Degradation pathway of Green algal polysaccharide ulvan

Marine macroalgal species have gained considerable global attention as source of renewable biomass. Among the three main divisions of macroalgae, red, brown, and green algae, green algae remain largely unexploited. As a consequence of the strong environmental impact of these green seaweeds, the interest in exploiting such natural resource has increased significantly, especially for its long chain polymer part, ulvan. The main constituents of ulvan are 3-sulfated rhamnose (Rha3S), D-glucuronic acid (GlcA), L-iduronic acid (IdoA), and D-xylose (Xyl). The repetition moieties are disaccharides composed of Rha3S linked with GlcA or IdoA, termed ulvanobiuronic acid A or B, respectively, or xylose in lower amounts. Conversion from polymers into fermentable oligomers requires chemical or biological break down. However, the process of chemical conversion could be very expensive and not be worthwhile to use for an economical large-scale production. The enzymatic hydrolysis has been suggested as a more environmentally and economically treatment due to the low energy requirement, less byproduct production. Thus, discovery of new enzymes for ulvan degradation becomes a key step for better managing and utilizing this resource.