Identification and characterization of <italic>Dunaliella salina</italic> OH214 strain newly isolated from a saltpan in Korea

Abstract

Carotenoids are effective antioxidants that are found in various photosynthetic organisms. Marine microalgae are an advantageous bioresource for carotenoid production because they do not compete with other crops for freshwater and arable land. This study reports a newly isolated Dunaliella strain from the Geumhong Saltpan on Yeongjong Island, West Sea, Korea. The new strain was isolated and classified as Dunaliella salina through phylogenetic analysis and was named the OH214 strain (Deposit ID: KCTC14434BP). The newly isolated strain can survive in a wide range of NaCl concentrations (0.3−5.0 M NaCl), but grows well in 0.6 to 1.5 M NaCl culture medium. Under high-light conditions (500 ± 10 μmol photons m<sup>-2</sup> s<sup>-1</sup>), the cells accumulated three times more β-carotene than under low-light conditions (50 ± 5 μmol photons m<sup>-2</sup> s<sup>-1</sup>). The cells accumulated 2.5-fold more β-carotene under nitrogen-deficient (1 mM KNO<sub>3</sub>) conditions (3.24 ± 0.36 μg 106 cells<sup>-1</sup>) than in nitrogen-sufficient conditions (>5 mM KNO<sub>3</sub>). The lutein content under nitrogen-deficient conditions (1.73 ± 0.09 μg 106 cells<sup>-1</sup>) was more than 24% higher than that under nitrogen-sufficient conditions. Under the optimized culture condition for carotenoid induction using natural seawater, D. salina OH214 strain produced 7.97 ± 0.09 mg g DCW<sup>-1</sup> of β-carotene and 4.65 ± 0.18 mg g DCW<sup>-1</sup> of lutein, respectively. We propose that this new microalga is a promising strain for the simultaneous production of β-carotene and lutein.