Dilution strategy to obtain H2 in the 2nd acidogenic phase from enzymatically pre-treated sugarcane bagasse

Sugarcane bagasse (SCB) pre-treated with laccase was used as substrate in two acidogenic phases (1 P and 2 P). In 1 P, the pretreatment conditions were statistically optimized (pH 4.0, 37 °C, 0.4 U of laccase/mL, 24.0 g SCB/L and 120 min of reaction), which allowed obtaining 84% more H2 (166.8 mL/L) than SCB in natura (90.4 mL/L). In 2 P, the liquid fraction of the 1 P reactors was diluted (90%) and more 108.5 ml H2/L was obtained. Furthermore, the quantification of enzymes genes responsible for the hydrolysis (Cel) and H2 production (Hyd) was carried out. An increase in the expression of both genes was observed from the phase of highest H2 production rates in P1. In 2 P, the 1 P low genic expression was indicative of the autochthonous bacteria activity. The 2nd acidogenic phase strategy proved to be a promising novelty for the use of pre-hydrolyzed substrates with concomitant production of more value-added products.