Inhibition of Escherichia coli respiratory enzymes by short visible femtosecond laser irradiation

Chieh Han Lu*, Kung Hsuan Lin, Yung Yuan Hsu, Kong Thon Tsen, Yung Shu Kuan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


A visible femtosecond laser is shown to be capable of selectively inactivating a wide spectrum of microorganisms in a wavelength and pulse width dependent manner. However, the mechanism of how a visible femtosecond laser affects the viability of different microorganisms is still elusive. In this paper, the cellular surface properties, membrane integrity and metabolic rate of Escherichia coli (E. coli) irradiated by a visible femtosecond laser (λ=415nm, pulse width=100fs) with different exposure times were investigated. Our results showed that femtosecond laser treatment for 60min led to cytoplasmic leakage, protein aggregation and alternation of the physical properties of the E. coli cell membrane. In comparison, a 10min exposure of bacteria to femtosecond laser irradiation induced an immediate reduction of 75% in the glucose-dependent respiratory rate, while the cytoplasmic leakage was not detected. Results from enzymatic assays showed that oxidases and dehydrogenases involved in the E. coli respiratory chain exhibited divergent susceptibility after laser irradiation. This early commencement of respiratory inhibition after a short irradiation is presumed to have a dominant effect on the early stage of bacteria inactivation.

Original languageEnglish
Article number315402
JournalJournal of Physics D: Applied Physics
Issue number31
Publication statusPublished - 2014 Aug 6


  • bacteria inactivation
  • femtosecond lasers
  • respiratory inhibition

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films


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