Heat Effects for a Single Cell of Saccharomyces cerevisiae Determined using a Classic and a New Procedure
1997 年 24 巻 3 号 p. 111-117
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1997 年 24 巻 3 号 p. 111-117
The growth thermograms observed with a multiplex isothermal calorimeter during growth at 30°C were employed for the determination of various parameters characterizing the growth and heat production of a Saccharomyces cerevisiae strain. The heat evolution curve, cell number curve and ethanol production curve determined for the yeast culture were found to be correlated, and the values of the growth rate constant μ determined from these curves were, respectively, 0.37, 0.34 and 0.32h-1. From the correlation existing between the heat evolution curve and the cell number curve, an average heat evolution Q=(1.35±0.02)×10-7 J cell-1 and a corresponding q1=20±3pW cell-1 for the average heat evolution rate for a single cell were determined. Similar considerations allowed the determination of the average heat amount (QE=147.6kJ mol-1) and the average number of yeast cells (NE=1.09×1012 cell mol-1) associated with the production of one mole of ethanol. On the second hand, a new method was proposed for the determination of the average heat evolution rate per cell, which requires only the knowledge of the initial number of cells (the inoculum size) and the selection of an arbitrary level α on the time derivative of the heat evolution curve observed for the yeast culture. The values of q1 determined using this method were found to depend on the level α, but the average was q1=28.0±2.4pW cell-1, which is relatively close to the value determined by the classic method.
