I can't figure out why my stock of bacteria are not growing. The bacterium, A. actinomycetemcomitans, was stored in a 1 mL 20% glycerol microcentrifuge tube and placed in the freezer. But before I put it into the freezer I forgot to mix the pellet of bacteria thoroughly with the glycerin. Could that be a problem?
In an attempt to determine the CFU's in the microcentrifuge tube, I performed serial dilutions twice up to 10-6, 10-7, 10-8, 10-9. Incubation time was 24-48 hrs @ 37 degrees C. The first go around, there were too many bacteria on all the plates (probably due to contamination) and this second time there were no bacteria at all. What could be going on?
The serial dilutions were performed with 10X TBS.
Edited by stacker, 15 September 2011 - 08:57 AM.