TBX medium is prepared based on Tryptone Bile Agar medium. Tryptone bile agar is a primary method for identifying E. coli in food samples. One of the advantages of this medium is its speed, reliability, better recovery of microorganisms from frozen samples, and identification of microorganisms with low lactose fermentation.
The TBX medium, in addition to the advantages of Tryptone Bile Agar medium, contains the chromogenic substrate X-Glucuronide. This substrate has a high specificity for E. coli in a way that only 3-4% of E. coli bacteria are without the hydrolyzing enzyme of this substrate. One of them can be mentioned as E. coli O157.
E. coli bacteria can absorb this compound and their intracellular enzymes can hydrolyze the bond between glucuronide and chromophore. The separated chromophores are colored and cause E. coli colonies to appear blue-green.
Preparation
- Weigh 36.6 grams of the powder and dissolve it in 1 liter of distilled water.
- Autoclave at 121°C for 15 minutes.
- Wait until the medium reaches a temperature of 45-50 degrees Celsius and pour it into sterile Petri dishes.
STORAGE
- Keep the dehydrated powder and the prepared medium stored at a temperature of 2-8 degrees Celsius.
