Diatom fucan polysaccharide precipitates carbon during algal blooms.

Vidal-Melgosa, Silvia; Sichert, Andreas; Francis, T. Ben; Bartosik, Daniel; Niggemann, Jutta; Wichels, Antje; Willats, William G. T.; Fuchs, Bernhard M.; Teeling, Hanno; Becher, Dörte; Schweder, Thomas; Amann, Rudolf; Hehemann, Jan-Hendrik

The formation of sinking particles in the ocean, which promote carbon sequestration into deeper water and sediments, involves algal polysaccharides acting as an adhesive, binding together molecules, cells and minerals. These as yet unidentified adhesive polysaccharides must resist degradation by bacterial enzymes or else they dissolve and particles disassemble before exporting carbon. Here, using monoclonal antibodies as analytical tools, we trace the abundance of 27 polysaccharide epitopes in dissolved and particulate organic matter during a series of diatom blooms in the North Sea, and discover a fucose-containing sulphated polysaccharide (FCSP) that resists enzymatic degradation, accumulates and aggregates. Previously only known as a macroalgal polysaccharide, we find FCSP to be secreted by several globally abundant diatom species including the genera Chaetoceros and Thalassiosira. These findings provide evidence for a novel polysaccharide candidate to contribute to carbon sequestration in the ocean. The fate of ocean carbon is determined by the balance between primary productivity and heterotrophic breakdown of that photosynthate. Here the authors show that diatoms produce a polysaccharide that resists bacterial degradation, accumulates, aggregates and stores carbon during spring blooms.

DISSOLVED organic matter; BACTERIAL enzymes; CARBON sequestration; NAVICULA; MONOCLONAL antibodies; DIATOMS

Nature Communications, 2021, Vol 12, Issue 1, p1

2041-1723

Academic Journal

10.1038/s41467-021-21009-6