The major lipid changes of some important diet microalgae during the entire growth phase

In the present study, we investigated the major lipid changes of six important diet microalgae (Chlorella sp., Nannochloropsis oculata, Nannochloropsis sp., Isochrysis galbana, Phaeodactylum tricornutum Bohlin and Chaetoceros calcitrans) during the entire growth phase using UPLC-Q-TOF MS system. Our results suggested that EPA/AA-rich lipids were largely detected in both Nannochloropsis sp. and N. oculata as a component of diacylglyceryl-N,N,N-trimethylhomoserine (DGTS). Moreover, docosahexaenoic acids (DHAs) were detected only in I. galbana mainly as a component of monogalactosyldiacylglycerol (MGDG) and sulphoquinovosyldiacylglycerol (SQDG). Besides, the growth phase of microalgae could be a useful variable for the content enrichment of EFA-rich lipids. A higher content EPA/AA-rich DGTS could be obtained at the end of stationary phase for Nannochloropsis sp. and N. oculata, and a higher content of DHA-rich lipids could be obtained at the end of stationary phase for I. galbana. However, EPA/AA-rich lipids were mainly detected in both P. tricornutum and C. calcitrans mainly as a component of TAG and MGDG, respectively. In addition, a higher content of EPA-rich TAG could be obtained at the end of the stationary phase for P. tricornutum. A higher content of EPA-rich MGDG could be obtained at the end of stationary phase for C. calcitrans. Taken together, considering the high EFA requirement for artificial rearing of marine organisms, Nannochloropsis sp., N. oculata, P. tricornutum, C. calcitrans and I. galbana would be highly recommended to be harvested at the end of the stationary phase. The distribution characteristics of EFA-rich lipids related to 6 microalgae are described in detail.