Effects of Salt Concentrations and Nitrogen and Phosphorus Starvations on Neutral Lipid Contents in the Green Microalga Dunaliella tertiolecta

Abstract

Dunaliella tertiolecta, a halotolerant alga, can accumulate large amounts of neutral lipid, which makes it a potential biodiesel feedstock. In this study, neutral lipids of D. tertiolecta induced by different salinities or N or P starvation were analyzed by thin-layer chromatography (TLC), flow cytometry (FCM), and confocal laser scanning microscopy (CLSM). High salinities or N or P starvation resulted in a decrease in cell growth and chlorophyll contents of D. tertiolecta. Neutral lipid contents increased markedly after 3-7 days of N starvation or at low NaCl concentrations (0.5-2.0 M). N starvation had a more dramatic effect on the neutral lipid contents of D. tertiolecta than P starvation. Four putative ME isozymes in different conditions can be detected by using isozyme electrophoresis. Two alternative acetyl-CoA producers, ACL and ACS genes, were up-regulated under low salinities and N starvation. It was suggested that low salinities and N starvation are considered efficient ways to stimulate lipid accumulation in D. tertiolecta.</p