几种壳聚糖的抑菌性能

通过壳聚糖的抑菌实验和几种壳聚糖的最低抑菌浓度的测定 ,比较了相同脱乙酰度不同分子量 ,以及分子量相近脱乙酰度不同的壳聚糖对金黄色葡萄球菌、枯草杆菌、大肠杆菌和假单胞菌的抑菌作用。结果表明 ,实验中用到的壳聚糖都对金黄色葡萄球菌有很强的抑菌作用 (抑菌率接近 10 0 % ,最低抑菌浓度为 0 0 3% ) ;对于其他 3种细菌 ,脱乙酰度相同 (为 75 3%或 93 7% ) ,粘均分子量不同 (在 4 0～ 80万之间 )的壳聚糖 ,抑菌作用随分子量的升高而增强 ;而分子量相近脱乙酰度不同的壳聚糖对上述 4种细菌的抑菌作用差别不大 ;在 pH 5 5左右至 pH 6 0左右壳聚糖能够发挥最强的抑菌作用 ;总体看来 ,壳聚糖对金黄色葡萄球菌的抑菌作用最强 ,其次是对假单胞菌和枯草杆菌 ,壳聚糖对大肠杆菌的抑菌作用相对弱一些 ;实验条件下的壳聚糖对上述 4种细菌的抑菌作用普遍比苯甲酸钠强。

A Study on the Antibacterial Activities of Chitosans

Chitosans with different degree of deacetylation(DD) were prepared from crab chitin by alkali method. Chitosans with same DD but different viscosity average molecular weight(MW) were achieved through ultrasonic degradation from chitosan CS0811(DD=75.3%) and chitosan CS0903(DD=93.7%). Antibacterial activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas fluorescens of the above chitoans were investigated in the study. The effect of pH to the antibacterial activity of chitosan(CS0811-30) was investigated and the minimal inhibitory concentration (MIC) of chitosans against the described bacteria were obtained.Our results showed that all chitosans used in the experiment have strong antibacterial activity against S. aureus. As for the other bacteria used in the experiment, the antibacterial activity of chitosans with same DD with then increase with chitosan MW, while the antibacterial activities of chitosans having different DD but same MW of the three bacteria were also some.Chitosan had the highest antibacterial activity at pH5.5 to pH6.0. It was seen that the growth of S. aureus the be easily inhibited by chitosans, followed by B. subtilis and P. aeruginosa and E.coli was the most difficult bacterium to be inhibited in the present experiment. In general, all chitosans in the study had high antibacterial activity against the described four bacterial and and their activityies were higher than sodium benzoate(C_7H_5O_2Na).