The application of PCR–RFLP and FINS for species identification used in sea cucumbers (Aspidochirotida: Stichopodidae) products from the market

Sea cucumbers are traditional, delicious and luxurious seafood in Asia. They are usually provided to the consumers in the marketing formats of dried or frozen products. At the commercial level, they are much different not only in flavor, but also in price. The processing treatment makes them difficult for species identification based on morphological characterization. In this study, two molecular methods are developed to identify six species belonging to family Stichopodidae in commercial products. The first one is PCR–RFLP (polymerase chain reaction–restriction fragment length polymorphism), which uses PCR amplification of a common 570 bp fragment of the 16S rRNA gene and follows codigestion with two restriction enzymes (XmnI and MwoI). Another one is FINS (forensically informative nucleotide sequencing) of the 16S rRNA gene, and the key of the method is the phylogenetic analysis of 16S rRNA gene sequences. The PCR–RFLP methodology can be used to authenticate the species tested in the present study and allow us to detect a fraudulent labeling of frozen Apostichopus japonicus product. And the FINS methodology confirms that the species substituted for A. japonicus belongs to the genera Isostichopus. Therefore, two molecular tools really provide convenient, useful and academic techniques to authenticate the species of commercial sea cucumber products.