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The effects of high-power microwaves on the ultrastructure of Bacillus subtilis

S-Y Kim1, E-K Jo, H-J Kim

  • 1Department of Microbiology and Cancer Research Institute, College of Medicine, Chungnam National University, Daejeon, Korea.

Letters in Applied Microbiology
|June 12, 2008
PubMed
Abstract

Insights

High-power microwave irradiation effectively inactivates Bacillus subtilis by damaging the cell wall and DNA. This method causes distinct ultrastructural changes compared to boiling, highlighting its potent microbicidal mechanisms.

Area of Science:

  • Microbiology
  • Biophysics

Background:

  • Bacillus subtilis is a common bacterium.
  • Understanding microbial inactivation is crucial for sterilization and disinfection.

Purpose of the Study:

  • To investigate the microbicidal mechanisms of high-power microwave (2.0 kW) irradiation on Bacillus subtilis.
  • To determine the effect of microwave irradiation on the ultrastructure of the bacterial cell wall.

Main Methods:

  • Viability testing of Bacillus subtilis.
  • Transmission electron microscopy (TEM) for ultrastructural examination.
  • Measurement of intracellular protein and nucleic acid release.

Main Results:

  • 2.0-kW microwave irradiation showed a higher inactivation rate for Bacillus subtilis compared to 0.5-kW irradiation.
  • Significant leakage of nucleic acids was observed from 2.0-kW microwaved cells.
  • TEM revealed disruption of the cell wall in 2.0-kW microwaved cells, unlike boiled cells.

Conclusions:

  • Microbicidal mechanisms of 2.0-kW microwave irradiation involve cell wall damage, genomic DNA breakage, and cytoplasmic protein coagulation.
  • Ultrastructural changes induced by microwave irradiation differ from those caused by boiling.
  • High-power microwave irradiation offers a distinct method for microbial inactivation.

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