Specific electromagnetic effects of microwave radiation on Escherichia coli

Shamis, Y, Taube, A, Mitik-Dineva, N, Croft, R, Crawford, R and Ivanova, E 2011, 'Specific electromagnetic effects of microwave radiation on Escherichia coli', Applied and Environmental Microbiology, vol. 77, no. 9, pp. 3017-3022.


Document type: Journal Article
Collection: Journal Articles

Title Specific electromagnetic effects of microwave radiation on Escherichia coli
Author(s) Shamis, Y
Taube, A
Mitik-Dineva, N
Croft, R
Crawford, R
Ivanova, E
Year 2011
Journal name Applied and Environmental Microbiology
Volume number 77
Issue number 9
Start page 3017
End page 3022
Total pages 6
Publisher American Society for Microbiology
Abstract The present study investigated the effects of microwave (MW) radiation applied under a sublethal temperature on Escherichia coli. The experiments were conducted at a frequency of 18 GHz and at a temperature below 40°C to avoid the thermal degradation of bacterial cells during exposure. The absorbed power was calculated to be 1,500 kW/m3, and the electric field was determined to be 300 V/m. Both values were theoretically confirmed using CST Microwave Studio 3D Electromagnetic Simulation Software. As a negative control, E. coli cells were also thermally heated to temperatures up to 40°C using Peltier plate heating. Scanning electron microscopy (SEM) analysis performed immediately after MW exposure revealed that the E. coli cells exhibited a cell morphology significantly different from that of the negative controls. This MW effect, however, appeared to be temporary, as following a further 10-min elapsed period, the cell morphology appeared to revert to a state that was identical to that of the untreated controls. Confocal laser scanning microscopy (CLSM) revealed that fluorescein isothiocyanate (FITC)-conjugated dextran (150 kDa) was taken up by the MW-treated cells, suggesting that pores had formed within the cell membrane. Cell viability experiments revealed that the MW treatment was not bactericidal, since 88% of the cells were recovered after radiation. It is proposed that one of the effects of exposing E. coli cells to MW radiation under sublethal temperature conditions is that the cell surface undergoes a modification that is electrokinetic in nature, resulting in a reversible MW-induced poration of the cell membrane.
Subject Physical Chemistry not elsewhere classified
Microbiology not elsewhere classified
Materials Engineering not elsewhere classified
Keyword(s) bacterial-cells
electroporation
permeability
sterilization
permittivity
membranes
DOI - identifier 10.1128/AEM.01899-10
Copyright notice © 2011, American Society for Microbiology. All Rights Reserved.
ISSN 0099-2240
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