该实验以质量分数1.5%壳聚糖、0.14% ε-聚赖氨酸、0.15% D-异抗坏血酸钠组成复合保鲜剂，以荧光假单胞菌为实验菌株，探究壳聚糖复合保鲜剂对水产品中的优势菌的抑菌性能和机理。实验方法：通过测定最小抑菌浓度（MIC）、抑菌圈、细菌生长曲线考察保鲜剂对荧光假单胞菌的抑菌活性，测定OD260值、ATP酶和AKP酶活性的变化，细胞超微结构（SEM）和SDS凝胶电泳法研究保鲜剂的抑菌机制。结果表明：壳聚糖复合保鲜剂对荧光假单胞菌的最低抑菌浓度（MIC）为2.24 mg/mL。壳聚糖复合保鲜剂有着显著的抑菌活性，壳聚糖复合保鲜剂导致菌体的细胞壁膜通透性增大、完整性被破坏，菌体内ATP和AKP酶活性被抑制，显著低于（P<0.05）对照组；SDS凝胶电泳表明壳聚糖复合保鲜剂使菌蛋白条带颜色变浅且造成部分蛋白条带消失；细菌超微结构（SEM）显示壳聚糖复合保鲜剂使菌体发生变形破裂，内容物大量流出，导致菌体死亡。结论：该研究证明了壳聚糖复合保鲜剂良好的抑菌性能，研究了保鲜剂对荧光假单胞菌的抑菌机理，为水产品可食性涂膜保鲜的研发提供理论支持。

In this experiment, 1.5% chitosan, 0.14% ε-polylysine and 0.15% D-sodium isoascorbate were used to form a composite preservative, and Pseudomonas fluorescens was used as the experimental strain for investigating the inhibitory property and inhibition mechanism of the chitosan composite preservative against the dominant bacteria in aquatic products. Experimental methods: The inhibitory activity of the preservative against Pseudomonas fluorescens was investigated by measuring the minimum inhibitory concentration (MIC), inhibition zone and bacterial growth curve. The changes in OD260 value, ATPase and AKP enzymatic activities were determined, and SEM (for examining cellular ultrastructure) and SDS gel electrophoresis were used to study the antibacterial mechanism of the preservative. The results showed that the MIC of the chitosan composite preservative against Pseudomonas fluorescens was 2.24 mg/mL. The chitosan composite preservative exhibited significant antibacterial activity, and increased the permeability of cell wall membranes, destroyed the integrity of cell wall membranes, and inhibited the activities of ATP and AKP enzymesin the bacteria, compared with the control group (P<0.05). SDS gel electrophoresis showed that the chitosan composite preservative made the color of bacterial protein bands lighter and caused some protein bands to disappear; Bacterial ultrastructure analysis (by SEM) revealed that the chitosan composite preservative made the bacterial body deformed and ruptured, caused the contents to flow outin large quantities, resulting in the death of the bacteria strain. Conclusion: This study proved that the chitosan composite preservative has good antibacterial properties, and examined its antibacterial mechanism against Pseudomonas fluorescens, which provides theoretical support for the research and development of edible coatings for preservation of aquatic products.

辽宁省教育厅基本科研项目（重点项目）（LJKZ0802）；锦州医科大学横向课题（2021年031号）