Aerobe-anaerobe test

Purpose

Determines oxygen usage in bacteria

Materials

• Thioglycollate broth (Difco)
• Test tubes (10x75mm) with vented caps

Instructions

1. Prepare thioglycollate broth as per manufacturer’s instructions
2. Dispense 8 mL into test tube (10x75mm)
3. Autoclave and store at 4°C
4. Boil tubes (in a beaker of water and boil chips) for at least 10 minutes to drive off O₂ prior to inoculation and cool to room temperature
5. inoculate tube with bacterium carefully- do not stir or shake tubes
6. Incubate at 25°C for 5 to 7 days
7. Observe the location of bacterial growth

• Aerobes will grow only at the surface of the broth (first few mm)
• Anaerobes will only grow in the lower portion of the tube
• Facultative anaerobes will grow at and below the surface of the broth and grow downward

1. Observe the color of media

• Pinkish is oxygenated
• Yellow is de-oxygenated

Notes

• Since bacteria vary in their O₂ requirements for growth, the types (aerobe, anaerobe, Fac. anaerobe) can be distinguished using a growth medium which ties up all O₂ in it, rendering the medium hostile to aerobes, except at the O₂ plentiful surface.

Contributed by

From the University of Florida Plant Disease Clinic-GNV mediabook: originally created by Gary Simone; contributed by Anne Vitoreli.