Differentiation of animal species in food by oligonucleotide microarray hybridization

Oligonucleotide microarray hybridization analysis of polymerase chain reaction (PCR) products from the mitochondrial cytochrome b gene DNA was applied to identify different animal species in meat and cheese food samples. A pair of universal primers binding to conserved regions of the vertebrate mitochondrial cytochrome b gene was used to amplify a 377 bp fragment with internal regions of high inter-species variability. PCR products of cattle, pig, chicken, turkey, sheep and goat were unequivocally identified by hybridization with species-specific probe sequences immobilized on an oligonucleotide microarray. In meat samples, 0.1% admixtures of beef or chicken meat were still detectable. By using this new PCR-based DNA chip hybridization for the analysis of 24 commercial food samples from routine control, the simultaneous species composition of mixtures with up to four different species could be determined in a single experiment. The results agreed well with those from the reference methods performed at the local food control authority, which are a combination of enzyme-linked immunosorbent assay (ELISA), species-specific PCR and PCR–RFLP (restriction fragment length polymorphism). Thus, the DNA chip hybridization analysis of cytochrome b PCR products offers a new way for rapid and sensitive species differentiation in food.