Physiological characterization of Dunaliella sp. (Chlorophyta, Volvocales) from Yucatan, Mexico

Physiological responses of Dunaliella salina and Dunaliella viridis, isolated from solar saltworks on the Yucatan Peninsula, were studied. Optimal growth temperature for D. salina was 22 °C (3.06 × 106 cells mL−1) and 26 °C for D. viridis (4.04 × 106 cells mL−1). Total carotenoid content in D. salina increased with temperature to a maximum of 35.14 pg cell−1 at 38 °C. Dunaliella salina α-carotene and β-carotene content was 0.083 ± 0.003 and 0.598 ± 0.020 mg 100 g dry wt−1 respectively, whereas lower values were found in D. viridis cultured under same experimental conditions (0.018 ± 0.002 and 0.136 ± 0.012 mg 100 g dry wt−1 respectively). The highest specific growth rate in D. salina was obtained at 10% NaCl (0.28 d−1), while its cell volume increased from 524 to 2066.93 μm3 when cultured from 10% to 35% NaCl. Maximum photosynthetic rates were attained when increasing from optimal growing temperature to 30 °C for D. viridis (108 nmol O2 μg chl a h−1) and D. salina (139 nmol O2 μg chl a h−1). Photosynthetic responses to temperature variations indicated physiological adjustments in both species, with higher acclimation in D. salina. Evaluation of physiological attributes of these species will be used for to carry out mass cultivation.