Storage procedures for yeast preservation: phenotypic and genotypic evaluation

The aim of this study was to evaluate the morphological and biochemical characteristics of yeasts during storage. SixCandida spp. standard strains were stored in agarized medium with mineral oil in distilled water, frozen at ?70°C and freeze dried. Strains were phenotypically characterised before being stored and then periodically for up to 18 months. Randomly Amplified Polymorphic DNA (RAPD) was carried out in time zero, 6, 12 and 18 months of storage. The viability of all samples was preserved except for the strain ofCandida dubliniensis after 12 months of storage with mineral oil. No phenotypic alterations were observed in any of the methods employed. However, variations were observed in some phospholipase or proteinase activities. Changes in the RAPD patterns were not detected. These results seem to indicate that the maintenance methods tested were able to preserve the stability of the yeast phenotypic and genotypic characteristics.