A novel exopolysaccharide-producing bacterium from traditional rice wine koji in China: Whole genome sequencing, exopolysaccharide isolation and bio-functional properties assessment

An exopolysaccharide (EPS)-producing bacterium, identified as Weissella cibaria based on 16S rDNA sequencing, was isolated from Chinese traditional rice wine koji. Whole-genome sequencing (WGS) revealed 2261 core genes and 3 plasmids, with 95 carbohydrate-active enzymes identified in the genome. The EPS produced by W. cibaria ZJU.1 was primarily composed of glucose, with a molecular weight of 144.5 kDa, as determined by highperformance anion-exchange chromatography (HPAEC) and high-performance gel chromatography (HPGPC). Structural analysis indicated that the EPS predominantly consists of alpha-(1-* 6) glycosidic bonds (88.32%) and alpha-(1-* 3) branches (11.68%). Microscopic examination revealed an interleaved fibrous structure at low concentrations and a lamellar structure at higher concentrations. Thermal analysis demonstrated good stability, with the carbon ring structure intact up to 264.12 degrees C. Furthermore, the EPS exhibited excellent dispersion stability and rheological properties at higher concentrations. Activity prediction using a zebrafish model suggested potential therapeutic benefits, including alleviation of diabetes, anti-tumor, and anti-epileptic effects. This study highlights the promising food and pharmaceutical applications of W. cibaria ZJU.1 EPS.