MAINTENANCE OF YEASTS BY FREEZE-DRYING

Abstract

Eighty-three yeast cultures representing 12 genera have been freeze-dried and the preparations examined for viability, fermentation reactions and vitamin requirements after 2 days and again after storage for 9 months. The results showed that, although freeze-drying itself led to considerable loss of viability, subsequent storage for 9 months had little further adverse effect on the cultures. The fermentation reactions of all the strains examined remained unaltered, although variations in vitamin requirements were observed. The method of interpreting the results of the vitamin requirement test is discussed in the light of the finding that the failure of growth to reach an arbitrary level at 24–48 hr. may be misleading.