Development of a PCR protocol to detect aflatoxigenic molds in food products.
Aflatoxins are secondary metabolites produced mainly by Aspergillus species growing in foodstuffs. Because aflatoxins have important health effects, the detection of early contamination of foods by aflatoxigenic molds should be useful. In the present work, a reliable conventional  PCR method for detecting aflatoxigenic molds of various species was developed. Fifty-six aflatoxigenic and nonaflatoxigenic strains commonly reported in foodstuffs were tested. Aflatoxin production was first confirmed by micellar electrokinetic capillary electrophoresis or/and high-pressure  liquid chromatography-mass spectrometry. Based on the conserved regions of the O-methyltransferase gene (omt-1) involved in the aflatoxin biosynthetic pathway, six primer pairs were designed. With only the designed primer pair AFF1-AFR3, the expected PCR product (381 bp)  was obtained in all of the tested aflatoxigenic strains of various species and genera. Amplification products were not obtained with this primer pair for any of the nonaflatoxigenic reference molds. However, an amplicon of 453 bp was obtained for all aflatoxigenic and nonaflatoxigenic mold  reference strains with a PCR protocol based on the constitutive fungal β-tubulin gene, which was used as a positive fungal control. The PCR protocol based on omt-1 detected as little as 15 pg of DNA from aflatoxigenic molds and 10(2) to 10(3) CFU/g in contaminated  food samples. This PCR protocol should be used as a routine technique to detect aflatoxigenic molds in foods.
Higiene y Seguridad Alimentaria, Facultad de Veterinaria, Universidad de Extremadura, Avda. de la Universidad s/n, 10003-Cáceres, Spain.
M Isabel
MI
Luque
Alicia
A
Rodríguez
María J
MJ
Andrade
Alberto
A
Martín
Juan J
JJ
Córdoba
D000348:Aflatoxins / Q000032:analysis* / Q000096:biosynthesis / Q000737:chemistry; D001230:Aspergillus / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism; D001483:Base Sequence; D015169:Colony Count, Microbial; D004271:DNA, Fungal / Q000032:analysis; D005506:Food Contamination / Q000032:analysis*; D005784:Gene Amplification; D005800:Genes, Fungal; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D013045:Species Specificity
D000348:Aflatoxins; D004271:DNA, Fungal