Molecular Studies as a Guide for Designing an Optimal Lyophilization Process for Microbial Preservation

Storage of microorganisms in a quantitative format is essential for modern industrial quality control and other related applications. Lyophilization, or freeze drying, is one of the most widely used techniques for preserving microorganisms. However, lyophilization is a complex process that involves phase changes of the extracellular environment, and the outcome is highly influenced by the compositional, thermal, and pressure changes of the materials. During lyophilization, cellular stress creates changes in the global protein profile and might also cause genetic variability. We have used global proteomic analysis (LC-MS/MS) and next-generation sequencing to evaluate the impact of lyophilization on the viability of microorganisms. In this study, we used Escherichia coli (ATCC 8739) as a model organism to evaluate how changes in the lyophilization formulation affect protein expression characteristics. Our findings underscore the need to use a proper lyophilization formulation and profile for optimum viability and less genetic variability.