The simplest way to test for contamination is to incubate the prepared sample media At 35-37 OC for 24 hours. Turbidity in fluid media and microbial growth in solid media confirm contamination.
3. Addition of heat-sensitive ingredients Refrigerated-heat sensitive ingredients should be warmed at room temperature before added to a molten agar medium. Using an aseptic technique, the ingredients should be added when the medium has cooled to 50 OC, and should be distributed immediately unless further heating is required.
4. pH testing The pH of most culture media is near neutral, and can be tested using pH papers or pH meter.
5. Dispensing of culture media Media should be dispensed in a clean draught-free room using aseptic technique and sterile container.
Dispensing agar media in petridish
Lay out the sterile petridishes on a level surface.
Mix the medium gently by rotating the flask or bottle.
Flame sterilize the neck of flask or bottle.
Pour 15 ml of medium in each petridish.
Stack the plates after the medium has gelled or cooled.