Mechanisms of Damaging Bacteria during Lyophilization and Protective Activity of Shielding Media

Abstract

Considered are the current views on the mechanisms and factors of bacterial cell degradation during lyophilization and storage of dry preparations. Given are the data on the most effective lyo-rotectors and mechanisms of their shielding action. Lyophilization or sublimation from the frozen state is the basic method of bacteria preservation in culture collections and biological resource centers. In the process of lyophilization cells are exposed to damaging stress factors. Low temperatures, water crystallization, osmotic process, pH alterations, and dehydration affect cell cultures and molecules. Oxidative reactions, running in dry cell preparations, change the composition and structure of lipids, proteins, nucleic acids, and, thereby reduce the number of living cells during the storage. One of the key factors that influences bacterial viability after lyophilization and storage is the composition of shielding medium, with which the cells are mixed up before conservation. Utilization of protective media, containing carbohydrates, amino acids, restored milk, gelatin and other components, decreases the probability of cell elements damaging and extends the assured storage life.

Keywords

• lyophilization
• bacteria
• culture collections
• shielding media
• viability
• damage