Production of biomass and carotenoids of Dunaliella tertiolecta in nitrogen-limited cultures

Microalgae have a high content of antioxidant compounds (carotenoids, phycobilins and fatty acids) used in biotechnology industry. Under stress conditions Dunaliella cells produce more carotenoids. Because of this, we evaluated growth, biomass and carotenoid production under control (indoor) and outdoor conditions using mass cultures of Dunaliella tertiolecta Butcher, under nitrogen-limited media. Control medium was f/2 (nitrates: 18.75 g/L), and limited media were f/4 (nitrates: 37.5 g/L), f/6 (nitrates: 25 g/L) and f/8 (nitrates: 18.75 g/L). The highest cell concentrations were found in cultures using medium f/2 maintained indoor (1.28 x 10(6) cells/mL) and outdoor (0.76 x 10(6) cell/mL). Dry biomass increased in both culture conditions when nitrogen decreased in the medium (Indoor: 100 to 217 pg/cell, and Outdoor: 230 to 355 pg/cell). The highest concentration of total carotenoids was found using medium f/8 whereas the highest productivity was obtained using medium f/2 achieving yields of 0.03 mg/L of zeaxanthin, 9.19 mg/L lutein, 19.56 mg/L chlorophyll b, 1.62 mg/L chlorophyll a and 5.40 mg/L beta-carotenoids. In conclusion, carotenoid concentration increased in nitrogen-limited cultures, but cell density decreased under such conditions.