[Characteristics of free water distribution in the cytoplasm of cryotolerant cells of Cryptococcus laurentii].

The resistance to freezing-thawing was studied with Cryptococcus laurentii cultivated at a near-zero plus temperatures in a minimal or a rich medium. At the transition into the stationary phase, the resistance of the cells to freezing increased 20 times in the culture grown in the minimal medium and 8 times in the culture grown in the rich medium. Free water localization in the cell cytoplasm was determined by electron microscopy. In yeast cells with the maximal cryotolerance, free water was found mainly between glycogen granules. The authors discuss the role of glycogen as of a possible factor making the cells resistant to low temperatures.