Agar is a jelly-like substance obtained from red algae, used heavily as a solid medium for growing various microbes. Many specific formulations are available because some microbes prefer certain environmental conditions over others.

Columbia Agar - for the cultivation of fastidious microorganisms.

Preparation:

1. Disperse 41 g in 1 L of deionized water.
2. Soak for 10 minutes, swirl to mix, and sterilize by autoclaving for 15 minutes at 121oC.
3. Cool to 47oC and add 5-7% of defibrinated blood.
4. Mix before pouring into dishes and then dry the agar surface.

Typical g/L

pH: 7.3 ± 0.2

Columbia Peptone Mixture 23.0, Corn Starch 1.0,

Sodium chloride 5.0, Agar No. 2 12.0