Extraction of polysaccharides from waste medium as functional ingredients

The post-fermentation culture medium, an underutilized resource, contains substantial amounts of bioactive polysaccharides. To overcome the drawbacks of conventional extraction techniques such as high energy consumption, environmental pollution, and structural degradation, this study adopted alcohol precipitation, a green method offering mild conditions, solvent reusability, and preserved bioactivity. A total polysaccharide yield of 3.75 g/L was obtained from the waste medium. Following purification via ion-exchange chromatography, the polysaccharide fraction PS1 demonstrated significant biological properties. It exhibited antibacterial effects in zebrafish infected with Staphylococcus aureus and Pseudomonas fluorescens, inhibited biofilm formation by 40.86 % and 29.04 % at 1 mg/mL, respectively, and displayed antioxidant capacity. PS1 consisted of mannose, N-acetylglucosamine, glucose confirmed by HPLC and its structure was further characterized by FT-IR, and NMR analysis. As the first report on the extraction and bioactivity assessment of polysaccharides from this waste source, our work offers a sustainable strategy for recycling post-fermentation residues and advancing resource conservation.