A STUDY OF THE EFFECTS OF STORAGE TEMPERATURE AND THAWING METHODS ON THE LONG-TERM PRESERVATION OF SELECTED STRAINS OF MICROORGANISMS AND MAMMALIAN CELLS.
AMERICAN TYPE CULTURE COLLECTION ROCKVILLE MD
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The objective of this study was to determine the effects of temperature of storage and thawing on the viability of microorganisms and mammalian cells frozen for long periods. Test strains were Syzygites megalocarpus, ATCC 11807, Penicillium megasporum, ATCC 12322, Vibrio cholerae, ATCC 12174, Staphylococcus aureus, ATCC 6538, and derivatives of strain L mouse connective tissue cells, NCTC clone 929, ATCC-CCL 1, and human skin epithelial cells, NCTC 2544, ATCC-CCL-19. Quantitative tests for viability were made prior to freezing, within 24 hours after freezing, at the end of three months, at the end of one year, and at yearly intervals for five years. Thawing was carried out directly from temperature levels higher, lower, or the same as the temperature of storage. For fungi and animal cell lines, storage at -196C was vastly superior to storage at -20C and -79C. For bacteria, storage was almost as effective at -79C as at -196C -20C storage was less effective. Experiments at both 3-month and 12-month storage periods indicated that there is no advantage to thawing the cells from temperatures lower or higher than the temperature of storage. The results indicate that when cells are frozen under similar controlled conditions the storage temperature level per se is the most critical factor in long-term preservation provided the cells are thawed rapidly. Author
- Medicine and Medical Research