Publication Details (including relevant citation information):
Oral and Poster presentations, FEMS 2015: 6th Congress of European Microbiologists, Maastricht, Netherlands (2015)
Background: Biological systems are frequently exposed to microwave radiation. Many studies have investigated the influence of microwaves on biological systems, but controversy over methods to distinguish between thermal and non-thermal microwave effects remains.
Objectives: To differentiate between thermal and non-thermal microwave effects on a physiology of a microorganism, a thermophilic bacterium was grown in a constant-temperature microwave and was compared to convection heating under identical conditions. Comparing the growth properties of a thermophile will reveal non-thermal microwave effects on cell growth and physiology. Biophysical and biochemical analysis will demonstrate changes in morphology and chemical composition arising from microwave exposure.
Methods: Cell growth was analyzed by optical density (OD) measurements (supported by independent quantitative DNA analysis), and cell morphologies were characterized using electron microscopy imaging (SEM, TEM), dynamic light scattering (DLS), and atomic force microscopy (AFM). AFM was also used to probe the biophysical characteristics of the cells, in conjunction with nano-infrared spectroscopy (Nano-IR). Attenuated total reflectance infrared spectroscopy (ATR-IR) and fatty acid methyl ester (FAMEs) analysis were used to determine biochemical differences between cells grown in microwave and oven conditions.
Conclusions: Thermophilic bacteria were grown in a synthetic microwave such that thermal effects and microwave effects were distinguishable. These data demonstrate that there are physiological differences between cells cultured in a dielectric field and a convection oven, and that microwaves induce non-thermal changes to the structure, physiology, and chemical composition of the organism.
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