Growth, lipids, proteins, and carotenoid contents of some freshwater green microalgae under simulated day/night temperature fluctuation

Abstract

Day/night or seasonal temperature fluctuation is a major factor during outdoor cultivation of microalgae. In the present study, we investigated the impact of simulated day/night temperatures (20^oC night and 30^oC day) on the growth, lipid, protein and carotenoid contents of four local oleaginous microalgae strains under mixotrophic and heterotrophic conditions. The impact of simulated day/night temperatures on the growth and biochemical compositions varied across species and culture conditions (mixotrophic or heterotrophic). The lipid productivity by Dictyosphaerium sp. under heterotrophic condition was twice the value obtained at constant temperature but showed no significant (p > 0.05) impact under mixotrophic condition. Desmodesmus subspicatus elicited higher lipid (15%) and carotenoid (56%) contents under simulated day/night temperature regime than at constant temperature (30^oC) (p<0.05). There was a negative impact on the protein content of the microalgal species under mixotrophic and heterotrophic conditions. The above results have shown that these species have high potentials for co-production of lipids, protein and carotenoid under outdoor conditions.