Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/190976

Title

Specific electromagnetic effects of microwave radiation on Escherichia coli

Author(s)

Shamis, Yury;  Taube, Alex;  Mitik-Dineva, Natasa;  Croft, Rodney;  Crawford, Russell J.;  Ivanova, Elena P.

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 degrees C to avoid the thermal degradation of bacterial cells during exposure. The absorbed power was calculated to be 1,500 kW/m(3), 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 degrees 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.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Life and Social Sciences

Source

Applied and Environmental Microbiology, Vol. 77, no. 9 (May 2011), pp. 3017-3022

Publication year

2011

FOR Code(s)

06 Biological Sciences;  07 Agricultural and Veterinary Sciences;  10 Technology

Keyword(s)

Bacterial cells;  E. coli bacteria;  Electromagnetic effects;  Electroporation;  Escherichia coli;  Membranes;  Microwave radiation;  Permeability;  Permittivity;  Sterilization

Publisher

American Society for Microbiology

ISSN

0099-2240

Publisher URL

http://dx.doi.org/10.1128/aem.01899-10

Copyright

Copyright © 2011, American Society for Microbiology. All Rights Reserved.

Peer reviewed