Margot Bligh1,2, Nicola Steinke2, Mohammad Shahin1, Inga Hellige1,2, Hagen Buck-Wiese1,2, Manuel Liebeke1, Jan-Hendrik Hehemann1,2
1Max Planck Institute for Marine Microbiology, Bremen, Germany
2MARUM Centre for Marine Environmental Sciences, University of Bremen, Bremen, Germany
Carbon dioxide fixation to glycans by macroalgae is proposed to be a major pathway for carbon sequestration. Complex, anionic glycans secreted by brown algae called fucoidans persist in the environment and assemble into microgels that promote aggregation of large particles, leading to carbon export and sequestration. The complexity and variability of fucoidans has so far challenged our ability to separate and analyse these glycans in the environment. We aim to develop a pipeline based on non-enzymatic hydrolysis and mass spectrometry for high resolution identification of fucoidans in the marine environment. Our preliminary results using this pipeline demonstrate the ability to distinguish fucoidans from different species based on their unique oligosaccharide profiles. Fucoidans were bought or purified from biomass of Fucus vesiculosus, Sargassum fluitans, Lessonia trabeculata and Ecklonia maxima using a combination of autoclaving, filtration, enzymatic digestion and chromatography techniques. Purified fucoidans yielded oligosaccharide fingerprints from oxidative cleavage using the Fenton’s initiation toward defined oligosaccharide groups (FITDOG) method (Amicucci et al., 2020). The fucoidans differed in their oligosaccharide profiles in liquid chromatography mass spectrometry, with some features unique to a species’ fucoidan and other features distinct in their relative abundances. These reproducible features enable species-specific fucoidan recognition. Application of this method to environmental samples of dissolved and particulate organic matter in the future will allow us to track fucoidan through the marine carbon cycle with high specificity, delineating the contributions of different algae to various pathways for carbon sequestration.