Comparison of DNA extraction methods from muscle of canned tuna for species identification

Four DNA extraction methods from canned tuna in different liquid media were compared. Wizard DNA Clean Up system with proteinase K previous digestion, Nucleospin (Clontech), GenomicPrep (Amersham Pharmacia Biotech) and the CTAB precipitation method were employed. DNA was extracted from four different canned tuna of the same tuna species, light tuna (Thunnus albacares): light tuna in brine, oil, vinegar and with a tomato sauce. Three samples of each type of product were analysed with the different methods. Quantity and quality of DNA extracted was evaluated using the ratio A260/A280. Also, quality was evaluated by using a set of designed primers amplifying fragments of cytochrome b of increasing size ranging from 100 bp to 300 bp. Results show that DNA extraction from canned tuna preserved in different liquid media could be optimized employing a specific DNA extraction method in each case. Best results were obtained with CTAB method for canned tuna in oil and for canned tuna in vinegar, with Wizard method for canned tuna in brine and with Genomic Prep method for canned tuna with tomato sauce.