Concomitant effects of light and temperature diel variations on the growth rate and lipid production of Dunaliella salina

The microalgae Dunaliella salina has the capacity to grow in salterns at high salinity. In this particular shallow environment, D. salina is exposed to strong light and temperature variations and has developed various strategies such as cell cycle adaptation and storage of dedicated metabolites. The effects of light/dark cycles have already been studied, but few works focused on the concomitant effects of light and temperature variations characterizing salterns and outdoor conditions. In this study, growth, carbon and nitrogen storage, pigments and lipid production of D. Salina were measured in laboratory conditions mimicking the outdoor light and temperature conditions. A control experiment with constant temperature was carried out with light variations only. During the night, cell respiration was correlated with temperature, following an Arrhenius law. Many differences with the control at constant temperature confirmed that temperature variations are a crucial parameter in outdoor conditions and should be taken into account to predict growth. Triglyceride and pigment production was tightly linked to the light dark cycle.