Purpose: Here, we report the utility of a small bench top, automated instrument, the Maxwell RSC and a new kit chemistry for purification of amplifiable DNA from a variety of foods and feed. We tested seeds for GMO and meat for species authentication.
Methods: Nucleic acid was extracted from 50-200 mg ground seeds or meat using the Maxwell RSC PureFood GMO and Authentication kit. For GMO testing, extracted DNA from corn, soybean and canola was tested for the presence of cauliflower mosaic virus (CaMV) or Figwort Mosaic Virus (FMV) promoter and a plant-specific sequence. For seafood authentication, DNA was extracted from fish and amplified using endpoint PCR of cytochrome b, followed by restriction enzyme digestion and RFLP analysis. Ground beef and pork testing focused on isolation of nucleic acid from low level mixtures of pork in beef with analysis by quantitative PCR of pork- or beef-specific mitochondrial DNA sequences.
Results: The seed GMO testing showed amplification of virus promoters in GMO labeled samples and no amplification or only trace amounts in the non-GMO samples. The fish samples were identified as correctly matching the species listed on labels. The mixed pork and beef sample amplification results correlated to the percentage of the mixture. DNA purification of the same sample in 3 different experiments was reproducible (n=8 each run, CVs < 13%). There was no detectable cross-contamination and no inhibition of amplification in the eluates.
Significance: These studies together demonstrate the utility of the Maxwell RSC System for automated purification of food DNA upstream of amplification-based GMO and authentication testing.