Two different mechanisms of low-intensity laser photobiological effects on Escherichia coli

Tiina Karu, Olga Tiphlova, Rinat Esenaliev, Vladilen Letokhov

Research output: Contribution to journalArticle

60 Scopus citations


Bacterial suspensions in a phosphate buffer were irradiated at wavelengths λ of 632.8, 1066 and 1286 nm, incubated in Hottinguer broth for 60 min and assayed for viability by the standard surface-plating technique. The difference between the number of viable cells in the irradiated culture and the control was termed growth stimulation. Irradiation of the bacteria with an HeNe laser (632.8 nm) or semiconductor lasers at 1066 and 1286 nm at various intensities and irradiation times produced two maxima in the growth stimulation vs. dose curve. The first maximum, in all cases, occurred near 50 J m-2, and the reciprocity law was obeyed. The second maximum occurred at an irradiation time of 100 s irrespective of the particular radiation intensity, and the reciprocity law was not obeyed. It is assumed that two different mechanisms are responsible for these two maxima in the growth stimulation vs. dose curve.

Original languageEnglish (US)
Pages (from-to)155-161
Number of pages7
JournalJournal of Photochemistry and Photobiology, B: Biology
Issue number3
StatePublished - 1994
Externally publishedYes



  • Escherichia coli WP2
  • HeNe laser
  • Low-poser laser effects
  • Reciprocity law
  • Semiconductor lasers

ASJC Scopus subject areas

  • Plant Science
  • Bioengineering
  • Physical and Theoretical Chemistry

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