Effect of pH, light intensity, salt and nitrogen concentrations on growth and β-carotene accumulation by a new isolate of Dunaliella sp

In the present study Dunaliella sp. that could grow in the Johnson medium was isolated from hypersaline Lake Tuz and its beta-carotene production was studied in a batch system, in order to determine the optimal conditions required for the highest beta-carotene accumulation. In the experiments with light intensity, the cell numbers and beta-carotene content were maximum at pH 9, with 20% of NaCl concentration and 48 kerg cm(-2) s(-1) light intensity. At this light intensity, the beta-carotene content of Dunaliella sp. ranged between 0.177 and 1.095 mg/ml for the culture broth and 0.119 to 0.261 ng/cell on a per cell basis under the nitrogen limitation. At the end of the experiments, the maximum beta-carotene accumulation and the cell number were obtained at pH 7, 5 mM NaNO3 and 20% NaCl concentrations as 0.261 ng/cell, 4.2x10(6) cell/ml, respectively.