Exopolysaccharides enriched in rare sugars: bacterial sources, production, and applications

TLDR

Microbial extracellular polysaccharides (EPS) are diverse high‑molecular‑weight biopolymers whose composition varies widely, and some contain rare sugars such as rhamnose or fucose that can confer additional biological properties. This review surveys EPS enriched in rare sugars and the bacteria that produce them. It summarizes how cultivation conditions influence EPS composition and outlines downstream processing strategies. The review discusses applications of these rare‑sugar EPS in cosmetics, food, pharmaceuticals, and biomedical products.

Abstract

Microbial extracellular polysaccharides (EPS), produced by a wide range of bacteria, are high molecular weight biopolymers, presenting an extreme diversity in terms of chemical structure and composition. They may be used in many applications, depending on their chemical and physical properties. A rather unexplored aspect is the presence of rare sugars in the composition of some EPS. Rare sugars, such as rhamnose or fucose, may provide EPS with additional biological properties compared to those composed of more common sugar monomers. This review gives a brief overview of these specific EPS and their producing bacteria. Cultivation conditions are summarized, demonstrating their impact on the EPS composition, together with downstream processing. Finally, their use in different areas, including cosmetics, food products, pharmaceuticals, and biomedical applications, are discussed.