초록
<P><B>Abstract</B></P> <P>The individual and mutual effects of substrate concentration (from 0.8 to 9.2 g/L) and pH (from 4.6 to 7.4) on hydrogen and volatile fatty acids production from sugarcane bagasse (SCB) were investigated in batch reactors, using a response surface methodology (RSM) and central composite design (CCD). The maximum of 23.10 mmoL H<SUB>2</SUB>/L was obtained under optimized conditions of 7.0 g SCB/L and pH 7.2, at 37 °C through the acetic acid pathway (1.57 g/L). Butyric and succinic acids were the major volatile fatty acids (VFA) produced in the fermentation process (from 0.66 to 1.88 g/L and from 1.06 to 1.65 g/L, respectively). According to the results, the RSM and CCD were useful tools to achieve high hydrogen production rates using <I>Clostridium, Bacillus</I> and <I>Enterobacter,</I> identified by Illumina sequencing (16S RNAr) in the fermentative consortium, and <I>Clostridium</I> and <I>Paenibacillus,</I> autochthonous bacteria from SCB. Significant changes were observed in the microbial community according to the changes in the independent variables, since the genera in the central point condition (5.0 g SCB/L and pH 6.0) were <I>Lactobacillus</I>, <I>Escherichia</I> and <I>Clostridium,</I> and <I>Bacteroides</I> and <I>Enterobacter</I>, which were identified in the optimized condition (7.0 g SCB/L and pH 7.2).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Substrate concentration and pH effects on hydrogen production were investigated. </LI> <LI> A model of hydrogen production from sugarcane bagasse was validated. </LI> <LI> Significant changes in the bacterial community were observed. </LI> </UL> </P>