Biofuels production from solid and liquid fractions of hydrothermally pretreated sugarcane bagasse in a continuous compartmentalized reactor and potential metabolic pathways

Solid and liquid fractions of hydrothermally pretreated sugarcane bagasse (SCB) were simultaneously used as substrate of a novel continuous compartmentalized reactor. The effect of four (56, 42, 28, and 14 hours) hydraulic retention time (HRT) and chemical oxygen demand (COD) (0.5, 3.0, and 9.0 g/L) were evaluated on hydrogen (H 2 ) and organic acids production. Higher H 2 production and yield (686 mL and 1.63 mol/mol consumed carbohydrates, respectively) were obtained at HRT of 28 h, probably due to the Clostridium and Thermoanaerobacterium metabolisms, which accounted for almost 60% of the microbial relative abundance. Under lower and higher HRT (14 and 56 h, respectively) lactic acid predominated without hydrogen production. Other value-added chemical such as citric, valeric and caproic acids were also obtained as a function of HRT. From the functional point of view, enzymes from the glycoside hydrolases group (GHs) potentially performed important role in the lignocellulosic biomass bioconversion.