超高压对大肠杆菌细胞膜流动性的影响

Effects of High Hydrostatic Pressure on Membrane Fluidity of Escherichia coli

【目的】对超高压作用后大肠杆菌细胞膜的荧光偏振度和微黏度的影响进行研究,探讨超高压对大肠杆菌细胞膜流动性的影响。【方法】以1,6-二苯基-1,3,5,-己三烯(DPH)为荧光探针标记大肠杆菌细胞膜,用荧光偏技术测定大肠杆菌细胞膜经超高压作用后荧光偏振度和微黏度的变化。【结果】建立了用DPH标记和荧光偏振法测定大肠杆菌细胞膜流动性条件;不同的处理压力和时间对大肠杆菌细胞膜的荧光偏振度和微黏度的影响不同,350～400MPa作用15～40min,细胞膜荧光偏振度及微黏度达到稳定水平,350MPa作用15min已经使细胞膜流动性显著降低(P<0.05)。【结论】随着压力的增大和保压时间的延长,大肠杆菌细胞膜荧光偏振度及微黏度增大,流动性降低,大肠杆菌死亡数增加。当压力和保压时间增加到一定程度(350MPa,15min),荧光偏振度及微黏度达到相对稳定状态,大肠杆菌几乎全部死亡,说明在超高压的作用下大肠杆菌细胞膜荧光偏振度和微黏度的变化与死亡相关性好(P<0.05),这为超高压灭活大肠杆菌提供了理论证据。

【Objective】 Effects of high hydrostatic pressure （HHP） on the fluorescence polarization and microviscidity of Escherichia coli membrane were investigated, and the effect of HHP on the fluidity of E. coli membrane was explored. 【Method】In the present study, 1,6-diphenyl-1,3,5-hexatriene （DPH） was used as fluorescence probe to label the membrane of E. coli, and to determine the changes of fluorescence polarization and microviscidity of E. coli membrane by fluorescence polarization technique after HHP treatments. 【Result】 The conditions were established to measure the membrane fluidity of E. coli membrane by labeling with DPH and the method of fluorescence polarization. The experimental results also indicated that the effects of HHP on fluorescence polarization and microviscidity of E. coli membrane were different under different HHP treatment conditions. The fluorescence polarization and microviscidity of E. coli membrane kept stable levels at pressures of 350-400 MPa for 15 to 40 min, however, the membrane fluidity was decreased significantly at 350 MPa for 15 min （P〈0.05）. 【Conclusion】 The fluorescence polarization and microviscidity of E. coli membrane, and the reductions of E. coli increased with increasing pressure and pressure holding time. The membrane fluidity decreased with increase of pressure and pressure holding time. When pressure and pressure holding time reached a certain degree （350 MPa, 15 min）, the fluorescence polarization and microviscidity of E. coli membrane kept stable levels, and the initial amount of E. coli was nearly inactivated by HHP. In summary, it can be concluded that the changes of fluorescence polarization and microviscidity of E. coli membrane are much more related to cell reduction subjected to HHP, which provide some theoretical evidences for mechanisms of HHP sterilization.