Optimization of cryopreservation and lyophilization for demethylvancomycin producing strain—an assessment of 10-year preservation

Abstract:

[Objective] Due to the difficulties in preserving demethylvancomycin producing strain, we optimized the preservation conditions, and assessed the 10-year stability of different preservation methods with liquid nitrogen preservation, ?80 °C cryopreservation and lyophilization outcomes. [Methods] Using glycerol and skim milk as the basic protective agent for cryopreservation and lyophilization, the effect of cooling rate for liquid nitrogen cryopreservation and impermeability protective agents such as trehalose and polyvinylpyrrolidone (PVP) to these three preservation methods were studied. Ten years tracking assessment on optimal preservation method was performed. [Results] Among the three preservation methods, ?80 °C cryopreservation showed the highest survival rate for demethylvancomycin producing strain, followed by liquid nitrogen cryopreservation and lyophilization. The optimum cooling rate for liquid nitrogen cryopreservation was rapid freezing, and the optimum protective agent was as follows: 8.0% glycerol with 3.5% trehalose for liquid nitrogen cryopreservation, 6.0% glycerol with 5.0% PVP for ?80 °C cryopreservation, skimmed milk with 6.0% trehalose for lyophilization. The 10-year survival rate of liquid nitrogen preservation reached 70.6% through optimum preservation condition, productivity of demethylvancomycin remained 92.9% of the original level. [Conclusion] Under optimum preservation condition, liquid nitrogen cryopreservation is suitable for long-term preservation.