壳聚糖对液化沙雷氏菌的抑菌效果及机制

Antibacterial Effect and Mechanism of Chitosan Against Serratia liquefaciens

该文对壳聚糖对液化沙雷氏菌的抑菌效果及机制进行研究。测定壳聚糖对液化沙雷氏菌的最小抑菌浓度(minimalinhibitoryconcentration,MIC),测定壳聚糖作用前后的细菌生长曲线、细胞壁及细胞膜完整性(电导率、胞外核酸含量、胞外蛋白含量、碱性磷酸酶活性)、细胞酶(过氧化氢酶、超氧化物歧化酶)活性及观察扫描电子显微镜下液化沙雷氏菌的细胞形态变化,综合分析壳聚糖对液化沙雷氏菌的抑菌效果及机制。结果表明,壳聚糖对液化沙雷氏菌的MIC为6 mg/mL。经其处理后,液化沙雷氏菌生长被抑制,电导率、胞外核酸含量、胞外蛋白含量、碱性磷酸酶活性等趋势增加,细胞壁及细胞膜完整性被破坏。过氧化氢酶活性、超氧化物歧化酶活性降低,细胞正常代谢被破坏,细胞发生损伤。扫描电子显微镜观察到菌体形态异常,细胞膜表面变得粗糙,细胞皱缩。壳聚糖能够改变液化沙雷氏菌的细胞壁及细胞膜完整性,影响其正常代谢,细胞形态变扭曲,有效控制其生长。

Chitosan’s antibacterial effect and mechanism against Serratia liquefaciens were studied.The mini-mal inhibitory concentration(MIC)of chitosan on S.liquefaciens was determined.To comprehensively analyze chitosan’s effect on S.liquefaciens,bacterial growth curve,cell wall and cell membrane integrity(conductiv-ity,extracellular nucleic acid content,extracellular protein content,alkaline phosphatase activity),and cell enzyme activity(catalase,superoxide dismutase)before and after chitosan treatment were measured while the changes in cell morphology of S.liquefaciens were observed with the electron microscope.The results showed that the MIC of chitosan against S.liquefaciens was 6 mg/mL.After chitosan treatment,the growth of S.liquefa-ciens was inhibited,and conductivity,as well as the content of extracellular nucleic acid,extracellular pro-tein,and alkaline phosphatase increased.Cell wall and cell membrane integrity were destroyed.Catalase and superoxide dismutase activity was reduced,normal cell metabolism was disrupted and the cells were injured.According to scanning electron microscopy observation,the morphology of the bacteria was abnormal with rough cell membrane surface and crumpled cells.In conclusion,chitosan was able to change S.liquefaciens’cell wall and cell membrane integrity,disrupting its normal metabolism and distorting the cell morphology,thus effectively controlling its growth.