Molecular Microbiology Laboratory, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Department of Marine Biotechnology, Ensenada, B.C, México.
BACKGROUND: Dunaliella salina is the most important species of the genus for beta-carotene production. Several investigations have demonstrated that D. salina produces more than 10% dry weight of pigment and that the species grows in salt saturated lagoons. High plasticity in the green stage and the almost indistinguishable differences in the red phase make identification and differentiation of species and ecotypes very difficult and time consuming. RESULTS: In this work, we applied our intron-sizing method to compare the 18S rDNA fingerprint between D. salina (CCAP 19/18), D. salina/bardawil (UTEX LB2538) and beta-carotene hyperproducing strains of Dunaliella isolated from salt saturated lagoons in Baja, Mexico. All hyperproducer strains reached beta-carotene levels of about 10 pg/cell. Optical microscopy did not allow to differentiate between these Dunaliella strains; however, 18S rDNA fingerprinting methodology allowed us to differentiate D. salina from D. salina/bardawil. CONCLUSION: In Baja Mexico we found D. salina and D. salina/bardawil species by using intron-sizing-method. The National Center for Biotechnology Information (NCBI) Dunaliella 18S rDNA gene sequences were analyzed with our methodology and extraordinary correlation was found with experimental results.