Enhanced glycerol production in Shochu yeast by heat-shock treatment is due to prolonged transcription of GPD1

Enhancement of glycerol production in Shochu yeast, which was induced by he at-shock treatment, was studied. Although heat-shock treatment (45 degrees C, 1 h) caused a transient delay in cell growth, the amount of glycerol pro duced by heat-shock-treated cells was 20% higher than that by control cells . During the glycerol-production phase, the NAD(+)-dependent glycerol-3-pho sphate dehydrogenase (GPDH) activity of heat-shock-treated cells was much h igher than that of control cells, suggesting that a higher GPDH activity en hances glycerol production. The level of NAD(+)-dependent glycerol dehydrog enase (GDH) activity was almost the same between heat-shock-treated cells a nd control cells. The results of Northern blot analysis of GPD genes (GPD1 and GPD2) encoding the GPDH enzyme showed that the transcription of GPD gen es was not affected by heat-shock treatment but the period of intensive tra nscription of GPD1 was prolonged.