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Last Document: 3.1.2  Methods developed to detect GMOs and published in scientific journals

Table of Contents  Foods derived from genetically modified organisms and detection methods

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3.1.3 Highly specialised reports on the detection of GMOs in food unavailable in databases

This section concerns articles or methods mentioned in special reports (e.g. reports commissioned by national authorities), annual reports from food research institutes, petition documents from companies or information presented as posters at conferences. References to these works cannot be easily found by literature searches in commonly available databases; dissemination of these references occurs mainly through personal communications.

Specialised reports of this nature have described detection methods for genetic elements used in the generation of transgenic corn (Waiblinger et al., 1997; Pietsch and Waiblinger, 1996; Pietsch et al., 1997; PGS-petition, 1995), cotton (DuPont-petition), potato (Pietsch et al., 1997; Waiblinger et al., 1997), sugar beet (Pietsch et al., 1997; Waiblinger et al., 1997), soybean (Pietsch et al., 1997; Waiblinger et al., 1997; Wurz and Willmund, 1997), tobacco (Kriete et al., 1996) and tomato (Pietsch et al., 1997; Waiblinger et al., 1997; Pietsch and Waiblinger, 1996; Zeneca-petition, 1994). Almost all of these methods were PCR-based and were applied to approved genetically engineered products or to genetic elements that have been frequently used for the generation of the approved transgenic plants (Pietsch et al., 1997; Waiblinger et al., 1997). Experimental details such as primer sequences, amplicon length and cycling parameter are summarised in  Primer sequences and amplicon length in PCR-assays to detect GMOs.

An identification procedure for tomato paste manufactured from genetically engineered tomatoes from Zeneca and sold in the UK in 1996 has been reported (press release No. 057/29.5.96 of the University of Bremen, Germany). The method is based on PCR amplification of a 506 basepair fragment from the nptII gene (personal communication G. Meyer, Hanse Analytik, Bremen). That a DNA fragment of this size could be successfully amplified from a heat-treated sample with low pH (approximately pH 3) may be surprising at first glance. Other sources, however, have also reported that DNA has been amplified from similar samples, even when the length of the chosen amplicons was considerably shorter, using 137 basepair (Personal communication H.U. Waiblinger, Chemische Landesuntersuchungsanstalt, Freiburg; Allmann et al., 1993) and 226 basepair fragments (Ford et al., 1996; Barallon et al., 1996).

There have also been reports of attempts to identify artificially-introduced DNA in bread (Annual Report BFE, 1995). In a model detection system, flour from rye was spiked with E. coli cells or DNA, containing a phytase gene. E. coli DNA could neither be detected in fermented dough nor in the final bread product. When large quantities of bacterial cells (more than 1010 cfu/g) were added, the presence of foreign DNA was detectable. Such quantities, however, were considered to be highly unlikely for 'realistic' applications. Whereas no commercial approval of any cereal variety exists at present, a genetically modified bakers' yeast developed for bread making has been approved in the UK, although it is reputedly not in use.

Several publications have focused on the detection of DNA derived from decomposing transgenic plant material in the soil. The PCR systems described were specific for genetic elements that had been introduced in genetically engineered corn (synthetic pat gene) and rapeseed (pat, P-35S) (Ernst et al., 1996; Feldmann et al., 1996; Kirchhof et al., 1996), or derived from the so-called 'Changins-potato' (PVY-cp, nptII) field tested in Switzerland (Stax et al., 1994). In addition, the primers used for the detection of the nptII gene in soil bacteria or other environmental sources using genuine (Smalla et al., 1993) or nested PCR (Tsushima et al., 1995) may also be applicable for the detection of this frequently used transgene in foods.