Validation and comparison of four DNA extraction methods for genetically modified organisms analysis: From DNA quality control to quantification of genetically modified content in real-life samples matrices

Background

The analysis of genetically modified organisms (GMOs) in food and feed is broadly based on the detection of target DNA sequences using PCR-based methods. The first step of a typical workflow in a GMO testing laboratory is DNA extraction and purification. Several DNA extraction methods have been described for this purpose so far. Whatever the method adopted, the yield and the quality of the extracted DNA are essential factors for the success of GMO analysis.

Results

The DNA extraction yield was variable between the different methods, while quality and efficiency appeared comparable. Each method allowed a different yield and a slight correlation between inhibition and the food/feed matrix extracted was observed. Particularly for challenging matrices, the method used for DNA extraction has a remarkable influence on both the quality and quantity of the recovered DNA. Small variations in value % GM content were observed in complex, heterogeneous matrices but not in CRMs and homogeneous matrices.

Conclusions

In this study, the purpose is not to establish the best method of extraction but to examine several parameters that play an important role in GMO detection and verify a possible effect on the quantified GMO percentage. In particular, it was found that the yield and quality of extracted DNA depends on the type of sample, notably the degree of processing, composition, particle size, and the protocol used, especially in relation to sample intake. The slightly different GM content observed in heterogeneous matrices could raise doubt in the case of samples close to the legal threshold.