TX Plates
TX (TA, TM, TG) Plates
Summary
2-3-5-triphenyl tetrazolium chloride (TTC) is a dye which turns red when reduced. Bacterial colonies that are expressing a certain biochemical activity can be identified by visual examination because they have a unique color on media containing a particular dye. In most cases the dye changes color when it is hydrolysed, or acts as a pH or redox indicator. TA (Tetrazolium Arabinose) are the most common plates used in this laboratory. We use TA agar for distinguishing Ara- and Ara+ strains in most competition assays. Colonies of Ara- strains typically appear red on TA agar, while those of Ara+ strains appear white/pink.
TX Agar
| INGREDIENT | 1000 mL Flask | 2000 mL flask | 2000 mL flask |
|---|---|---|---|
| Total volume of media | 500 mL | 1000 mL | 1500 mL flask |
| Tryptone | 5 g | 10 g | 15 g |
| Yeast Extract | 0.5 g | 1 g | 1.5 g |
| Sodium Chloride | 2.5 g | 5 g | 7.5 g |
| Agar | 8 g | 16 g | 24 g |
| Distilled water | 400 mL | 800 mL | 1200 mL |
TX Sugar
| INGREDIENT | 250 mL Flask | 250 mL flask | 500 mL flask |
|---|---|---|---|
| Total volume of media | 500 mL | 1000 mL | 1500 mL flask |
| Sugar* | 5 g | 10 g | 15 g |
| Distilled water | 100 mL | 200 mL | 300 mL |
*Sugar can be Arabinose (TA), Maltose (TM) or Glucose (TG).
- Prepare media in desired volumes.
- Carefully add a stir bar to flask and mix ingredients. Leave stir bar in while autoclaving.
- Autoclave on a liquid load for at least 45 minutes.
- After autoclaving, let cool to about 55°C (you should be able to place the back of your hand against the flask for a few seconds without it feeling too hot), add the arabinose and 1mL of sterile 5% TTC per liter of media and pour plates. Note: Plates should be poured immediately although agar can temporarily be stored in the 55°C oven. This should be avoided if possible due to potential bacterial contamination.
- Pour the plates.
- Allow Petri dishes to solidify for ~24 hours on the bench top before storing in the walk-in fridge. Cover the solidifying Petri dishes with a box or black garbage bag because TTC is light-sensitive.
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Original Recipe by: C. Eshelman Date: 26 July 12
Recipe Updated by: ___ Date: ___