Microscopic and Molecular Insights into Heterogeneous Phase Degradation of Agars and Carrageenans by Marine Bacterial Galactanases

Agars and carrageenans are sulfated galactans and are the main matrix component of the cell wall of red algae. They form gels made of a 3D network of fibres built by the aggregation of polysaccharide double-helices. Agarases and carrageenase are enzymes produced by marine bacteria involved in the conversion of algal biomass. We have analyzed the structures and the modes of action of these enzymes adapted to the degradation of anionic polysaccharides in heterogeneous phase. We found that κ- and ι-carrageenases proceed via an endo-processive mode of action as it was already described for other enzymes active on neutral polysaccharides (cellulose, starch).