Structural characterization of exopolysaccharide from Lacticaseibacillus rhamnosus and its protective mechanism against dyslipidemia in obese mice

Obesity is a complex metabolic disorder, and its treatment remains ongoing challenges worldwide. Exopolysaccharides (EPS) produced by lactic acid bacteria are increasingly recognized as potential prebiotics for combating obesity. This study purified EPS2 from L. rhamnosus LR-ZB1107-01 and revealed it as a heteropolysaccharide (Mw 8.42 × 10 4  Da) with 92.5% mannose and 7.43% glucose in molar composition. EPS2 featured a backbone of alternating →2)-α-D- Man p -(1→ and →2,6)-α-D-Man p -(1→ glycosidic linkages, with side chains consisting of α-D-Man p -(1→ units attached at the O-6 positions of the latter residues. In vivo tests demonstrated that EPS2 effectively alleviated obesity-related symptoms, ameliorated dyslipidemia, and inhibited hepatic oxidative damage and lipid deposition. Additionally, EPS2 modulated gut microbiota composition, increasing the abundances of beneficial genera such as Parabacteroides and Candidatus Saccharimonas strongly linked to the alterations in fecal metabolites like arterolane and glycerol tributanoate. The potential of EPS2 in obesity treatment through gut microbiota regulation and metabolic reprogramming provided new insights for the development of anti-obesity strategies.