Thioglycolate broth | Principle | Preparation | Interpretation


☰ Content :

Ⅰ. Overview

Ⅱ. Preparation / composition

Suspend the components, dehydrated powder, in water (29g in 1000ml of purified/distilled water). Bring to a boil and completely dissolve the medium.
Distribute in test tubes and sterilize in an autoclave at 121°C for 15 minutes.

Enriched versions of this medium also contain vitamin K1 and hemin.


Ⅲ. Principle



Ⅴ. Interpretation

◈ No turbidity: no growth

◈ Turbidity: growth (presence of organisms)

Thioglycolate broth

1: Obligate Aerobes need oxygen because they cannot ferment or breathe anaerobically. They congregate at the top of the tube where the oxygen concentration is highest.

2: The obligate anaerobes are poisoned by oxygen, so they congregate at the bottom of the tube where the oxygen concentration is lowest.

3: Facultative anaerobes can grow with or without oxygen because they can metabolize energy aerobically or anaerobically. They mainly congregate at the top because aerobic respiration generates more ATP than either fermentation or anaerobic respiration.

4: Microaerophiles require oxygen because they cannot ferment or breathe anaerobically. However, they are poisoned by high concentrations of oxygen. They congregate at the top of the test tube, but not at the very top.

5: Aerotolerant organisms do not need oxygen because they metabolize energy anaerobically. Unlike obligate anaerobes, however, they are not poisoned by oxygen. They can be found evenly distributed throughout the test tube.