The results summarized in Table 3 show that the highest
xylitol production (16.20 g L−1) and volumetric productivity
(0.34 g L−1 h−1) were obtained in the experiment with
increased initial oxygen availability and full supplementation.
This is consistent with the highest cell concentration also
found in this experiment but not with the xylitol yield, as
discussed previously (Table 3). These results suggested that,
even though the control of oxygen availability is a critical factor
on xylose-to-xylitol bioconversion, it may be possible to
improve this bioprocess, particularly the volumetric productivity,
by increasing xylose consumption under conditions of
oxygen limitation. Another possibility to consider would be
the use of conditions favoring of cell growth in a previous
phase, before the xylose-to-xylitol bioconversion begins. In
comparison with the above-mentioned studies, which used
other lignocellulosic biomasses but the same yeast and similar
fermentation conditions, the highest xylitol volumetric
productivity obtained in this study (0.34 g L−1 h−1) was higher
than the one reported by Sene and colleagues36 (0.19 g L−1 h−1)
and lower than those obtained by Arruda and colleagues35
(0.60 g L−1 h−1), Marton and colleagues25 (0.50 g L−1 h−1), and
Mussatto and Roberto21 (0.57 g L−1 h−1).