Aspergillus niger growth on SEB. A. niger conidia were grown for 24 hours on batch cultivation medium without yeast extract supplemented with 0.5% steam-exploded sugarcane bagasse as carbon source. (A) Steam-exploded sugarcane bagasse (SEB) fragments stained with toluidine blue without any inoculation (left panel) and inoculated with A. niger and grown for 24 hours at 30°C (right panel). (B) Magnification of SEB inoculated with A. niger for 24 hours at 30°C. Bars = 20 μm.