Modulation of fluorescence in Heliobacterium modesticaldum cells

Aaron M. Collins, Kevin Redding, Robert E. Blankenship

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


In what appears to be a common theme for all phototrophs, heliobacteria exhibit complex modulations of fluorescence yield when illuminated with actinic light and probed on a time scale of μs to minutes. The fluorescence yield from cells of Heliobacterium modesticaldum remained nearly constant for the first 10-100 ms of illumination and then rose to a maximum level with one or two inflections over the course of many seconds. Fluorescence then declined to a steady-state value within about one minute. In this analysis, the origins of the fluorescence induction in whole cells of heliobacteria are investigated by treating cells with a combination of electron accepters, donors, and inhibitors of the photosynthetic electron transport, as well as varying the temperature. We conclude that fluorescence modulation in H. modesticaldum results from acceptor-side limitation in the reaction center (RC), possibly due to charge recombination between P800+ and A0-.

Original languageEnglish (US)
Pages (from-to)283-292
Number of pages10
JournalPhotosynthesis research
Issue number2
StatePublished - Jun 2010


  • Fluorescence induction
  • Fluorescence modulation
  • Heliobacterium modesticaldum

ASJC Scopus subject areas

  • Biochemistry
  • Plant Science
  • Cell Biology


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