Analysis of phospholipids and neutral lipids in three common northern cold water diatoms: Coscinodiscus concinnus, Porosira glacialis, and Chaetoceros socialis, by ultra-high performance liquid chromatography-mass spectrometry

Three commonly occurring northern marine diatoms, Coscinodiscus concinnus, Porosira glacialis, and Chaetoceros socialis, were cultivated in nutrient replete growth medium and harvested in the exponential growth phase. Cultivation took place at temperatures similar to ambient late spring bloom temperature (7 A degrees C). The lipids were extracted and analyzed by means of ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS). The lipids analyzed in the current study were comprised of the two major groups phospholipids and neutral lipids. The results demonstrated that for both P. glacialis and C. concinnus, the predominant fatty acid identified in the acylglyceride profile was the essential omega-3 fatty acid eicosapentaenoic acid (EPA) that accounted for 28.1 and 15.0% of the total lipids, respectively. In the phospholipid profile of P. glacialis and C. concinnus, EPA constituted 15.2 and 15.0% respectively, of the total lipids. In contrast, C. socialis had a significantly lower EPA content in acylglycerides (only 5.8%), and no EPA was detected in its phospholipid profile.