摘要：Salt-induced osmotic pressure has been drawing increasing attention in the field of microalgal biomechanics because it can enhance the lipids accumulation of microalgae.Studies have shown that osmotic stress can affect the synthesis of phospholipids by activating different phospholipid signaling pathways.However,there is little research about the mechanism of action of osmotic stress in neutral lipids synthesis.In this work,the effects of different salt-induced osmotic pressure on oil synthesis and potential mechanismwere studied.First,effect of various salt4nduced osmotic pressure of 64,112,191,453 and 1304 mOsm/kg on Chlorella pyrenoidosa oil synthesis were studied and optimal salt-induced osmotic pressure of 453 mOsm/kg was acquired.Then the content of key signaling chemicals in the Cyclic Adenosine monophosphate(cAMP)signaling pathway and the key enzyme activities in the lipid synthesis pathway were determined under salt-induced osmotic pressure of 453 mOsm/kg.It was found that the cAMP signaling pathway were up-regulated under salt osmotic pressure conditions of 453 mOsm/kg;in addition,the key enzymes related to lipid synthesis increased,while those related to protein synthesis decreased,enabling the increase of the lipid content.Finally,the effects of inhibitor atropine and promoter IBMX of cAMP signal pathway were also investigated.Results showed that atropine inhibits the cAMP signaling pathway and the lipid contents decreased;in contrast,IBMX activated thecAMP signaling pathway and the lipids content increased.These observations further confirm that salt-induced osmotic pressure had the same function as the signal promoter to regulate lipid synthesis by adjusting cAMP signaling pathway regulating lipid synthesis.This study preliminarily revealed the mechanism that salt-induced osmotic pressure affected lipid synthesis pathway through cAMP signaling pathway to regulate lipid synthesis in microalgae.

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