Biohydrogen production using xylose or xylooligosaccharides derived from sugarcane bagasse obtained by hydrothermal and acid pretreatments.

The employment of hemicellulose fractions from bagasse acid (HF-AC - rich in xylose) and hydrothermal (HF-HT - containing high amounts of xylooligosaccharides) pretreatments led to yields of 265 and 177 mL H2 /g carbohydrate after 18 and 45 h of fermentation, respectively. The anaerobic sludge used as inoculum was able to hydrolyze the xylooligosaccharides of HF-HT into simpler sugars, enabling microbial hydrogen production. The acid hydrolysis of xylooligosaccharides in HF-HT before fermentation improved the productivity by 30% and showed similar yield (231 mL H2 /g carbohydrate). The adaptive phase for HF-HT consumption was influenced by the hydrolytic step and by inhibitors, as the kinetics of hydrolyzed HF-HT was deeply affected in the first 18 h compared to HF-AC. Higher amounts of HF-AC in the media promoted fermentation inhibition, which could be related to the increased concentrations of acetic acid and carbohydrates, two factors that enhance the system osmolarity. Image 1 • C5 fractions from acid or hydrothermal pretreatment of sugarcane bagasse were used. • Oligosaccharides were hydrolyzed into simpler sugars by the anaerobic sludge. • Hydrolytic step and inhibitors influenced the hydrothermal C5 fraction consumption. • Total osmolarity of the fermentative media plays a role in H 2 production inhibition. [ABSTRACT FROM AUTHOR]