Proper preservation of strains is of great importance to all microbiologists. Working with contaminated or genetically changed cultures, or facing the loss of a strain are annoyances that often may be easily prevented. A reliable preservation method should fulfill the following criteria. First, the risk of introducing contaminants must be minimized. A method that invokes frequent subculturing is therefore considered less convenient. Such a method would also increase the risk of errors, including mislabeling and enrichment for mutants. Second, the cultures should be genetically stable during storage. Finally, loss of viability during preparation, storage, and reviving of the culture should be as low as possible. This guarantees a long shelf life and reduces the risk of selection for bacteria that are able to resist the exposure to stress conditions that occur during either processing or storage of cultures better.