title: The use of the tetrazolium salt XTT for the estimation of biological activity of activated sludge cultivated under steady-state and transient regimes.
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.
authors.affiliation: Laboratoire de physiologie et Ecologie Microbienne, Section Interfacultaire d'Agronomie, Université Libre de Bruxelles, C/o Institut Pasteur, Rue Engeland 642, B-1180, Brussels, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Bensaid
authors.forename: J
authors.initials: J
authors.lastname: Thierie
authors.forename: M
authors.initials: M
authors.lastname: Penninckx
mesh_terms: D001419:Bacteria / Q000254:growth & development / Q000378:metabolism*; D018533:Biomass; D002733:Chlorophenols / Q000494:pharmacology; D004579:Electron Transport; D005562:Formazans / Q000378:metabolism; D007202:Indicators and Reagents; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D011190:Potassium Cyanide / Q000494:pharmacology; D012722:Sewage / Q000382:microbiology*; D013778:Tetrazolium Salts / Q000378:metabolism*
chemical_list: D002733:Chlorophenols; D005562:Formazans; D007202:Indicators and Reagents; D012722:Sewage; D013778:Tetrazolium Salts; C059087:2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino)carbonyl)-2H-tetrazolium hydroxide; C116190:3,5-dichlorophenol; D011190:Potassium Cyanide