TAG Analysis In Microalgae By LC-MS

The method of analyzing TAG in microalgae was established using Ultra Performance LiquidChromatography-Electrospray ionization-Quadrupole-Time of Flight Mass Spectrometry(UPLC-ESI-Q-TOF-MS). The mass spectrometry was performed in reflective time-of-flight using electronspraying ionization in positive mode. Characteristic fragment ions as lithiated adducts can be used toestablish elemental composition and acyl composition of TAG. The signal intensity of the fragment ionsused to determined the positional distribution of the fatty acyl chains (sn-1/3vs sn-2). Based on thefragmentation patterns discussed above, many types of major TAGs were identified for the first time inthese diatoms, the results highlighted the potential advantages of diatom as biofuel production. There are16TAGs in N. f. minutissima and total TAG contents793.2±32.51nmol mg-1total lipids. N. f. minutissimawere chosen as the most promise biofuel-production organisms based on criteria such as high abundance ofTAGs yields containing C16:1by comparing the individual species. Additionally, based on theinformation of sn-2fatty acid obtained so forth (mainly C16in sn-2position), we put forward ahypothesis that TAGs in diatoms are mainly derived from lipids in chloroplasts through prokaryoticbiosynthesis pathway.The TAG and other lipid composition of microalgae can been used as a general chemotaxonomicguide to characterize microalgal classes, especially those indistinguishable by molecular analyses andultrastructural characters. We have characterized the lipidomics difference of Nannochloropsis oculata andNannochloropsis sp., which are morphologically similar. The analyses of N. oculata and Nannochloropsissp. have been completed by PCA and OPLS-DA. This technique can become an interesting section ofmicroalgae systematics as a valid chemotaxonomic tool.The composition of PUFA-rich lipid were important for larval shellfish nutrition, for example:20:5(EPA),22:6(DHA) and20:4(AA), the nutrition study of diet microalgae has broad commercial andecological significance. Due to different lipid compositions, marine microalgae can vary in their nutritionalvalue compared with a variety of planktivorous animals. Our data provided a useful nutrient database for the screening of appropriate diet microalgae in artificial rearing of shellfish. Taken together, considering theshellfish nutrition for human health, Nannochloropsis sp., N. oculata, P. tricornutum Bohlin, C.calcitrans and I. galbana would be highly recommended to harvest all at the end of stationary phase forshellfish culture.