on Aspergillus flavus and parasiticus agar media (AFPA). The strain, DRAf 009 produced maximum AFB1 (4.0 – 40 μg/g agar) on all the agar media tested. Five strains of A. flavus producing high amounts of AFB1 identified in agar media were evaluated for their AFB1 production on milled rice cultivars. The five strains produced AFB1 on all the rice cultivars. Out of 5 strains, the DRAf 009 produced maximum AFB1 (386 – 415 μg/g grain) on all the rice cultivars tested.