壳聚糖抑菌机制的初步研究

Antibacterial mechanism of chitosan

摘要:

壳聚糖在医学、食品、环保、日化用品等领域有着广泛而重要的应用。近年来, 壳聚糖由于对不同的菌类都具有良好的抑菌效果而被研究者们密切关注。然而, 有关壳聚糖抑菌机制的研究却并不多, 其抑菌机制也没有被完全阐明。在本研究中, 我们发现很多金属离子可以对壳聚糖的抑菌效果产生影响, 高浓度金属离子(0.5%)可以使壳聚糖完全丧失抑菌活性。还发现金黄色葡萄球菌和白色念珠菌在壳聚糖的作用下会发生钾离子和ATP的渗漏, 而且五万分子量的壳聚糖引起钾离子和ATP的渗漏大约比五千分子量壳聚糖多2到4倍。不同分子量的壳聚糖对金黄色葡萄球菌和白色念珠菌都具有较好的抑菌效果, 但是引起钾离子和ATP的渗漏量却存在很大差异, 这说明小分子量壳聚糖很可能存在与大分子量壳聚糖不同的抑菌机制。

关键词:壳聚糖; 金属离子; 抑菌活性; 机制

Abstract:

In this study, we found that many metal ions could affect the antibacterial activity of chitosan, such as K+, Na+, Mg2+ and Ca2+. High concentration (about 0.5%) of metal ions could make chitosan completely lose its antibacterial activity, except for the effect of Na+ on the antibacterial activity against Staphylococcus aureus. We also found that chitosan could weaken the barrier function of the outer membrane of different microorganisms. Large amount of K+ and ATP leakages were observed during exposure of Staphylococcus aureus and Candida albicans to chitosan. Both 50kDa chitosan and 5kDa chitosan had good antibacterial activity against Staphylococcus aureus and Candida albicans, but the 50kDa chitosan could make nearly two to four times amount of K+ and ATP leakages than the 5kDa chitosan. There might have been different antibacterial mechanisms of high-molecular-weight and low-molecular-weight chitosan.

Key words:chitosan; metal ion; antibacterial activity; mechanism