Institute of Postharvest and Food Science, Department of Postharvest Science, Volcani Institute, Agricultural Research Organization, Rishon LeZion 7505101, Israel; Institute of Biochemistry, Food Science and Nutrition, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
Institute of Postharvest and Food Science, Department of Postharvest Science, Volcani Institute, Agricultural Research Organization, Rishon LeZion 7505101, Israel.
Int J Biol Macromol. 2022 Jan 1;194:666-675. doi: 10.1016/j.ijbiomac.2021.11.111. Epub 2021 Nov 23.
Chitosan is a nature-sourced polysaccharide widely used in numerous applications. The antibacterial potential of chitosan has attracted researchers to further develop and utilize this polymer for the formation of biocompatible antibacterial agents for both the food and healthcare industries. The tested hypothesis in this study is that modified N-alkylaminated chitosan nanoparticles (CNPs) have selective binding properties to Gram-negative bacteria strains that result in bacterial aggregation. Various bacterial strains were tested of five Gram-negative bacteria including Erwinia carotovora, Escherichia coli, Pseudomonas aeruginosa, Salmonella, and Serratia marcescens, as well as three Gram-positive bacteria strains including Bacillus licheniformis, Bacillus megaterium, and Bacillus subtilis. The fluorescence microscopy characterization showed that the presence of CNPs caused the aggregation of Escherichia coli bacteria cells, where modified CNPs with a shorter chain length of the substituent caused a higher aggregation effect. Moreover, it was found that the CNPs exhibited a selective binding behavior to Gram-negative as compared to Gram-positive bacteria strains, mainly to Escherichia coli and Salmonella. Also, the scanning electron microscopy characterization showed that CNPs exhibited selective binding to Gram-negative bacteria, which was especially understood when both Gram-negative and Gram-positive bacteria strains were within the same sample. In addition, the bacterial viability assay suggests that CNPs with a lower degree of substitution have a higher inhibitory effect on bacterial growth. CNPs with longer side chains had a less inhibitory effect on the bacterial growth of Gram-negative strains, where a concentration-dependent response pattern was only seen for the cases of Gram-negative strains, and not for the case of Gram-positive strain. To conclude, the further understanding of the selective binding of CNPs to Gram-negative bacteria strains may produce new opportunities for the discovery and characterization of effective antibacterial agents.
壳聚糖是一种天然来源的多糖，广泛应用于许多领域。壳聚糖的抗菌潜力吸引了研究人员进一步开发和利用这种聚合物，以形成适用于食品和医疗保健行业的生物相容抗菌剂。本研究的测试假设是，经过修饰的 N-烷基胺化壳聚糖纳米颗粒（CNPs）对革兰氏阴性菌具有选择性结合特性，导致细菌聚集。测试了五种革兰氏阴性菌包括欧文氏菌、大肠杆菌、绿脓杆菌、沙门氏菌和粘质沙雷氏菌的五种不同的细菌菌株，以及三种革兰氏阳性菌包括地衣芽孢杆菌、巨大芽孢杆菌和枯草芽孢杆菌。荧光显微镜特征表明，CNPs 的存在导致大肠杆菌细菌细胞的聚集，其中取代基链长较短的修饰 CNPs 引起更高的聚集效应。此外，研究发现，与革兰氏阳性菌相比，CNPs 对革兰氏阴性菌表现出选择性结合行为，主要是对大肠杆菌和沙门氏菌。此外，扫描电子显微镜特征表明，CNPs 对革兰氏阴性菌表现出选择性结合，当革兰氏阴性和革兰氏阳性菌都在同一个样本中时，这种结合更为明显。此外，细菌活力测定表明，取代度较低的 CNPs 对细菌生长有更高的抑制作用。具有较长侧链的 CNPs 对革兰氏阴性菌的生长抑制作用较小，只有在革兰氏阴性菌的情况下才出现浓度依赖性的反应模式，而在革兰氏阳性菌的情况下则没有。总之，对 CNPs 与革兰氏阴性菌选择性结合的进一步了解可能为发现和表征有效抗菌剂提供新的机会。
