Atomic force microscopy study of the antibacterial effects of chitosans on Escherichia coli and Staphylococcus aureus
Atomic force microscopy study of the antibacterial effects of chitosans on Escherichia coli and Staphylococcus aureus
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DOI：
10.1016/j.ultramic.2008.04.015
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发表时间：
2008-09-01
期刊：
影响因子：
2.2
通讯作者：
Malcata, F. Xavier
中科院分区：
文献类型：
--
作者：
Eaton, Peter;Fernandes, Joao C.;Malcata, F. Xavier
壳聚糖被认为是一种无毒、可生物降解的抗菌剂。本工作的目的是阐明壳聚糖的相对分子质量与其对两种模式微生物，一种革兰氏阳性菌(金黄色葡萄球菌)和一种革兰氏阴性菌(大肠杆菌)的抑菌活性之间的关系。利用原子力显微镜(AFM)成像技术获得了壳聚糖对细菌形态影响的高分辨率图像。原子力显微镜测量与活细胞数相关联，这表明这两种物种对高分子壳聚糖和低分子壳聚糖衍生物的反应不同。获得的图像不仅显示了抗菌效果，还显示了细菌使用的反应策略；细胞壁坍塌和形态变化反映了细胞死亡，而细菌聚集似乎与细胞存活有关。此外，原子力显微镜的纳米压痕实验显示，处理后细菌细胞壁发生了机械变化。纳米压痕结果表明，尽管在形态学研究中观察到革兰氏阳性菌几乎没有发生改变，但确实发生了细胞壁破坏，因为壳寡糖处理后细胞壁硬度降低。(C)2008爱思唯尔B.V.保留所有权利。
Chitosan has been reported to be a non-toxic, biodegradable antibacterial agent. The aim of this work was to elucidate the relationship between the molecular weight of chitosan and its antimicrobial activity upon two model microorganisms, one Gram-positive (Staphylococcus aureus) and one Gram-negative (Escherichia coli). Atomic force microscopy (AFM) imaging was used to obtain high-resolution images of the effect of chitosans on the bacterial morphology. The AFM measurements were correlated with viable cell numbers, which show that the two species reacted differently to the high- and low-molecular-weight chitosan derivatives. The images obtained revealed not only the antibacterial effects, but also the response strategies used by the bacteria; cell wall collapse and morphological change, reflected cell death, whereas clustering of bacteria appeared to be associated with cell survival. m addition, nanoindentation experiments with the AFM revealed mechanical changes in the bacterial cell wall induced by the treatment. The nanoindentation results suggested that despite little modification observed in the Gram-positive bacteria in morphological studies, cell wall damage had indeed Occurred, since cell wall stiffness was reduced after chitooligosaccharide treatment. (C) 2008 Elsevier B.V. All rights reserved.