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Tryptose Sulfite Cycloserine agar

The figure shows three TSC agar plates, where no bacteria have been cultivated on plate A. Clostridium perfringens has been cultivated on plates B and C. Plate C contains lecithin, but not plate B. Note the precipitation zone of diglycerides around the colonies on plate C.- Click on the image to enlarge it.

Image: Ingrid Hansson (SLU), Lise-Lotte Fernström (SLU) & Karl-Erik Johansson (SLU).

Applications:

Tryptose Sulfite Cycloserine agar (TSC agar) is used for isolation and enumeration of both vegetative cells and spores of Clostridium perfringens in food and clinical samples.

The medium contains:

meat peptone (contains amino acids and peptides)
soya peptone (contains amino acids and peptides)
yeast extract
ammonium ferric citrate (see below)
sodium disulfite [is reduced to sodium sulfide (by some bacteria), which forms a black precipitate (FeS) with ammonium ferric citrate]
lecithin (optional)
cycloserin (inhibits the background flora of bacteria)
agar (gelifying agent)
water

The final pH of the medium should be 7.6.

Other comments:

Hydrogen sulfide (H₂S) positive bacteria (as e.g. C. perfringens) form black colonies on TSC agar. If the TSC agar contains lecithin, a precipitation zone will be formed around colonies, which produce lecithinase.

Updated: 2019-06-11.

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Tryptose Sulfite Cycloserine agar

Applications:

The medium contains:

Other comments:

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