Shrimps and prawns are quite nutritious and provide quality protein, omega-3 fatty acids, certain antioxidants, vitamins and minerals, like iodine. Therefore, they are healthy food for human consumption. In order to avoid fish fraud in value added products, they need to be authenticated properly. In this study, six frozen shrimp species was correctly identified using DNA barcoding of mt-COI gene. The genomic DNA isolated from frozen shrimp samples showed greater than 10 kb. Their amplified products showed 564-770 bp of mt-COI gene. The BLAST results for the subjected labeled frozen shrimp sample Litopenaeus vannamei showed 99-100% similarity with the same species sequences available in the NCBI database. The sequences of five unlabeled samples (two samples taken from two independent packets, and three samples taken from one mixed shrimp packet) showed maximum similarity with the sequences available in the NCBI database and exactly identified as Fenneropenaeus merguiensis and Penaeus monodon, and Fenneropenaeus indicus, Penaeus semisulcatus and Penaeus monodon respectively. These six sequences showed more variable amino acid sites than the identical and similar amino acid residues within themselves. The base composition of the COI gene fragment varied among these six species, AT biases ranged from 61.5% to 67.51% (P. semisulcatus and P. monodon taken from unlabeled mixed packet) and the GC biased ranged between 32.9-38.6%, (P. monodon and P. semisulcatus) which indicates less NUMTs gene. The inter species divergence rate calculated between these six species was ranged between 0.434-3.401 (L. vennamei Vs. F. indicus, and F. merguiensis Vs. P. monodon, taken from unlabeled independent packet). The phylogenetic information revealed that nucleotide substitutions occurred at different levels than that of nucleotide saturation. The phylogenetic tree topology of these six shrimp species formed as three clusters in which F. indicus aligned at the base of the tree as a separate clade, in the second cluster P. semisulcatus also formed a separate clade and in the other cluster F. merguiensis, L. vannamei formed as separate clades, and P. monodon of independent packet and mixed packet formed a sister taxon with each other with the bootstrap value of 95. Therefore, any unlabeled shrimp/prawn/seafood species can be clearly identified and differentiated using mt-COI gene.
Key words: Frozen shrimp, mt-COI gene, Sequence, Phylogenetic tree
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