Chemical and enzymatic hydrolysis of alginate: a review

Alginate is a brown seaweed-based linear polysaccharide of D - mannuronic acid and L - guluronic acid residues. Hydrolysis products of the polysaccharide, specifically oligosaccharides, have been receiving increasing interest, due to their significant bioactivity and potential utilisation routes. The bioactivity of alginate oligosaccharides is closely linked to structural characteristics, namely: molecular weight, degree of polymerisation, and ratio of the monomers (the M/G ratio). Hence, potential applications (such as utilisation as a biostimulant fertilizer) depend on these parameters. This review focuses on recent advances in producing alginate oligosaccharides using chemical or enzymatic methods. The literature survey includes utilisation of these methods at both laboratory and industrial scale. For the chemical methods, we assessed the standard laboratory scale procedures of alginate oligosaccharide production, the potential of scaling up to an industrial level, and the subsequent challenges. For the enzymatic route, we provide an overview of alginate lyases and the application perspectives of enzymatic hydrolysis of alginate.