초록
<P><B>Abstract</B></P> <P>The influence of different inoculum pretreatments (pH and temperature shocks) on mesophilic (37 °C) and thermophilic (55 °C) dark fermentative H<SUB>2</SUB> production from xylose (50 mM) and, for the first time, on the composition of the active microbial community was evaluated. At 37 °C, an acidic shock (pH 3, 24 h) resulted in the highest yield of 0.8 mol H<SUB>2</SUB> mol<SUP>−1</SUP> xylose. The H<SUB>2</SUB> and butyrate yield correlated with the relative abundance of <I>Clostridiaceae</I> in the mesophilic active microbial community, whereas <I>Lactobacillaceae</I> were the most abundant non-hydrogenic competitors according to RNA-based analysis. At 55 °C, <I>Clostridium</I> and <I>Thermoanaerobacterium</I> were linked to H<SUB>2</SUB> production, but only an alkaline shock (pH 10, 24 h) repressed lactate production, resulting in the highest yield of 1.2 mol H<SUB>2</SUB> mol<SUP>−1</SUP> xylose. This study showed that pretreatments differentially affect the structure and productivity of the active mesophilic and thermophilic microbial community developed from an inoculum.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Temperature and pH shock differentially affected dark fermentation of xylose. </LI> <LI> The effect of pretreatments on the community was studied using a RNA-based approach. </LI> <LI> Acidic or alkaline shocks led to the highest H<SUB>2</SUB> yield at 37 and 55 °C, respectively. </LI> <LI> At 37 °C, relative abundance of <I>Clostridiaceae</I> and H<SUB>2</SUB> yield correlated linearly. </LI> <LI> At 55 °C, lactate production was repressed only by an alkaline shock pretreatment. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>