Viability of the F strain of Mycoplasma gallisepticum after storage in the frozen or lyophilized state.

Strain F of Mycoplasma gallisepticum was stored frozen at -60 C or -20 C in liquid medium with or without cryoprotective agents or was lyophilized with or without stabilizers and stored at 4 C. The titer was determined before, during, and after the subsequent storage period. In cultures frozen at -60 C or lyophilized, the titer had not significantly declined by the end of 371 days of storage. At -20 C, the titer of frozen cultures declined rapidly, and no mycoplasma had survived 282 days of storage. The addition of cryoprotective agents (10% glycerol or 8% dimethyl sulfoxide) or freeze-drying stabilizers (12% sucrose, or 7.5% glucose, 8% skim milk, or SPA) did not help maintain the viability of the mycoplasmas during freezing or freeze-drying process and the subsequent storage.