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What is tryptone Broth test?

What is tryptone Broth test?

Tryptone Broth is used for the detection of indole production by coliforms. Suspend 15 grams in 1000 ml distilled water. Heat if necessary to dissolve the medium completely. Dispense into tubes and sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes.

How do you prepare tryptophan Broth for indole test?

Dissolve 16g Tryptophan Broth in one liter water by heating. Dispense 3 ml per test tube. Close the tubes with cotton plugs, plastic or metal caps. Autoclave for 15 min at 121 +/- 3°C.

How do you make tryptone Broth?

What is the purpose of tryptone Broth?

Tryptone Broth, also known as T-broth, is a moderately rich, general-purpose medium that is used for growing Escherichia coli. The broth contains tryptone to provide the basic nutrients and growth factors needed to support bacterial growth.

Is tryptone broth selective?

This is a non-selective medium, useful for the cultivation of a variety of microorganisms.

How do you perform a tryptone broth test?


  1. Obtain a tube of tryptone broth.
  2. Using an inoculating loop, swish some of your assigned organism in the broth.
  3. Incubate the tube for at least 48 hours.
  4. After the incubation period, add several drops of Kovac’s reagent to the tube.

Why is tryptone broth used in indole test?

As some bacteria digest tryptophan, one product sometimes produced is indole, a compound responsible for the smell of feces. Tryptone broth is frequently used for the indole test, important for identifying enteric bacteria. If indole is produced, it will accumulate in the culture tube during a 24-hour incubation.

Is E. coli indole positive?

Indole production is often used to differentiate E. coli from other indole-negative enteric bacteria because 96% of E coli are indole positive, whereas many enterobacterial species are negative in the indole reaction.

Does tryptone broth contain carbohydrates?

Tryptone is used in microbiology to culture bacteria. As well as being rich in nitrogen, vitamins, and amino acids, and therefore good for bacteria to grow on, the product contains tryptophane and has very little carbohydrate content.

Is malonate broth selective or differential?

The Malonate Test was originally designed to differentiate between Escherichia and Enterobacter. Its use as a differential medium has now broadened to include other members of Enterobacteriaceae.

What is the difference between nutrient agar and nutrient broth?

The main difference between nutrient agar and nutrient broth is that nutrient agar is a solid medium whereas nutrient broth is a liquid medium. Agar is added to the nutrient agar in order to solidify the medium. Nutrient agar is prepared in Petri dishes while nutrient broth is prepared in test tubes or bottles.

Is E. coli oxidase positive?

E. coli bacteria are among the few species of lactose (LAC)-positive, oxidase-negative, gram-negative rods that are indole positive.