|Budget Amount *help
¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1993 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1992 : ¥1,100,000 (Direct Cost : ¥1,100,000)
In the presence of relatively low concentrations of ethanol, small aquatic animals such as tadpoles sink to the bottom of a water tank, but they begin to swim when a pressure of about 20 Mpa is applied. This phenomenon of recovery from an anesthetized state on application of pressure is known as pressure reversal of anesthesia and is the reason why pressure is often used to investigate the mechanisms of action of anesthetics. This phenomenon has also been observed with some microorganisms. On application of pressure to suspensions of E.coli containing a few per cent of ethanol, survival of the cells increases with increase in pressure up to 10-20 Mpa.
Yeast produces ethanol from glucose and this product should act an anesthetic on the cells. Accordingly, the growth of yeast should gradually be retarded and some cells should die with the progress of fermentation. If pressure is applied to this system, survival of yeast should be greater than at atmospheric pressure. Therefore, as an application of this phenomenon, we examined the pressure reversal for survival of yeast and examined the fermentation of glucose by yeast at high pressure.
Pressure revesal of anesthsia was applied to alcoholic fermentation of glucose by yeast. The survival of yeast in the absence of ethanol decreased with increase in pressure. However, in medium containing 4 and 8%(w/w)ethanol, cell survivals reached peaks at 20 MPa(200 bar). Although viable yeast cells apparently increased at a pressure of 20 MPa, no increase of the alcohol concentration was observed under the experimental conditions used.