Quantitative bioluminometric method for DNA-based species/varietal identification in food authenticity assessment

Area of Science:

• Molecular Biology
• Biotechnology
• Genetics

Background:

• Species authentication is crucial for agriculture and trade.
• Distinguishing closely related species, such as coffee varieties, presents analytical challenges.
• Single-nucleotide polymorphisms (SNPs) offer high specificity for genetic discrimination.

Purpose of the Study:

• To develop and validate a quantitative method for species determination using SNPs.
• To accurately quantify the proportions of Arabica and Robusta coffee species.
• To establish a high-throughput, automated assay for genetic analysis.

Main Methods:

• Utilized a specific SNP in the coffee chloroplastic trnL(UAA)-trnF(GAA) intraspacer region for discrimination.
• Employed polymerase chain reaction (PCR) followed by primer extension with species-specific primers.
• Incorporated biotin for capture on streptavidin-coated microtiter plates and quantified using aequorin bioluminescence.

Main Results:

• Demonstrated a linear relationship between luminescence signal and the percentage of each coffee species.
• Achieved accurate and reproducible quantification of Arabica and Robusta mixtures.
• The method leverages one species as an internal standard due to DNA fragment similarity.

Conclusions:

• The SNP-based method provides accurate and reproducible species quantification.
• The bioluminescent assay is rapid (3-second measurement) and suitable for automation.
• This technique enables high-throughput authentication of closely related species, exemplified by coffee.