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Effect of millimeter waves on survival of UVC‐exposed Escherichia coli
Author(s) -
Rojavin Mikhail A.,
Ziskin Marvin C.
Publication year - 1995
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/bem.2250160307
Subject(s) - escherichia coli , irradiation , microwave , bacteria , specific absorption rate , chemistry , absorption (acoustics) , biophysics , microbiology and biotechnology , optics , biology , physics , biochemistry , genetics , quantum mechanics , nuclear physics , antenna (radio) , gene , telecommunications , computer science
Bacterial cells of the strain Escherichia coli K12 were exposed to millimeter electromagnetic waves (mm waves) with and without additional exposure to ultraviolet light λ = 254 nm (UVC). The mm waves were produced by a medical microwave generator emitting a 4‐GHz‐wide band around a 61 GHz center frequency and delivering an irradiation of 1 mW/cm 2 and a standard absorption rate (SAR) of 84 W/kg to the bacteria. Exposure to the mm waves alone for up to 30 minutes did not change the survival rate of bacteria. Exposure to mm waves followed by UVC irradiation also did not alter the number of surviving E. coli cells in comparison to UVC‐treated controls. When mm waves were applied after the UVC exposure, a dose‐dependent increase of up to 30% in the survival of E. coli was observed compared to UVC + sham‐irradiated bacteria. Because sham controls and experimental samples were maintained under the same thermal conditions, the effect is not likely to be due to heating, although the possibility of nonuniform distribution of microwave heating in different layers of irradiated bacterial suspension cannot be ruled out. The mechanism for this effect appears to involve certain DNA repair systems that act as cellular targets for mm waves. © 1995 Wiley‐Liss, Inc.