LONG-TERM PRESERVATION OF YEAST CULTURES BY LIQUID-DRYING

Various selected strains from about 20 species of yeasts, which are re ported to be sensitive to freeze-drying and liquid-drying, were succes sfully dried directly from the liquid phase without freezing using a s implified liquid-drying method. All tested cultures proved viable and the majority of the tested strains showed good survival rates after dr ying. However, different survival levels for different yeasts were obs erved; generally the sensitivity to drying appeared to be strain-speci fic. After 1 years' storage at 9-degrees-C, no further loss in viabili ty was observed. Accelerated storage testing, for 1 week at 45-degrees , resulted in further loss of viability to various degrees. Yeasts tha t were filamentous, osmotolerant or psychrophilic appeared to be sensi tive to liquid-drying and had relatively lower survival levels than th e others. Growth and liquid-drying under microaerobic conditions resul ted in improved survival. The dried yeast cultures proved stable and n o mutation or loss in desirable characters was detected. The method ca n be used for the drying and long-term preservation of nearly all yeas t genera.