Identification And Metabolomic Analysis Of Chemical Modulators For Lipid Accumulation In Crypthecodinium Cohnii

The microalgae Crypthecodinium cohnii growing in heterotrophic condition is known for its ability to accumulate lipids with a high fraction(30–50%) of DHA. This property makes the C. cohnii fermentation process economically more competitive to other major DHA sources.In the study, fourteen chemical modulators from five groups(i.e., auxin, gibberellin, cytokinin, signal transducer and amine) were evaluated for their effects on lipid accumulation in C.cohnii. The results showed that naphthoxyacetic acid(BNOA), 2-chlorodracylicacid, salicylic acid(SA), abscisic acid(ABA) and ethanolamine(ETA), increased lipid accumulation in C. cohnii by 10.00-18.78%.As chemicals from the different groups may have different stimulatory mechanisms, a combined application of these chemicals was expected to have cumulative effects. To evaluate this hypothesis, 1:1(v/v) combinations of the above four chemicals were made and tested their effects on lipid accumulation, with chemicals added separately as controls. The result showed that two combinations, 1.0 mg/L BNOA & 2.5 m M ETA and 4.0 mg/L SA & 2.5 mM ETA, increased lipid accumulation by 20.54% and 22.45%, respectively.Moreover, a targeted metabolomic approach was employed to decipher the possible mechanisms responsible for the increased lipid accumulation, and the results showed that the enhanced metabolism in glycolysis and TCA cycle as well as the decreased metabolism in PPP pathway could be important for the stimulatory roles of BNOA & ETA and SA & ETA on lipid accumulation in C. cohnii.