2.4. Fermentation conditions
The fermentation was carried out at a temperature of 50 °C and
a pH of 5.0. The fermentation media, same as growth medium
except lower ammonium sulfate, 1.0 g l1
, prepared in glucoserich
hydrolysate and filtered through vacuum filtration using
0.2 mm Whatman GF/C filter paper, were fed into bioreactor at
different dilution rates. The pre-grown cells of Kluyveromyces sp.
IIPE453 in xylose-rich hydrolysate were used in the fermentation.
Approximately 60–70% cells were recycled into the bioreactor after
separating from the fermentation broth by gravitational settling in
a 1-L separating funnel. The steady state was attained after 12 h of
continuous operation at a dilution rate of 0.1 h1
.