Antibacterial Activity of Chitosan Composite Preservative against Pseudomonas fluorescens
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Abstract:
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.
