Ethanol production by K. marxianus in whey
from organic cheese production was examined in batch and
continuous mode. The results showed that no pasteurization
or freezing of the whey was necessary and that
K. marxianus was able to compete with the lactic acid
bacteria added during cheese production. The results also
showed that, even though some lactic acid fermentation
had taken place prior to ethanol fermentation, K. marxianus
was able to take over and produce ethanol from the
remaining lactose, since a significant amount of lactic acid
was not produced (1–2 g/l). Batch fermentations showed
high ethanol yield (*0.50 g ethanol/g lactose) at both
30C and 40C using low pH (4.5) or no pH control.
Continuous fermentation of nonsterilized whey was performed
using Ca-alginate-immobilized K. marxianus. High
ethanol productivity (2.5–4.5 g/l/h) was achieved at dilution
rate of 0.2/h, and it was concluded that K. marxianus is
very suitable for industrial ethanol production from whey.