Growth, bioactive compounds and chemical composition of marine microalga Dunaliella salina in batch cultures

Abstract

Because microalgae contain a wide variety of chemical and bioactive components that can be used to feed animals, especially aquaculture species, the present study aimed to evaluate the growth, bioactive compounds and chemical composition of the marine microalga Dunaliella salina in two batch cultures: autotrophic (saline) or mixotrophic (Conway). Thus, growth curve, cell diameter, growth rate (k), productivity (mg/L/day), maximum cell density (MCD), and chemical composition were evaluated through the macro and micronutrients and bioactive compounds. The D. salina in mixotrophic Conway medium had an earlier exponential phase and higher MCD (23,500 cells/ml), productivity, and growth rate (P < 0.05) than autotrophic saline medium (18,200 cells/ml), although the cell diameter of D. salina was greater (P < 0.05) in autotrophic (25.5 μm ± 2.65) than in mixotrophic medium (21.25 μm ± 1.26). The biomass of D. salina in mixotrophic medium obtained greater values (P < 0.05) of protein (60.43%), nitrogen (9.67 mg/g), and chlorophyll a (60.60 mg/L), whereas autotrophic medium provided greater values of lipids (6.93%), sugars (8.09%), gross energy (3955 kcal/kg), phosphorus (8.40 mg/g), potassium (128.66 mg/g), magnesium (29.23 mg/g), zinc (8.23 mg/g), total carotenoids (34.73 mg/L), vitamin C (87 mg/100g), total polyphenols (81.00 mg/100 g), anthocyanins (30 mg/kg), and yellow flavonoids (45.30 mg/100g). The use of the autotrophic saline medium for the D. salina microalgae was a viable alternative to the mixotrophic Conway medium. Due to its nutritional value and bioactive compound profile, D. salina microalgae biomass can be destined to animal and human nutrition.