Co-Authors:
Shapira, R., Inst. Biochem., Food Sci., and Nutr., Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel
Paster, N., Department of Stored Products, Agricultural Research Organization, Volcani Center, Bet-Dagan 50250, Israel
Eyal, O., Inst. Biochem., Food Sci., and Nutr., Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel
Menasherov, M., Department of Stored Products, Agricultural Research Organization, Volcani Center, Bet-Dagan 50250, Israel
Mett, A., Inst. Biochem., Food Sci., and Nutr., Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot 76100, Israel
Salomon, R., Department of Virology, Agricultural Research Organization, Volcani Center, Bet-Dagan 50250, Israel
Abstract:
Aflatoxins are carcinogenic metabolites produced by several members of the Aspergillus flavus group in grains and foods. Three genes, ver-1, omt-1, and apa-2, coding for key enzymes and a regulatory factor in aflatoxin biosynthesis, respectively, have been identified, and their DNA sequences have been published. In the present study, three primer pairs, each complementing the coding portion of one of the genes, were generated. DNA extracted from mycelia of five Aspergillus species, four Penicillium species, and two Fusarium species was used as PCR template for each of the primer pairs. DNA extracted from peanut, corn, and three insect species commonly found in stored grains was also tested. Positive results (DNA amplification) were achieved only with DNA of the aflatoxigenic molds Aspergillus parasiticus and A .flavus in all three primer pairs. The detection limit of the PCR was determined by using the primer pairs complementing the omt-1 and ver-1 genes. Sterile corn flour was inoculated separately with six different molds, each at several spore concentrations. Positive results were obtained only after a 24-h incubation in enriched media, with extracts of corn inoculated with A. parasiticus or A. flavus, even at the lowest spore concentration applied (102 spores per g). No DNA amplification was observed from corn inoculated with other molds, even at the highest inoculum level (106 spores per g). It is concluded that genes involved in the aflatoxin biosynthetic pathway may form the basis for an accurate, sensitive, and specific detection system, using PCR, for aflatoxigenic strains in grains and foods.