Marine Sugars and the Carbon Cycle

marine secuestration

Polysaccharides — long chains of sugar molecules — are a major source of energy in the ocean. Every year, algae carry out around half of the world’s photosynthesis, turning carbon dioxide into a wide variety of these sugars, known as glycans.

Each glycan has a unique structure, which determines how it behaves and moves through marine ecosystems.

We study complex sulfated polysaccharides made by algae and released into the ocean. These sugars are hard for marine bacteria to break down, often requiring special enzymes. Sometimes, the glycans escape digestion entirely — they clump together, sink to the deep sea, and trap carbon for hundreds of years. They also have interesting biological effects and are being explored for use in medicine and skincare.

One of the big questions we're working on is: which sugar structures lead to these effects? Right now, we still don’t fully understand how specific polysaccharide shapes are linked to carbon storage or health benefits — and we aim to change that.

Selected Publications

  1. Crawford, C. J. et al. Activity-based FRET detection of glycan turnover in microbiomes.ChemRxiv (2025).https://doi.org/10.26434/CHEMRXIV-2025-7GLD3
  2. Crawford, C. J. et al. Automated Synthesis of Algal Fucoidan Oligosaccharides.J Am Chem Soc 13, 39 (2024).
  3. Krull, J. et al. Polyelectrolyte mannan from diatoms reshapes sunlit ocean microbiome.BioRxiv (2024).https://doi.org/10.1101/2024.07.03.601839
  4. Solanki, V. et al. Glycoside hydrolase from the GH76 family indicates that marine Salegentibacter sp. Hel_I_6 consumes alpha-mannan from fungi.ISME J 16, 1818–1830 (2022).
  5. Buck-Wiese, H. et al. Fucoid brown algae inject fucoidan carbon into the ocean.Proc Natl Acad Sci U S A 120, e2210561119 (2023).
  6. Sichert, A. et al. Verrucomicrobia use hundreds of enzymes to digest the algal polysaccharide fucoidan.Nat. Microbiol 5, 1026–1039 (2020).