研究壳聚糖和ε-聚赖氨酸对肉食杆菌细胞结构和细胞保护酶的作用,探讨其对肉食杆菌的抑菌作用机制.采用肉汤稀释法测定壳聚糖和ε-聚赖氨酸对肉食杆菌的最小抑菌浓度(minimal inhibitory concentration,MIC),由细菌生长曲线、电导率、胞外核酸、胞外蛋白、碱性磷酸酶(alkaline phosphatase,AKP)活力等指标,并结合扫描电子显微镜(scanning electron microscopy,SEM)观察,综合评价壳聚糖和ε-聚赖氨酸对肉食杆菌的作用机制;通过测定细胞保护酶(超氧化物歧化酶(superoxide dismutase,SOD)和过氧化氢酶(catalase,CAT))的活力变化分析其氧化应激反应参与情况.结果表明:壳聚糖和ε-聚赖氨酸对肉食杆菌的MIC分别为 0.1953和0.1563 mg/mL,经MIC和 2MIC的壳聚糖和ε-聚赖氨酸处理后,菌体细胞内成分(AKP酶、蛋白质、核酸和离子)发生渗漏,CAT和SOD酶活力呈显著下降趋势(P<0.05),且壳聚糖和ε-聚赖氨酸质量浓度与酶活力呈负相关关系.由扫描电镜观察得出,壳聚糖能使菌体变形且内容物渗出,ε-聚赖氨酸则使菌体出现褶皱和扭曲变形,细胞表面生成孔洞.综上所述,壳聚糖和ε-聚赖氨酸均能通过破坏细胞壁、损伤细胞膜、产生氧化应激反应等机制来抑制肉食杆菌的生长.
Abstract
To investigate the effects of chitosan and ε-polylysine on the cell structure and cytoprotective enzymes of Carbibacterium divergens to explore their inhibition mechanism against Carbibacterium divergens,the broth dilution method was used to determine the minimum inhibitory concentrations(MICs)of chitosan and ε-polylysine against Carbibacterium divergens.Their effects on the cellular structure of Carbibacterium divergens were then assessed by several indexes,such as growth curves,electronic conductivity,extracellular nucleic acids,extracellular proteins,and alkaline phosphatase(AKP)activity,and the microstructure of bacteria were also observed by scanning electron microscopy(SEM).In addition,their role in oxidative stress was analyzed by detecting changes in catalase(CAT)activity and superoxide dismutase(SOD)activity.The results showed that the MIC of chitosan and ε-polylysine against Carbibacterium divergens was 0.1953 and 0.1563 mg/mL,respectively.The intracellular components(AKP,proteins,nucleic acids,and ions)leaked after treatment with MIC and 2MIC chitosan and ε-polylysine.The mass concentrations of chitosan and ε-polylysine were negatively correlated with enzyme activity,and the activities CAT and SOD significantly decreased(P<0.05).Scanning electron microscopy showed that chitosan could deform the cell and its contents oozed out,while ε-polylysine caused the cell to fold and distort,forming holes on the cell surface.In summary,both chitosan and ε-polylysine can inhibit the growth of Carbibacterium divergens by destroying cell wall,damaging cell membrane and generating oxidative stress reaction.
维普
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