OCCURRENCE OF ASPERGILLUS-FLAVUS STRAINS AND AFLATOXINS IN CORN FROM SANTA-FE, ARGENTINA

It has been demonstrated in several agricultural regions all around th e world that Aspergillus flavus can infect corn grains and produce afl atoxins even before the harvest. It is also known that the incidence a nd levels of contamination of cereals factors. In the present work, th e incidence of aflatoxins in corn grain from the central and northern areas of Santa Fe province in Argentina was studied. The relationship between the extent of kernel infection by the fungus and the presence of aflatoxins in the samples was examinated. The isolation and identif ication of A.flavus were carried out by plating dilutions of the groun d kernels on dichloran-rose bengal-chloramphenicol agar (DRBC). Simult aneously, kernels were superficially sterilized with 10% commercial CI ONa and plated on potato-dextrose-chloramphenicol agar (PDA+C). The an alysis of aflatoxins B1, B2, G1 and G2 was performed by thin layer chr omatography (TLC) according with Norma LRAM 14803 (Argentina). A.flavu s Link:Fr. was identified in 63.3% of the corn samples. Colonized kern els ranged from 2.5 to 25% and counts on DRBC were in the order of 10( 3) CFU/g. Two samples colonized by A.flavus contained aflatoxins B1 an d B2 (50 mu/kg of aflatoxin B1 and 30 mu g/kg of aflatoxin B2, and 30 mu g/kg of aflatoxin B1, and traces of aflatoxin B2, respectively). On e sample contained only aflatoxin B1 (22 mu/kg). According to these re sults, it may be concluded that the incidence of A.flavus observed con stitutes a call in attention with respect to the conditions required f or storage and transportation of the grains, to minimize the prolifera tion of the fungus and the production of aflatoxins in these stages. A lthough the incidence of aflatoxins in the samples of grains was rathe r low, the levels of aflatoxin B1 recorded in the positive samples wer e higher than those recommended -or given as adivsory levels for human foods, by most countries in the world.