The use of the tetrazolium salt XTT for the estimation of biological activity of activated sludge cultivated under steady-state and transient regimes

J Microbiol Methods. 2000 May;40(3):255-63. doi: 10.1016/s0167-7012(00)00130-5.

Abstract

The tetrazolium salt 3'-¿1-[(phenylamino)-carbonyl]-3, 4-tetrazolium¿-bis (4-methoxy-6-nitro) benzenesulfonic acid hydrate (XTT) was used as a tool for estimating the activity of the electron transport system (ETS) in activated sludge cultivated under steady-state and transient regimes in chemostat culture. Production of formazan by reduction of XTT depended on the initial concentration of the XTT following a saturation law and was proportional to live cell biomass. Addition of cyanide (KCN) to activated sludge gave an initial 1.5-fold increase in XTT reduction, while addition of 3,5-dichlorophenol (3,5-DCP) reduced this value drastically. At steady-state and transient regimes of an activated sludge chemostat, oxygen uptake rate (OUR) and XTT reduction rate were highly correlated and indicated significant variations depending on the growth conditions.

MeSH terms

  • Bacteria / growth & development
  • Bacteria / metabolism*
  • Biomass
  • Chlorophenols / pharmacology
  • Electron Transport
  • Formazans / metabolism
  • Indicators and Reagents
  • Oxidation-Reduction
  • Oxygen Consumption
  • Potassium Cyanide / pharmacology
  • Sewage / microbiology*
  • Tetrazolium Salts / metabolism*

Substances

  • Chlorophenols
  • Formazans
  • Indicators and Reagents
  • Sewage
  • Tetrazolium Salts
  • 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino)carbonyl)-2H-tetrazolium hydroxide
  • 3,5-dichlorophenol
  • Potassium Cyanide