Validated method for quantification of genetically modified organisms in samples of maize flour

Area of Science:

• Food safety analysis
• Molecular biology techniques
• Biotechnology applications

Background:

• Detection of genetically modified (GM) ingredients necessitates sensitive and accurate methods for trace DNA quantification.
• Real-time PCR (RT-PCR) offers advantages over ELISA for DNA detection due to simpler sample preparation and lower detection limits.
• Previous RT-PCR methods using SYBR Green were found to be sensitive to sample matrices and genomic DNA content, affecting result interpretation.

Purpose of the Study:

• To develop and validate a highly accurate and sensitive real-time DNA quantification method for detecting trace amounts of biotechnology-derived DNA.
• To establish a reliable method for quantifying GM ingredients at levels as low as 0.5% or 1% in food products and raw materials.
• To overcome the limitations of previous RT-PCR methods sensitive to sample matrices.

Main Methods:

• DNA extraction using the CTAB method was chosen for its flexibility and DNA yield/quality.
• A real-time DNA quantification assay was developed utilizing the TaqMan probe method.
• The method's performance was evaluated using purified plasmid standards and complex genomic DNA matrices.
• Statistical analysis included assessing homology of variance, linearity, standard curve accuracy, and standard deviation using ValiData software.

Main Results:

• The developed TaqMan probe-based real-time PCR method demonstrated high accuracy and sensitivity.
• Detection limits were established to be lower than 18 DNA copies per sample.
• The method proved applicable and comparable for both highly purified plasmid standards and complex genomic DNA samples.
• Validation using ValiData confirmed the reliability of the quantification results.

Conclusions:

• The TaqMan probe-based real-time PCR method provides a sensitive and accurate approach for quantifying trace amounts of biotechnology-derived DNA.
• This method is suitable for detecting low levels of GM ingredients in food and raw materials, addressing limitations of previous techniques.
• The validated method offers reliable results across various sample types, enhancing food safety testing capabilities.