I am trying to use plate count to enumerate glycerol stocks of anaerobic bacteria without success. Its unclear why and I'm hoping someone can help.
Cells were prepped as follows:
1. Organisms grown to OD600 0.5-1 (approx. 1E8 CFU/ml, previously validated by plate count) in preferred culture medium.
2. An aliquot is removed and 10-fold serial dilutions in reduced 0.9% NaCl are plated.
2. Cells are pelleted and the broth removed.
3. Cells are resuspended in reduced phosphate buffered 15% glycerol and the OD rechecked.
4. 10-fold serial dilutions are plated on culture medium/agar plates.
Plate count from culture: approx. 1E8
OD600 from glycerol: 0.5-1
Plate count from glycerol: No growth
The glycerol stocks were successfully used for bioreactor inoculation.
I'm surprised at this result, and it's happened with several different organisms.
Any comments/thoughts are appreciated.