Relationship between Membrane Damage and Cell Death in Pressure-Treated <i>Escherichia coli</i> Cells: Differences between Exponential- and Stationary-Phase Cells and Variation among Strains

Applied and Environmental Microbiology - Tập 66 Số 7 - Trang 2829-2834 - 2000
Rafael Pagán1, B.M. Mackey1
1Department of Food Science and Technology, University of Reading, Reading RG6 6AP, United Kingdom

Tóm tắt

ABSTRACT The relationship between membrane damage and loss of viability following pressure treatment was examined in Escherichia coli strains C9490, H1071, and NCTC 8003. These strains showed high, medium, and low resistance to pressure, respectively, in stationary phase but similar resistance to pressure in exponential phase. Loss of membrane integrity was measured as loss of osmotic responsiveness or as increased uptake of the fluorescent dye propidium iodide. In exponential-phase cells, loss of viability was correlated with a permanent loss of membrane integrity in all strains, whereas in stationary-phase cells, a more complicated picture emerged in which cell membranes became leaky during pressure treatment but resealed to a greater or lesser extent following decompression. Strain H1071 displayed a very unusual pressure response in stationary phase in which survival decreased to a minimum at 300 MPa but then increased at 400 to 500 MPa before decreasing again. Membranes were unable to reseal after treatment at 300 MPa but could do so after treatment at higher pressures. Membrane damage in this strain was thus typical of exponential-phase cells under low-pressure conditions but of stationary-phase cells under higher-pressure conditions. Heat shock treatment of strain H1071 cells increased pressure resistance under low-pressure conditions and also allowed membrane damage to reseal. Growth in the presence of IPTG (isopropyl-β- d -thiogalactopyranoside) increased resistance under high-pressure conditions. The mechanisms of inactivation may thus differ at high and low pressures. These studies support the view that membrane damage is an important event in the inactivation of bacteria by high pressure, but the nature of membrane damage and its relation to cell death may differ between species and phases of growth.

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Tài liệu tham khảo

Bartlett D. H. (1992) Microbial life at high pressures.Sci. Progr. (Oxford)76:479–496.

10.1128/AEM.65.4.1564-1569.1999

10.1139/m75-253

10.1128/AEM.65.2.409-414.1999

10.1177/108201329500100203

Gould G. W. Sale A. J. H. (1972) Role of pressure in the stabilization and destabilization of bacterial spores.Symp. Soc. Exp. Biol.26:147–157.

10.4315/0362-028X-59.4.350

Hoover D. (1997) Minimally processed fruits and vegetables: reducing microbial load by non-thermal physical treatments.Food Technol.51:66–71.

10.1128/aem.60.11.4174-4177.1994

10.1006/fmic.1997.0155

Knorr D. (1993) Effects of high-hydrostatic-pressure processes on food safety and quality.Food Technol.47:156–161.

10.1128/aem.62.11.3939-3947.1996

10.1007/BF00172194

10.1098/rstb.1984.0008

10.1099/00221287-14-1-69

10.1099/13500872-145-2-419

Patterson M. (1999) High-pressure treatment of foods. in The encyclopedia of food microbiology. eds RobertsonR. K.BattC. A.PatelP. D. (Academic Press London United Kingdom) pp 1059–1065.

10.4315/0362-028X-61.4.432

10.1099/00221287-29-2-233

Ritz M. Pilet M. F. P. Tholozan J. L. Federighi M. (1999) High hydrostatic pressure effects on Salmonella typhimurium . Physiological and morphological damages. in Food microbiology and food safety into the next millennium. Proceedings of the Seventeenth International Conference of the International Committee on Food Microbiology and Hygiene (ICFMH). eds TuijetlaarsA. C. J.SamsonR. A.RomboutsF. M.NotermansS. (TNO Nutrition and Food Research Institute Zeist The Netherlands) pp 295–298.

10.1016/0168-1605(91)90071-V

10.1016/S0924-2244(98)00030-2

10.1080/08957959408201658

10.1038/2031304a0

10.1128/AEM.64.2.509-514.1998

10.1128/AEM.64.9.3220-3224.1998

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Applied and Environmental Microbiology

Tập 66 Số 7

2829-2834

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