R. Shapira et N. Paster, MULTIGENE PROBING OF AFLATOXIGENIC MOLDS IN FOOD USING PCR AND IMMUNOLOGICAL TECHNIQUES, Cereal Research Communications, 25(3), 1997, pp. 277-277
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 af
latoxin biosynthesis respectively, have been identified and their DNA
sequences published. In the present study, three primer pairs were gen
erated, each complementing the coding portion of one of the genes. DNA
extracted from mycelia of five Aspergillus species, four Penicillium
species and two Fusarium species were used as PCR templates for each o
f the primer pairs. DNA extracted from peanut, corn and three insect s
pecies commonly found in stored grains was also tested. Positive resul
ts (DNA amplification) were achieved only with DNA of the aflatoxigeni
c molds A. parasiticus and A. flavus in all three primer pairs. The de
tection limit of the PCR was determined using the primer pairs complem
enting the omt-1 and ver-1 genes. Sterile corn flour was inoculated se
parately with six different molds, each at several spore concentration
s. Positive results were only obtained following a 24-h incubation in
enriched media, with extracts of corn inoculated with A. parasiticus o
r A. flavus, even at the lowest spore concentration applied (10(2) spo
res/g). No DNA amplification was observed from corn inoculated with ot
her molds, even at the highest inoculum level (10(6) spores/g).