malt extract for 2 days at 30°C with standing. The grown cells were
transferred into 10 ml of the juice, without supplementation of extra
nitrogen sources, in 15 ml-plastic tubes with 0.1%-inoculation.
The lids of the tubes were loosely tightened to avoid evaporation of
the ethanol produced and to remove the generated carbon dioxide
gas. After 5 days of cultivation at 30°C with standing, the ethanol
production, sugar consumption, yeast growth, and pH were measured.
As shown in Table 1, the strains of NBRC 0216 and Hitachi grew
well in the juice of FS902 and produced 5.70% (v/v) and 5.83% (v/v)
ethanol, respectively. The ethanol yields with both strains from FS902
were much higher than those from FS501 and KCS105, showing 85.0%
in strain NBRC 0216 and 86.9% in strain Hitachi. As total sugar in the
juice was consumed by around 98%, the sugar in the juice seemed to
be efficiently converted to ethanol. On the other hand, in FS501 and
KCS105 the yeasts did not grow sufficiently and the sugar consumption
was much lower than in FS902. The ethanol yields stopped at
around 15%, and even in the combination of NBRC 0216 and KCS105
which showed the highest value among them, the yield was 30.6%.
Thus, variety FS902 was the best carbon source among the three
varieties harvested in 2009, and both NBRC 0216 and Hitachi wer