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L. Reisky, A. Prechoux, M. Zühlke, M. Bäumgen, C. Robb, N. Gerlach, T. Roret, C. Stanetty, R. Larocque, M. Gurvan, T. Song, S. Markert, F. Unfried, M.D. Mihovilovic, A. Trautwein-Schult, D. Becher, T. Schweder, U. Bornscheuer, J. Hehemann:
"A marine bacterial enzymatic cascade degrades the algal polysaccharide ulvan";
Nature Chemical Biology, 15 (2019), S. 803 - 812.

Marine seaweeds increasingly grow into extensive algal blooms, which are detrimental to coastal ecosystems, tourism and aquaculture. However, algal biomass is also emerging as a sustainable raw material for the bioeconomy. The potential exploitation of algae is hindered by our limited knowledge of the microbial pathways-and hence the distinct biochemical functions of the enzymes involved-that convert algal polysaccharides into oligo- and monosaccharides. Understanding these processes would be essential, however, for applications such as the fermentation of algal biomass into bioethanol or other value-added compounds. Here, we describe the metabolic pathway that enables the marine flavobacterium Formosa agariphila to degrade ulvan, the main cell wall polysaccharide of bloom-forming Ulva species. The pathway involves 12 biochemically characterized carbohydrate-active enzymes, including two polysaccharide lyases, three sulfatases and seven glycoside hydrolases that sequentially break down ulvan into fermentable monosaccharides. This way, the enzymes turn a previously unexploited renewable into a valuable and ecologically sustainable bioresource.

http://dx.doi.org/10.1038/s41589-019-0311-9