Implementation in lipid extraction and analysis from phytoplankton: Skeletonema marinoi as case study

Microalgae, dominating protists in aquatic systems, are rich in lipids, a complex molecular class regulating cell physiology and phytoplankton ecology. Investigation of microalgal lipid metabolism is increasing, but common strategies for comprehensive lipid analyses are still lacking. Major methodological gaps are represented by separate analytical procedures for extraction and characterization of lipid molecules, thus hindering accurate comparison of metabolic data. Herein we propose one unique methodology for sample collection, extraction and analysis of main lipid mediators (oxylipins, fatty acids, glycerolipids, sterols and sterol derivatives) from diatoms. Extractions relied on the MTBE/methanol method, which provides high lipid extraction yields, involving either MeOH or water preparation of samples. Experiments focused on Skeletonema marinoi, a diatom species often used as model organism in plankton chemical ecology. Extraction protocols were implemented to characterize oxylipins and glycerolipids from algal cells collected as pellets or accumulated on glass-fibre filters, thus providing a practical tool to study multiple lipid classes in natural phytoplankton.