> From: Email at dl.ac.uk (YourName)
> I use tetrazolium red to indicate metabolic activity of micro-
> organisms (Pseudomonads) on certain carbon sources. Some references
> point to the usefulness of this method, e.g. J.Lederberg showed
> that:
> - bacteria grown on non-acidifying carbon sources in the agar plate
> turn tetrazolium red to a red color;
> - bacteria grown on acidifying carbon sources (fermentation:
> glucose, lactose) do not convert terazolium
> My problem is, that I seem unable to find out, or at least get some
> literature, on the bacterial enzymes and reactions that convert
> tetrazolium. Lederberg wrote about a "dehydrogenase".
> Can anyone give some hints where to look in literature ??
> Just wondering what I'm looking at...... thanks in advance,
> Marco Simons
> Institute for molecular plant sciences, Clusius laboratory,
> Leiden University, Wassenaarseweg 64, Leiden, the Netherlands
>SBY3MS at RULSFB.LEIDENUNIV.NL
> From: benedik at uh.edu (benedik at uh.edu)
> Tetrazolium is acting as a pH indicator.
> Michael Benedik benedik at uh.edu> Biochemical Sciences, University of Houston, Houston, TX 77204-5934
The correct answer is: tetrazolium salts work as REDOX DYER. Converta-
tion/non-convertation of tetrazolium is connected with type of reacti-
on: metabolism respiratory or fermentative. Examples of publications
are:
1. A.S. Kaprelyants, D.B. Kell // The Use of 5-Cyano-2,3-Ditolyl
Tetrazolium Chloride and Flow Cytometry for the Visualisation of
RESPIRATORY ACTIVITY in Individual Cells of Micrococcus-Luteus.
Journal of Microbiological Methods 17: 2 (MAR 1993): 115-122.
(5-cyano-2,3-ditolyl tetrazolium chloride is a REDOX DYE which may
be reduced to a fluorescent formazan derivative.)
2. S.M. Thom, R.W. Horobin, E. Seidler, M.R. Barer // Factors
Affecting the Selection and Use of Tetrazolium Salts as Cytochemical
Indicators of Microbial Viability and Activity. Journal of Applied
Bacteriology 74: 4 (APR 1993): 433-443.
(The reduction of four tetrazolium cations (TCs), nitroblue tetra-
zolium (NBT), neotetrazolium (NT), methylthiazolyldiphenyltetra-
zolium (MTT) and iodonitrophenyltetrazolium (INT), by viable micro-
organisms was examined. In general, formazan deposition could be
accelerated by the addition of glucose and an intermediate electron
carrier (IEC) to the reaction mixture, although INHIBITORY EFFECTS
OF IECs WERE DETECTED.)
3. P. Roslev, G.M. King // Application of a Tetrazolium Salt with a
WaterSoluble Formazan as an Indicator of Viability in RESRIRING
Bacteria. Applied and Environmental Microbiology 59: 9 (SEP 1993):
2891-2896.
(The tetrazolium salt sodium 3'-{1-[(phenylamino)-carbonyl]-3,4-
tetrazolium}-bis (4-methoxy-6- nitro)benzenesulfonic acid hydrate
(XTT) was examined for RESPIRING bacteria. XTT was reduced to an
orange, water-soluble formazan product by Methylosinus trichosporium
OB3b, Pseudomonas putida, Escherichia coli, and Bacillus subtilis.
Formazan production was proportional to live cell biomass, and XTT
was reduced by all cultures IN THE ABSCENCE OF ADDED ELECTRON-
COUPLING AGENTS.)
4. G. Schaule, H.C. Flemming, H.F. Ridgway // Use of 5-Cyano-2,3-Dito-
lyl Tetrazolium Chloride for Quantifying Planktonic and Sessile RESPI-
RING Bacteria in Drinking Water. Applied and Environmental
Microbiolo- gy 59: 11 (NOV 1993): 3850-3857.
(Samples were incubated with the vital redox dye 5-cyano-2,3-ditolyl
tetrazolium chloride (CTC) and R2A medium. One hour of incubation
with 0.5 mM CTC was sufficient to obtain intracellular reduction of
CTC to the insoluble fluorescent formazan (CTF) product, which was
indicative of cellular RESPIRATORY activity.)
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Mikhail Vainshtein
Curator of bacteria of VKM; IBPhM, Russ.Acad.Sci., Pushchino.
Assistant Professor, Pushchino State University.
