Abstract In this paper, the antimicrobial activity and mechanism of a laccase-catalyzed chitosan–gallic acid derivative were evaluated. The results showed that compared to the parent chitosan, the derivative could significantly inhibit the growth of Escherichia coli and Staphylococcus aureus, wherein the latter was more sensitive to the derivative than the former. The chitosan–gallic acid derivative could disrupt the cell membrane of E. coli and S. aureus, resulting in leakage of cytoplasm and an increase in relative conductivity. The morphological changes were manifested by the aggregation of bacterial cells and formation of an irregular shape. Agarose gel electrophoresis showed that chitosan derivatives could enter bacterial cells through damaged cell membranes and inhibit DNA synthesis in the nucleus. In addition, the cytotoxicity was significantly reduced by proper modification of chitosan with gallic acid. The above results indicated that there was a great potential for laccase-catalyzed chitosan–gallic acid derivative for use as a food preservative.

中文翻译：

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漆酶催化的壳聚糖-没食子酸衍生物对大肠杆菌和金黄色葡萄球菌的抗菌活性和机制

摘要 在本文中，评价了漆酶催化的壳聚糖-没食子酸衍生物的抗菌活性和机理。结果表明，与母体壳聚糖相比，该衍生物能显着抑制大肠杆菌和金黄色葡萄球菌的生长，其中后者对衍生物的敏感性高于前者。壳聚糖-没食子酸衍生物可以破坏大肠杆菌和金黄色葡萄球菌的细胞膜，导致细胞质泄漏和相对电导率增加。形态变化表现为细菌细胞的聚集和不规则形状的形成。琼脂糖凝胶电泳显示壳聚糖衍生物可以通过受损的细胞膜进入细菌细胞，抑制细胞核内的DNA合成。此外，用没食子酸对壳聚糖进行适当的修饰可以显着降低细胞毒性。上述结果表明，漆酶催化的壳聚糖-没食子酸衍生物作为食品防腐剂具有很大的潜力。