不同分子量壳聚糖抑菌作用的研究

随着壳聚糖研究的不断深入，其不同寻常的抑菌活性引起了学者们的广泛关注。为了获得壳聚糖对桉树青枯病病原菌极其拮抗菌的抑制活性，在研究中考察了不同分子量的壳聚糖对桉树青枯病的生防菌302-多粘类芽孢杆菌、199-蜡状芽孢杆菌及桉树白枯病的病原菌76-茄青枯拉尔氏菌、RS-桉树青枯病原菌的抑制效果。采用琼脂扩散纸片法研究了不同浓度和分子量的壳聚糖对上述4种菌的抑制效果，利用了系列稀释法研究了不同分子量的壳聚糖的最小抑菌浓度。同时研究了分子量为2200的壳聚糖在不同pH条件下的抑菌效果。结果表明，5种不同分子量的壳聚糖对76-茄青枯拉尔氏菌和RS-桉树青枯病病原菌有明显的抑制作用，其中分子量为2200和5万的壳聚糖对青枯病原菌的抑菌效果最好，且随壳聚糖浓度的增大，壳聚糖的抑菌作用逐渐增强，最小抑菌浓度在0.05%以上。而这2种分子量的壳聚糖对302-多粘类芽孢杆菌和199-蜡状芽孢杆菌的抑菌效果较上述2种病原菌要明显弱很多，最小抑菌浓度在0.1%以上。在上述试验的基础上，本试验进一步探讨了分子量为2200的壳聚糖在不同pH条件下对4种受试菌的抑制效果。结果表明，当pH在5.5~6.5时，对受试菌具有最佳的抑制效果。壳聚糖对上述4种菌的作用效果尚未见文献报道。

The Antibacterial Effect of Different Molecular Weight of Chitosan on Four Bacterial

In recent years, with the development of research on chitosan, its unusual antibacterial activity attracted wide attention of scholars. In this study, in order to obtain the antibacterial effect of chitosan on eucalyptus Ralstonia bacteria and its antagonistic bacteria, the inhibition effect of different molecular weight of chitosan on 302- Paenibacillus polymyxa, 199- Bacillus cereus, 76- eggplant Ralstonia Lal coli and RSeucalyptus Ralstonia bacteria were researched. The method of disc agar diffusion was used to study antibacterial activity of different molecular weight of chitosan. The method of serial dilution was used to determine the minimal inhibitory concentration (MIC) of different molecular weight of chitosan. At the same time, the antibacterial effect of the molecular weight of 2200 chitosan under different pH value was also explored. The results showed that the inhibition effect of different molecular weights of chitosan on 76-eggplant Ralstonia Lal and RS-coli bacterial wilt pathogen was significant; especially the molecular weight of 2200 and 50000 chitosan has the best inhibition effect. With the increasing of chitosan concentration, the inhibition effect on the two bacteria above gradually increased, the Mic (minimum inhibitory concentration) was above 0.05%. The inhibition effect of different molecular weight chitosan on 302-Paenibacillus polymyxa and 199-Bacillus cereus was weaker comparing to 76-eggplant Ralstonia Lal and RS-coli bacterial wilt pathogen, the Mic was 0.1%. The best antibacterial effect was obtained on pH 5.5-6.5. So far, the antibacterial effect of different molecular weight of chitosan on the bacterial strain above had not been reported.