Oligosaccharides are considered to be the key structure of polysaccharides with various biological activity.En-zymatic hydrolysis of polysaccharides to prepare oligosaccharides has attracted extensive attention due to its mild reac-tion conditions and high efficiency.In the present study, mulberry leaf polysaccharides were used as the research subject to prepare functional mulberry leaf oligosacchar-ides through enzymatic degradation.First of all, the effect of enzymes ( cellulase, hemicellulase, xylanase and glu-canase) on the yield of mulberry leaf oligosaccharide was studied by using the yield of oligosaccharides as an indi-cator to determine the optimum enzyme ( hemicellulase ) .On this basis, the single-factor optimization, Plackett-Bur-man ( PB) experiment and response surface optimization were used to determine that in the enzymatic hydrolysis of mulberry leaf polysaccharides for the preparation of oligo-saccharides, the optimal amount of enzyme addition was 60 U/mL, the substrate concentration was 20 mg/mL, the re-action temperature was 55℃, the pH was 4.7, and the time was 8 h.Under this condition, the yield of mulberry leaf oli-gosaccharide was 20.2％, which was close to the model prediction value of 20.7％.Finally, the antibacterial activity of mulberry leaf oligosaccharide was studied.The results showed that compared to polysaccharide, mulberry leaf oligosac-charide could significantly inhibit the growth of Escherichia coli, Salmonella, Shigella dysenteriae and Proteus vulgaris, suggesting that mulberry leaf oligosaccharide was an excellent antibacterial agent.The above results provide theoretical reference for the preparation and application of functional mullberry leaf oligosaccharides.
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