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Abstract: Well defined microbial strains for usage in science and industry can only be obtained after a large investment in kncwledge, time and equipment. It is one of the major tasks of service culture collections like the DSM to keep these - not only scientifically - valuable cultures for a long period and as unchanged as possible. In the case of basidianycetes, which nostly lack vegetative propagules, this task has beccme possible only after the development of low tenperature storage methods of mycelia in liquid nitrogen (LN2). The ultrastuctural changes during the freezing and thawing of living cells are highly ccnplex and far frcm being fully understood. Since the chance detection of the cryoprotective action of glycerol about 40 years ago many technical problems of LN2-preservation have been solved but still a lot of them remain. A recent discussion can be found in Withers (1980). Different protocols have been published for the LN2-preservation of living cells (Kirsop and Snell 1984, Smith and Onions 1983), varying with equipment, special needs, preference of materials or the type of organism under study. We considered the following facts nost important: 1. universal applicability for a wide range of organisms 2. stock for several years at minimal storage volume 3. protection for the user (no glass, no sealing). Based on these premises and following suggestions by Dietz (1975) and Elliott (1976) we developed a procedure that is very rapid – a culture is processed in 15 t o 30 minutes – and that has now been successfully applied to several hundred basidicnycetes and more than 1 500 strains of other fungi and yeasts.
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