Thermophilic hydrogen production from sugarcane bagasse pretreated by steam explosion and alkaline delignification

H2-production was evaluated using a microbial consortium from sugarcane bagasse in natura (SCBn) to ferment cellulose from pretreated SCB (SCBp; steam explosion and delignification alkaline). Six batch assays were performed: (1) 0.5 g/l SCBn + 0.5 g/l SCBp; (2) 2.0 g/l SCBn + 2.0 g/l SCBp; (3) 0.5 g/l SCBn + 0.5 g/l glucose; (4) 2.0 g/l SCBn + 2.0 g/l glucose; (5) 0.5 g/l SCBn; (6) 2.0 g/l SCBn. H2-production was verified in all assays; however, the SCBp influenced the H2-production, since that was verified a higher production. The higher H2-yield was in assay 1 (1.2 mol H2/g substrate). The metabolites produced were ethanol and acetic, butyric, iso-butyric, lactic and propionic acids. In assays 1, 2, 5 and 6, the H2-production occurred primarily via acetic acid. In assays 3 and 4, the main metabolite was butyric acid. Microorganisms identified were grouped into distinct phyla: Firmicutes, Bacteroidetes and Actinobacteria, with a predominance of genera Clostridium and Tepidimicrobium that produce cellulolytic enzymes favoring the H2-production from SCB.