f Damage and Survival of Bacteria during Freeze-Drying and during Storage over a Ten-Year Period

SUMMARY: Extrapolation from 10-year survival curves indicates that many lyophilized bacterial suspensions may be expected to yield viable organisms after centuries of storage, but that suspensions of Pseudomonadaceae may become sterile within one to several decades. The characters of Lactobacteriaceae and other bacteria appear unaltered as a result of lyophilization and storage for 5 years, but some Bacteroides isolates manifested apparently altered fermentation reactions under the same circumstances. Freezing bacteria in pellets is suggested as an alternative method of storage for those species which are particularly sensitive to lyophilization.