Peanut and soil populations of Aspergillus species from section Flavi in peanut-major growing region of Argentina

BARROS, G.; NESCI, A.; TORRES, A.; ETCHEVERRY, M.; CHULZE, S.

Guarajá, Brasil

Congreso; X International IUPAC Symposium. Mycotoxins and Phycotoxins; 2000

Instituto Adolfo Lutz

The purpose of this study was to obtain preliminary data of fungi contamination with species from section Flavi in harvested peanuts and in post-harvest soils from peanut-growing region of Argentina. The most frequent genera isolated were Aspergillus (50.15%), Penicillium (36%), Fusarium (7.27%), Trichoderma (2.48%), Rhizopus (1.5%), Mucor (1%), Alternaria (0.95%) and Botrytis (0.65%). All samples were negative for total aflatoxins. Isolates of Aspergillus species from section Flavi ranged 42-45% of infection in 4 samples, 30% in 5 samples, 10-20% in 6 samples and 3% in 4 samples. In adittion, the percentage of A. flavus (66%) was higher than the percentage of A. parasiticus (34%). The toxigenic capacity was determined in 21 strains: 14 strains of A. flavus produced aflatoxin B1 betwee 2.3 ug/g and 33 ug/g, 7 strains of A. parasiticus produced aflatoxin B1 between 6.9 ug/g ad 58 ug/g and aflatoxin G1 between 4.2 ug/g and 48 ug/g. Samples of post-harvest soils were examined for the presence of Aspergillus section Flavi: 34 of the 49 samples were negative, 4 samples ranged from 1 x 102 to 2 x 102 cfu/g, 6 samples ranged from 1 x 103 to 5 x 103 cfu/g and 4 samples ranged from 1 x 104 to 1.5 x 104 cfu/g. The peanuts samples were contaminated with Aspergillus section Flavi, but aflatoxin was not detected in grains, although the toxicogenic capacity was positive for all strains ecamined. Incidence of Aspergillus species in post-harvest soil samples was not significant. More studies will be carried out to determine whether the major peanut growing region of Argentina is a risk area for aflatoxin contamination.