Different effects of microwaves and conventional heating on bacteriophage λ proliferation in E. coli

Abstract

The proliferation of bacteriophage ? in E. coli was used as a model to compare the effects of microwaves and conventional heating on cell metabolism. Irradiation was carried out in a single-mode focused reactor at 2.45 GHz, under an absorption rate of 0.8?0.1 W/g and at constant temperature (33?C or 37?C). The kinetic curve of phage release from cells irradiated at 37?C was decreased as compared to the control, but significantly increased at 33?C. This was attributed to local overheating of cells by microwaves. Based on the conventional heating experiments, performed at 33?C, 37?C, 41?C and 45?C, we estimated that microwave-induced overheating inside cells was between 4?C and 8?C. However, this should have a limited effect on virus proliferation at 33?C, contrary to the obtained results. The increased expression of heat shock proteins (HSP) was proposed to be responsible for the observed effect of microwaves on virus proliferation.