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 pro- ductions 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 com- pounds, which could have inhibited the metabolism of G. sacchari and consequently BC production [3]. So, unless labo- rious processes for inhibitors removal are used, the hydro- lysed 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 previ- ously reported for other residues [22]. Based on these pre- liminary 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.