A conventional baker's yeast strain D incorporated trehalose into its cells from a YPG medium supplemented with trehalose. Cells cultured in a medium containing 3 to 5% trehalose increased to nearly 5 times the trehalose content of cells cultured in the absence of trehalose. After 1 day of frozen storage at -20 °C, cells cultured in 3% trehalose medium experienced a lesser decrease in both viability and CO2 productivity than cells cultured in the absence of trehalose. Even after 10 days frozen storage, the strain D cultured in the 3% trehalose medium retained to nearly 50% of the viability and CO2 productivity of the unfrozen cells. Although the freeze-tolerant yeast strains DFT and S. cerevisiae MAFF 10-03056 showed, during freezing, smaller decreases in viability than strain D, the large decreases in CO2 productivity were comparable among all three strains. The CO2 productivity in both freeze-tolerant strains cultured in the presence of 3% trehalose was about 60% of that in the unfrozen cells, even after 10 days of frozen storage. The CO2 productivity and actin content of the cell-free extracts prepared from the strain D cultured in YPG medium decreased significantly to about 15% and 30% of those of the unfrozen cells, respectively, after 7 days of frozen storage. When the cells cultured in the presence of 3% trehalose were frozen-stored, the CO2 productivity of the cell-free extracts prepared from 7-days frozen-stored cells decreased to 50% of that from the unfrozen cells. The actin content, however, did not decrease after the same frozen storage. In eukaryotic cells, the activities of some glycolytic enzymes are increased by association with actin. It seems that the native structure of actin is necessary for yeast CO2 productivity after frozen storage.
|Number of pages||8|
|Journal||Journal of the Faculty of Agriculture, Kyushu University|
|Publication status||Published - 1996|
All Science Journal Classification (ASJC) codes
- Agricultural and Biological Sciences (miscellaneous)