Microbial enzymes display sophisticated mechanisms to depolymerize industrially relevant algal polysaccharides

Polysaccharides from marine algae have many different bioactivities and industrially relevant applications that result from their chemically unique structures. Charged polysaccharides such as fucoidan, carrageenan, and alginate are of particular interest, as they are readily abundant, show a strong influence on the marine carbon cycle and demonstrate particular industrial potential. Currently, the controlled generation of oligosaccharide products from these polysaccharides remains a hurdle. A promising solution to this is by the use of microbial enzymes that selectively target unique algal polysaccharides and depolymerize or modify them into useable products. To effectively incorporate these enzymes into a growing collection of biocatalysts, the mechanisms they employ to facilitate highly specific recognition and processing of distinct polysaccharides must be elucidated. Accordingly, this review discusses several significant advancements recently made in the structural analysis of microbial enzymes that efficiently depolymerize fucoidan, carrageenan, and alginate.