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Abstract

Comparative metabolomics is an emerging technique suitable for the monitoring of metabolic responses of organisms to external stimuli or stress factors like biotic interaction partners, nutrient limitation or adverse environmental conditions. Using data from comparative metabolomics, changes in primary metabolism can be unraveled and connected to the regulation of metabolic pathways. However, the technique is also suitable for an untargeted screening of primary and secondary metabolites. Thereby candidate metabolites can be identified that might play a functional role in the particular stress situation. Especially mass spectrometry-enabled techniques have found their way into many disciplines. Here we describe the extraction, derivatization, gas chromatography-mass spectrometry (GC-MS) as well as liquid chromatography-mass spectrometry (LC-MS) measurement and data analysis for a metabolic profiling of algae. We describe a general protocol for intracellular profiling of microalgae, and germ cells and thalli of macroalgae. The protocol outlines the procedure to extract, derivatize and measure the exo-metabolome of these organisms, i.e., the metabolites exuded into the seawater.
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The method was initially developed for metabolomics of the diatom Skeletonema marinoi but proved to be suitable for a broad range of micro- and macroalgae after minor adaptations. The entire work-flow can be carried out in laboratories with basic equipment for chemical work and measurements can be recorded on most commercially available GC-MS and LC-MS systems.