The application of PCR in the detection of mycotoxigenic fungi in foods

Abstract

It is estimated that 25 to 50% of the crops harvested worldwide are contaminated with mycotoxins. Because of the toxic and carcinogenic potential of mycotoxins, there is an urgent need to develop detection methods that are rapid and highly specific. The highly advanced physico-chemical methods for the analysis of mycotoxins in use, have the disadvantage that highly sophisticated clean-up and/or derivatization procedures must be applied. An alternative could be the detection of the mycotoxigenic moulds themselves, especially as molecular techniques have been introduced recently as powerful tools for detecting and identifying fungi. PCR methods for the detection of aflatoxigenic Aspergilli, patulin-producing Penicillum and trichothecene-as well as fumonisin-producing Fusaria strains have been described. The usefulness of the PCR methods developed so far to monitor quality and safety in the food an feed industry was already demonstrated. Thus, PCR may be applied to the screening of agricultural commodities for the absence of mycotoxin producers prior to or even after processing. Negative results in this assay indicate that a sample should be virtually free of mycotoxins. Only the positive samples left must be analyzed for the presence of mycotoxins using physicochemical standard methods. This review does not only summarize the so far developed qualitative and quantitative PCR assays for the detection of mycotoxigenic fungi in agricultural commodities, foods and animal feeds, but describes also strategies to develop new specific PCR assays for such a detection.

Molecular Detection of Aflatoxin Producing Strains of Aspergillus Flavus from Peanut (Arachis Hypogaea)

“…Approximately 25-50% of the crops were reported to be contaminated by mycotoxins worldwide after harvesting (Konietzny and Greiner, 2003). Among these mycotoxins, aflatoxins are the most important and recognized group for polluting agricultural commodities.…”

Occurrence of toxigenic Aspergillus flavus in commercial Bulgur wheat

“…The aflatoxin producer isolates found using HPLC analysis were not detected as producers in the TLC analysis, and this may reflect differences in medium composition and culture conditions. The literature reports that only 40-50% of the A. flavus strains produce aflatoxin (Konietzny & Greiner, 2003). This inability to produce aflatoxins might be due to deletions or other mutations in the aflatoxin biosynthetic genes.…”

“…These species are also the most commonly found in several foods, where they can produce aflatoxins in several points of their production chain (Gourama & Bullerman, 1995;Pitt & Hocking, 1997). Most A. parasiticus isolates are aflatoxin producers, but only 40-50% of A. flavus isolates produce these mycotoxins (Konietzny & Greiner, 2003). Aflatoxins are primarily hepatotoxic, immunosuppressant, teratogenic, and mutagenic (Richard, 2007), and have been classified as group I carcinogens by the International Agency for Research on Cancer (International Agency for Research on Cancer, 2002).…”

Evaluation of a Real time polymerase chain reaction assay for the detectionof aflatoxin / sterigmatocystin producing strains of Aspergillus spp.

“…It is estimated that 25 to 50% of the crops harvested worldwide are contaminated with mycotoxins and the percentage is highest in tropical regions. Besides crops, food of animal origin can be contaminated with mycotoxins by carry over from mycotoxin containing animal feed (Konietzny and Greiner, 2003). There are different types of mycotoxins like aflatoxins, ochratoxins, citrinin, sterigmatocystin etc.…”