Sterilization of culture media containing serum is by

[Medicoman]

Sterilization of culture media containing serum is by-

• 1. Autoclaving
• 2. Micropore filter
• 3. Gamma radiation
• 4. Centrifugation

exp:

Sterilization of culture media

• The constituents of culture media must be carefully sterilized.

• Two methods are commonly used to sterilize culture media -

1. Autoclaving

• Constituents like water, salts and supplements like peptone, tryptose etc., which are heat stable, are autoclaved.

• Generally autoclaving is carried out at 121°C and at a pressure of 15 psi.

• The time required for sterilization depends upon the volume of medium in the vessel-

1. For small volumes of liquids (100 ml or less), the time required for autoclaving is 15-20min.
2. For large quantities (2-4 liter) 30-40 min is required.

2. Membrane filtration

• Constituents like serum, trypsin, growth factors, proteins, amino acids, vitamins, hormones, carbohydrates and plant extracts are thermolabile and may decompose during autoclaving.

• These must be sterilized by filtration.

• The porosity of the filter membrane should be no longer than 0.2 microns (U m). - Empty glassware that is to hold media must be sterilized in an autoclave before filter sterilization.

• These two ( autoclaving and membrane filtration) are the most commonly used methods for sterilization of culture media. But when these are not available other methods can be used; e.g.-

• For media containing sugar or gelatin, an exposure of 100°C for 20 minutes on three successive days may be used. This is known as Tyndallization.

Some media containing serum or egg fluid can be sterilized by heating to 80-85°C for 2-4 hours.