Analysis of Composition, Antioxidation, and Immunoregulation for Exopolysaccharide Produced by Dellaglioa algida

Lactobacillus is a recognized probiotic and has been widely used in food and medicine. As a new type of low-temperature resistant Lactobacillus, the fermentation products of Dellaglioa algida have multiple physiological activities. This study focuses on the exopolysaccharide (EPS) produced by Dellaglioa algida. The composition of the EPS is analyzed by FTIR, UV, GPC, HPLC, NMR, and SEM, and its antioxidant and immune activities are explored. The experimental results show that the EPS is a polymer composed of nine monosaccharides such as rhamnose, glucose, and mannose, connected by α- and β-glycosidic bonds, with an average molecular weight of 2.163×104 Da. When the EPS concentration reaches 100 μg/mL, the scavenging activities of DPPH and ABTS+ are 60.0% and 51.2%, respectively. The EPS promotes the secretion of NO by regulating the iNOS/NO pathway, reduces oxidative damage, and reduces the secretion of inflammatory factors such as IL-6, IL-1β, and TNF-α, and downregulates the mRNA expression of inflammatory factors, thereby alleviating the cell inflammation stimulated by the cold-resistant bacteria Pseudomonas fluorescens and Pseudomonas fragi. By virtue of these properties, the EPS produced by Dellaglioa algida fermentation has the potential to act as an antioxidant and immunomodulator.