壳聚糖抑菌作用位点的研究

摘要

Chitosans with different molecular weights （3, 300 -- 400 kD and 700 kD） were labeled with fluorescein isothiocyanate （FITC-CT） and tested for their antibacterial activity in vitro. Besides, confocal laser scanning microscope was used to study the antibacterial action sites of fluorescently labeled chitosans in E.coli. The results indicated that all 3, 300 -- 400 kD and 700 kD fluorescently labeled chitosans had antibacterial activity, although their inhibitory rates were decreased by 4.22%, 19.56% and 14.54%, respectively compared to their corresponding non-labeled counterparts. The antibacterial action site of 3 kD chitosan, which could enter bacterial cells, may be a given substance in bacterial cells, while 300--400 kD and 700 kD chitosans could not enter bacterial cells so that their antibacterial action site was presumably the surface of bacterial cell membrane.%采用异硫氰酸荧光素标记3种分子质量（3kD、300-400kD与700kD）壳聚糖，体外检测荧光标记壳聚糖的抑菌活性，并运用激光共聚焦显微镜研究荧光标记壳聚糖对大肠杆菌的抑菌作用位点。结果表明：荧光标记壳聚糖依然具有抑菌活性，但相对未标记壳聚糖而言，3种壳聚糖的抑菌活性分别减小了4．22％、19．56％和14．54％。小分子质量（3kD）壳聚糖能进入细菌内部，其抑菌位点可能为细菌细胞内某物质，大分子质量（300～400kD和700kD）壳聚糖则不能进入细菌内部，其抑菌位点可能为细菌细胞膜。