Effect of Freeze-Drying on the Viability Of Selected Anaerobic Microorganisms

The viability of ten strains of anaerobic bacteria following freeze-drying in single strength skim milk, double strength skim milk, and sucrose broth was assessed over a period of one year. The eight genera included in the study were: Clostridium, Propionibacterium, Bifidobacterium, Eubacterium. Bacteroides, Fusobacterium, Peptococcus, and Peptostreptococcus. The following conclusions were drawn: 1) spore formers appeared to maintain higher viability counts than did non-spore formers: 2) viability counts were marginally dependent on the aerotolerance of the anaerobe: 3) gram-positive organisms apparently maintained higher counts than gram-negative organisms; and 4) sucrose broth maintained higher viability counts than either skim milk media