BIOFUEL 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 h) hydraulic retention time (HRT) and three (0.5, 3.0, and 9.0 g L^-1) chemical oxygen demand (COD) levels were evaluated on hydrogen (H₂) and organic acids production. Higher H₂ production and yield (686 mL and 1.63 mol mol^-1 carbohydrate, respectively) were obtained under an 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 prevailed without hydrogen production. Other value-added chemicals such as citric, valeric and caproic acids were also obtained according to the HRT. From the functional point of view, enzymes from the glycoside hydrolases group (GHs) potentially performed important roles in the lignocellulosic biomass bioconversion.

Keywords:
biorefinery; building-block chemicals; hydrothermal pretreatment; lignocellulosic biomass; metagenomics analysis