Exploiting Enzymatic Machineries of Bacteria to Resolve Marine Polysaccharide Turnover

• Applicant: Professor Dr. Jan-Hendrik Hehemann
• Subject Area: Microbial Ecology and Applied Microbiology ; Biochemistry
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 259266681

• Final Report Year: 2021

Final Report Abstract

Polysaccharides of marine, photosynthetic algae are bioenergy and carbon for various heterotrophs including bacteria and larger organisms. Polysaccharides account for over 50% of the carbon dioxide fixed by photosynthesis. However, the quantity and types of polysaccharides that are synthesized by algae in the Ocean remain unknown due to analytic challenges associated with this class of macromolecules. This project develops new technologies to measure polysaccharides in seawater with the aim to better constrain the numbers concerning their production, turnover and sequestration. To achieve this we develop biocatalytic assays that are based on enzymes that marine bacteria use to degrade and consume the polysaccharides. The enzymes function like restriction enzymes in DNA analysis and provide glycan specific fingerprints that can be more easily quantified. We also use antibody detection of algal polysaccharides to identify low concentrations of polysaccharides in marine organic matter. Finally, we explore the polysaccharide sensing apparatus of bacteria with proteomics to evaluate their potential as biosensors for these molecules. Using these complementary approaches we have recently quantified the algal beta-glucan laminarin throughout the Atlantic and in the Pacific and found that it accounts for an estimated annual production of 18±9 gigatons. This molecule makes up about 1/3 of the marine and 1/5 of the global primary production. Therefore, within this Emmy Noether project we revealed that laminarin is a central bioenergy molecule in Earth’s carbon cycle. We also used antibody-based technology during algal spring blooms and found polysaccharides that accumulated over time and were not degraded by bacteria. This recalcitrance suggests that polysaccharides may constitute a previously unidentified carbon sink in the Ocean.

Publications

• A marine bacterial enzymatic cascade degrades the algal polysaccharide ulvan. Nat Chem Biol 15, 803
  Reisky, L., Prechoux, A., Zuhlke, M. K., Baumgen, M., Robb, C. S., Gerlach, N., Roret, T., Stanetty, C., Larocque, R., Michel, G., Song, T., Markert, S., Unfried, F., Mihovilovic, M. D., Trautwein-Schult, A., Becher, D., Schweder, T., Bornscheuer, U. T. & Hehemann, J. H.
  
• 2020. Verrucomicrobia use hundreds of enzymes to digest the algal polysaccharide fucoidan. Nature Microbiology:1- 14
  Sichert A, Corzett CH, Schechter MS, Unfried F, Markert S, Becher D, Fernandez-Guerra A, Liebeke M, Schweder T, Polz MF, Hehemann, JH
  
• Laminarin is a major molecule in the marine carbon cycle. Proceedings of the National Academy of Sciences 117, 6599-6607 (2020)
  Becker, S., Tebben, J., Coffinet, S., Wiltshire, K., Iversen, M. H., Harder, T., Hinrichs, K.- U. & Hehemann, J.-H.
  
• Diatom fucan polysaccharide precipitates carbon during algal blooms. Nat Commun 12, 1150
  Vidal-Melgosa, S., Sichert, A., Francis, T. B., Bartosik, D., Niggemann, J., Wichels, A., Willats, W. G. T., Fuchs, B. M., Teeling, H., Becher, D., Schweder, T., Amann, R. & Hehemann, J. H.
  
• Enigmatic persistence of dissolved organic matter in the ocean. Nature Reviews Earth & Environment 2, 570-583
  Dittmar, T., Lennartz, S. T., Buck-Wiese, H., Hansell, D. A., Santinelli, C., Vanni, C., Blasius, B. & Hehemann, J.-H.
  
• Secretion of sulfated fucans by diatoms may contribute to marine aggregate formation. Limnology & Oceanography
  Huang, G., Vidal-Melgosa, S., Sichert, A., Becker, S., Fang, Y., Niggemann, J., Iversen, M. H., Cao, Y. & Hehemann, J.-H.