ABSTRACT
Antibacterial effects of the electromagnetic irradiation (EMI) of 51.8 and 53 GHz frequencies with low intensity (the flux capacity of 0.06 mW/cm(2)) and non-thermal action were investigated upon direct irradiation of E. coli K12. Significant decrease in bacterial growth rate and in the number of viable cells, marked change in H(+) and K(+) transport across membrane were shown. Subsequent addition of kanamycin or ceftriaxone (15 or 0.4 µM, respectively) enhanced the effects of irradiation. This was maximally achieved at the frequency of 53 GHz. These all might reveal membrane as probable target for antibacterial effects. Apparently, the action of EMI on bacteria might lead to changed membrane properties and to antibiotic resistance. The results should improve using extremely high frequency EMI in combination with antibiotics in biotechnology, therapeutic practice, and food industry.
Subject(s)
Anti-Bacterial Agents/pharmacology , Escherichia coli K12/drug effects , Escherichia coli K12/radiation effects , Microbial Viability/drug effects , Microbial Viability/radiation effects , Radiation , Biological Transport , Cell Membrane/metabolism , Colony Count, Microbial , Hydrogen/metabolism , Potassium/metabolismABSTRACT
The coherent electromagnetic radiation (EMR) of the frequency of 51.8 and 53 GHz with low intensity (the power flux density of 0.06 mW/cm(2)) affected the growth of Escherichia coli K12(lambda) under fermentation conditions: the lowering of the growth specific rate was considerably (approximately 2-fold) increased with exposure duration of 30-60 min; a significant decrease in the number of viable cells was also shown. Moreover, the enforced effects of the N,N'-dicyclohexylcarbodiimide (DCCD), inhibitor of H(+)-transporting F(0)F(1)-ATPase, on energy-dependent H(+) efflux by whole cells and of antibiotics like tetracycline and chloramphenicol on the following bacterial growth and survival were also determined after radiation. In addition, the lowering in DCCD-inhibited ATPase activity of membrane vesicles from exposed cells was defined. The results confirmed the input of membranous changes in bacterial action of low intensity extremely high frequency EMR, when the F(0)F(1)-ATPase is probably playing a key role. The radiation of bacteria might lead to changed metabolic pathways and to antibiotic resistance. It may also give bacteria with a specific role in biosphere.
