anaerobic bioreactor Metagenome

Sugarcane bagasse (SCB) was used as a lignocellulosic substrate and glucose as control, combining the co-production of H2 (Stage 1) and CH4 (Stages 2 and 3) by a three-stages anaerobic fermentation process in batch reactors. In addition, 2-bromoethanesulfonic acid (BES) was used in the first stage to optimize H2 production by inhibiting the methanogenic archaeas, as well as a hydrothermal (200 ° C, 20 bar, 10 min) associated with the enzymatic (Aspergillus niger) pretreatment of SCB was applied. Two fermentative inocula (In 1 and In 2) were used in stage I and a methanogenic inoculum in stages 2 and 3 (In 3). Three experimental series were performed: A (In 1), B (In 1 plus In 2) and C (In 2). The final metabolites from stage I were transferred to a second reactor for the subsequent methane production stage (Stage II). Finally, the final metabolites from Stage II were transferred to a third reactor for the next phase of methane production (Stage III). Stages II and III were inoculated with In 3. The higher H2 yield was in C stage I (4.3 and 38.5 mmol H2/g substrate for SCB and glucose, respectively). Moreover, the higher CH4 yield was obtained in the stage III for C (6.3 and 18.2 mmol CH4/g substrate for SCB and glucose, respectively). For all conditions the H2 production occurred primarily via acetic acid. Predominance of Enterococcus and Clostridium that produce cellulolytic enzymes may favored the H2 production from SCB and subsequent CH4 production mainly from members of Methanoregulaceae and Methanosaetaceae Families. Furthermore, the development of homoacetogenic bacterias (Acetobacterium, Clostridium, Eubacterium, Holophaga) was observed in the reactors. These microbial groups acted in synergism for the hydrolysis of SCB and hydrogen and methane production.