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[Alterations of membrane permeability in Escherichia coli and Staphylococcus aureus under microwave]

Wei Chen1, Feng Hang, Jian-xin Zhao

  • 1School of Food Science & Technology, Southern Yangtze University, Wuxi 214122, China. weichen@sytu.edu.cn

Wei Sheng Wu Xue Bao = Acta Microbiologica Sinica
|October 20, 2007
PubMed

Insights

Microwave treatment increases cell membrane permeability in E. coli and S. aureus, correlating with microbial death. This suggests membrane damage is a key factor in microwave-induced cell death.

Area of Science:

  • Microbiology
  • Biophysics
  • Biochemistry

Background:

  • Cell membrane permeability is a critical factor in microbial survival.
  • Microwave irradiation is known to affect microorganisms, but the exact mechanisms are debated.
  • Previous methods for assessing membrane permeability lack accuracy and sensitivity.

Purpose of the Study:

  • To investigate the effect of microwave treatment on the cell membrane permeability of E. coli and S. aureus.
  • To correlate changes in membrane permeability with microbial inactivation rates.
  • To explore the role of calcium influx in microwave-induced cell damage.

Main Methods:

  • Utilized fluorescein diacetate (FDA) and fluo-3/AM fluorescent probes to quantify membrane permeability.
  • Exposed E. coli and S. aureus to varying microwave temperatures (50-65°C).
  • Measured intracellular calcium levels and fluorescence intensity as indicators of permeability.

Main Results:

  • Microwave treatment significantly increased cell membrane permeability in E. coli (20.7%–89.8%) and S. aureus (4.1%–21.9%) in a temperature-dependent manner.
  • Increased membrane permeability correlated directly with higher microbial fatality rates.
  • Observed influx of extracellular calcium (Ca2+) into cells, indicating compromised membrane integrity.

Conclusions:

  • Alteration of cell membrane permeability is a significant mechanism contributing to microwave-induced microbial cell death.
  • The use of fluorescent probes provides a sensitive and accurate method for assessing membrane permeability changes.
  • Microwave treatment can lead to non-thermal effects on cell membranes, impacting microbial viability.

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