On the use of tetrazolium salts for the measurement of microbial activity in sediments

Aharon Oren*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


In an attempt to understand the significance of microbiol activity measurements in anaerobic sediments by the tetrazolium reduction assay I examined the effect of addition of tetrazolium salts on a variety of anaerobic bacteria of different metabolic types. Triphenyletrazolium chloride was found to be reduced by a variety of obligately anaerobic bacteria that lack cytochromes, and evolve hydrogen during fermentation; thus the assay not only measures respiratory electron transport as was often assumed. Hydrogen evolution is inhibited in hydrogen-producing fermentative bacteria upon addition of tetrazolium salts, thereby depriving, e.g., the surfate-reducing bacteria of an important electron donor. Moreover, a dissimilatory sulfate-reducing bacterium tested did not reduce tetrazolium salts at significant rates. It is thus suggested that the tetrazolium reduction assay applied to anaerobic ecosystems gives a measure for activity of hydrogen-evolving fermentative bacteria, rather than for overall bacterial metabolism or of anaerobic respiration.

Original languageAmerican English
Pages (from-to)127-133
Number of pages7
JournalFEMS Microbiology Letters
Issue number3
StatePublished - Jun 1987


  • Anaerobic settlement
  • Hydrogen evolution
  • Microbial activity
  • Tetrazolium salt


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