Aflatoxin and ochratoxin producers from stored peanuts from Cordoba province , Argentina

MAGNOLI, C.; ASTORECA, A.; PONSONE, L.; CHIACCHIERA, S.; DALCERO, A.

Maryland, USA

Simposio; XI IUPAC Symposium on Mycotoxinsa and Phycotoxins; 2004

IUPAC

Peanut (Arachis hypogaea L) is an important crop in Argentina, with Córdoba Province accounting for approximately 98% of total peanut production. The aims of this work were to isolate and identify species of Aspergillus sections Flavi and Nigri from peanut seeds, and to evaluate their aflatoxigenic and ochratoxigenic capacities. A total of forty-seven peanut samples were collected from a silo of a storage plant located in the south of Córdoba Province, Argentina. The species were isolated by direct plating method with superficial disinfection of fruits. The culture medium used was Dichloran Glicerol 18% (DG18). The fungi were identified according to Klich and  Pitt, (1988), Pitt and Hocking (1997), Samson et al. (2000). The AFs production by Aspergillus, section Flavi was determined by the methodology described by Geisen et al. 1996. The OA production by Aspergillus, section Nigri was determined by Téren et al. (1996) and Scudamore and MacDonald (1998).The frequency of peanut seeds contaminated by A. flavus species was 100 and 72%, respectively. Out of 100 Aspergillus flavus strains evaluated, 65  produced AFB1 in malt extract agar (MEA), with levels ranging from 0.4 to 38 ng g-1 of mycelia; and among the A. parasiticus isolates (5 strains), four were AFB1 and AFG1 producers. The species A. niger var. niger and A. niger var. awamori were isolated in 89% and  68% of the samples. The principal specie producers of ochratoxins, A. carbonarius, was isolated in low percentage of samples (4%). From 164 Aspergillus section Nigri strains, 26.22% produced OA in yeast extract broth (YES), with levels ranging from 2 to 18 ng mL-1 of medium. In the specie A. carbonarius a high percentage of OTA producers (57%) was detected, while 24 and 23% of A. niger var. niger and A. niger var. awamori were OA producers, respectively.