Membrane fractionation and characterization of shiitake (Lentinula edodes) polysaccharides with in vitro antifungal activity against phytopathogens.

The shiitake mushroom (Lentinula edodes) is a rich source of bioactive polysaccharides with potential applications in sustainable agriculture, particularly as environmentally friendly alternatives to synthetic fungicides. This study aimed to employ membrane separation technology to streamline the recovery of polysaccharides from shiitake mushrooms and evaluate their antifungal activity against phytopathogens. Crude aqueous extracts and membrane-fractionated polysaccharides were tested in vitro against Colletotrichum gloeosporioides, Fusarium oxysporum, Macrophomina phaseolina, Rhizoctonia solani, and Sclerotinia sclerotiorum. The crude extract exhibited the strongest inhibition, with 13.0 ± 0.07% and 5.87 ± 0.03% growth reduction against R. solani and M. phaseolina, respectively. Membrane ultrafiltration successfully concentrated polysaccharides within a targeted molecular weight range, with glucose, rhamnose, and arabinose confirmed as dominant monosaccharides via HPLC. However, fractionation slightly reduced bioactivity compared to the crude extract. These findings demonstrate that shiitake-derived polysaccharides exhibit measurable in vitro antifungal activity and highlight their potential for further investigation as bioactive natural compounds. Furthermore, the results support the use of membrane separation technology as a sustainable strategy for the recovery and concentration of bioactive mushroom-derived polysaccharides.