Relationship of Gene-Structure–Antioxidant Ability of Exopolysaccharides Derived from Lactic Acid Bacteria: A Review

Polysaccharides derived from lactic acid bacteria (LAB) have widespread industrial applications owing to their excellent safety profile and numerous biological properties. The antioxidant activity of exopolysaccharides (EPS) offers defense against disease conditions caused by oxidative stress. Several genes and gene clusters are involved in the biosynthesis of EPS and the determination of their structures, which play an important role in modulating their antioxidant ability. Under conditions of oxidative stress, EPS are involved in the activation of the nonenzyme (Keap1-Nrf2-ARE) response pathway and enzyme antioxidant system. The antioxidant activity of EPS is further enhanced by the targeted alteration of their structures, as well as by chemical methods. Enzymatic modification is the most commonly used method, though physical and biomolecular methods are also frequently used. A detailed summary of the biosynthetic processes, antioxidant mechanisms, and modifications of LAB-derived EPS is presented in this paper, and their gene-structure–function relationship has also been explored.