Transcriptome and metabolome analysis reveals the salt stress-response mechanism in desert isolated Chlorella sp. DT025

Understanding salt stress-response mechanisms is beneficial for biodiesel production using microalgae. Herein, using physiological and multi-omics analyses, we revealed substance changes and the salt-stress response of Chlorella sp. DT025, isolated from a desert salt marsh. Using 15–30 g/L NaCl, high biomass (4.1–2.6 g/L) and high lipid content (45–65 %) were obtained. Under salt stress, the levels of chlorophyll synthesis-, photosynthesis-, Calvin cycle-, and starch synthesis-related differentially expressed genes (DEGs) were downregulated, while the contents of chlorophyll, most amino acids and nucleotides were decreased. Moreover, the levels of TCA cycle-, fatty acid (FA) synthesis and degradation-, glycerophospholipid metabolism-, nitrogen metabolism-, proline synthesis-, and antioxidant metabolism-related DEGs were upregulated, increasing FAs (major 16- and 18- carbon FAs), phosphatidylglycerol, lysophosphatidylglycerol, digalactosyldiacylglycerol, proline, catalase, and superoxide. These results reveal the molecular basis of salt tolerance in DT025 and suggest that it exhibits active metabolism using lipids as substances for energy storage and release under salt stress.