A novel viscous hydrophilic colloidal polysaccharide produced by Lactiplantibacillus plantarum T1: Structural characterization, rheological behavior and biological activity

Lactic acid bacteria exopolysaccharide (EPS) with viscosity and biological activities has huge potential applications in functional fermented foods. In this study, an EPS (EPS-T1) with high molecular weight (1.41 ×106 Da) was isolated and purified from the Lactiplantibacillus plantarum T1, which was composed of glucose, galactose at a molar ratio of 1.21: 1.00. Through the size-exclusion chromatography and multi-angle laser light scattering (SEC-MALLS) analysis, the intrinsic viscosity [η] and hydrodynamic radius (Rh) of EPS-T1 were calculated to be 458.1 mL/g and 45.4 nm, respectively, which showed a flexible chain conformation. Rheological properties showed that EPS-T1 was a typical pseudoplastic fluid with high viscosity and weak gel performance, and which can be adjusted by the conditions of temperature, pH value and saline ions. Meanwhile, the in vitro immunomodulatory assays presented that it could induced the secretion of nitrous oxide, cytokines (IL-1β, TNF-α, IL-6 and IL-10) and significantly enhanced the pinocytic and phagocytic activities of macrophages. This work provides some basis for the functional applications of EPS-T1 from the Lactiplantibacillus plantarum T1.