中文摘要：

以大肠杆菌和金黄色葡萄球菌为实验菌，研究壳聚糖的抗菌活性。结果表明：分子量大的壳聚糖对大肠杆菌和金黄色葡萄球菌都有较强的抑菌作用。梯度稀释结果显示，两种壳聚糖的MIC均为：0．05％抑制大肠杆菌，0．025％抑制金黄色葡萄球菌。研究壳聚糖的抑菌机理时发现，当壳聚糖形成纳米粒子时其抑菌能力丧失，推测抑菌作用可能与壳聚糖上氨基的质子化有密切关系。壳聚糖抑菌可能是因为壳聚糖上的氨基（NH^3＋）与细菌细胞壁中带负电荷的磷壁酸或脂多糖结合，并螯合Mg^2＋、Ca^2＋等阳离子，从而改变细胞壁的通透性，起到抑菌作用。

英文摘要：

Antibacterial activity of chitosan was examined against Escherichia coli （E. coli） and Staphylococcus aureus （S. aureus）. Chitosan showed high antibacterial activity against E. coli and S. aureus, with higher molecular weight showed stronger antibacterial activity. The MIC was 0.05% and 0. 025% for E. coli and S. aureus respectively. In addition, this study shows that when chitosan forms nanoparticles it lost antibacterial activity. These resuits indicate that the antibacterial activity of ehitosan had a close relationship with amino protonation of chitosan. Chitosan kills bacteria through cell wall damage. This damage was caused by electrostatic interaction between NH^3＋ groups of chitosan and lipoteichoic acid or lipopolysaccharide of cell wall, and by chelating cations such as Mg^2＋ , Ca^2＋.