Exploiting synergy of dopamine and stressful conditions in enhancing Haematococcus lacustris biomass and astaxanthin yield

Dopamine (DA) has attracted attention because of its effects on Haematococcus lacustris biomass, astaxanthin production, and physiological responses. The alga treated with 25 μM DA combined with 1 g L–1 sodium chloride exhibited 7.63 %, 41.25 %, and 52.04 % increases in biomass (1.41 g L–1), astaxanthin content (32.37 mg/g), and astaxanthin productivity (3.51 mg L–1 d–1) respectively, compared with the salinity stress and high light. Exogenous DA treatment promoted lipid synthesis while reducing carbohydrate and protein contents. Moreover, carotenogenesis and lipogenesis-associated genes were upregulated under DA induction. Inhibition of reactive oxygen species and autophagy, along with mitogen-activated protein kinase activation, promoted astaxanthin accumulation under DA. Furthermore, DA application boosted astaxanthin biosynthesis by regulating the levels of respiratory metabolic intermediates, the γ-aminobutyric acid shunt, and important phytohormones. These findings present a potential and successful biotechnological approach for enhancing biomass and astaxanthin production in H. lacustris under stressful conditions.