Barcoding Tetrahymena: Discriminating Species and Identifying Unknowns Using the Cytochrome c Oxidase Subunit I (cox-1) Barcode

DNA barcoding using the mitochondrial cytochrome c oxidase subunit I (cox-1) gene has recently gained popularity as a tool for species identification of a variety of taxa. The primary objective of our research was to explore the efficacy of using cox-1 barcoding for species identification within the genus Tetrahymena . We first increased intraspecific sampling for Tetrahymena canadensis, Tetrahymena hegewischi, Tetrahymena pyriformis, Tetrahymena rostrata, Tetrahymena thermophila, and Tetrahymena tropicalis . Increased sampling efforts show that intraspecific sequence divergence is typically less than 1%, though it may be more in some species. The barcoding also showed that some strains might be misidentified or mislabeled. We also used cox-1 barcodes to provide species identifications for 51 unidentified environmental isolates, with a success rate of 98%. Thus, cox-1 barcoding is an invaluable tool for protistologists, especially when used in conjunction with morphological studies .