Phosphorus and sulphur affecting the growth, nutrient uptake and amino acids composition in Dunaliella salina

The potential of microalga Dunaliella salina as a protein source and in bioremediation application is still underdeveloped, despite its known carotenoids overproduction. This study focused on investigating the effects of phosphorus (P) and sulphur (S) concentrations on the biomass growth and essential amino acids profile of D. salina PLY DF15 (CCAP 19/41). Additionally, its nutrient removal capacity was analysed in a bioremediation context. From all tested P and S concentrations, D. salina resulted in high-quality protein with essential amino acid index (EAAI) between 1.6 and 1.7 (EAAI ≥ 1 meets FAO/WHO standard) with little variations from all P and S concentrations. In a bioremediation context, D. salina also showed great potential for nutrients removal and recovery with high adaptability to varying nutrient conditions, with overall more than 80 % and 100 % nitrogen (N) and P recovery, respectively. The full recovery of S however was only achieved at lower S levels. Overall D. salina shows great potential in providing high-quality protein for human consumption using economic and sustainable cultivation approach. • Both high and low phosphorus (P) and sulphur (S) levels hinder the biomass growth. • D. salina produces high-quality protein for human consumption. • Phosphorus and sulphur do not affect essential amino acid profile and index. • D. salina can remove and recover all P, S and nitrogen (N) to significant levels.