Abstract:

【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.

Key words: high hydrostatic pressure (HHP), Escherichia coli, membrane, fluidity