Metataxonomic characterization of an autochthonous and allochthonous microbial consortium involved in a two-stage anaerobic batch reactor applied to hydrogen and methane production from sugarcane bagasse.

Enzymatically pre-treated sugarcane bagasse (SCB) was used as substrate for sequential production of hydrogen (H) and methane (CH). In stage I, SCB was used by autochthonous bacteria, such as Enterococcus (42.4 % relative abundance) and Paraclostridium (16.8 %) for H production (166.8 mL H/L), while the metabolites accumulated at the end of this stage (9140.5 mg HAc/L) were used by allochthonous inoculum for CH production (870.8 mL CH/L) in stage II. In stage II, hydrogenotrophic (Methanoculleus, 49.1 %) and acetoclastic (Methanosaeta, 15.5 %) archaeal genera were identified and considered important to maintain low H pressure in the system. According to gene inference, the hydrolysis of the SCB fiber was performed in both stages, as potential β-glucosidase and 1,4-β-xylosidase encoding genes were predicted. However, the energy metabolism of microbial populations differed, as potential genes involved in CH metabolism were predominant in phase II (39.0 %).