3.2. Preliminary BC production essays with DOR
residues
The water extracts were then autoclaved and tested as carbon
sources in BC production without the addition of any other
nutrients. The results obtained (Fig. 1), showed BC productions
of 0.81 ' 0.04 g L"1 for DOR40 and 0.85 ' 0.04 g L"1 for
DOR100, which corresponded respectively to 32 and 34% of the
production achieved with conventional HS culture medium
(w2.5 g L"1
). Finally for DOR100H, despite the higher amounts
of monosaccharides available, there was no BC production,
which was certainly due to the formation or release of organic
compounds such as furfural during the hydrolysis step,
resulting from sugar degradation and also phenolic compounds,
which could have inhibited the metabolism of G.
sacchari and consequently BC production [3]. So, unless laborious
processes for inhibitors removal are used, the hydrolysed
aqueous extract DOR100H is not suited for BC
production. However, the BC production values obtained for
the two aqueous extracts DOR40 and DOR100 are already
promising as these are considerably higher than those previously
reported for other residues [22]. Based on these preliminary
results it was decided that the optimization studies
would be carried out with the DOR40 aqueous extract because
its preparation requires less energy consumption to obtain
similar results of BC production.