초록
<P><B>Abstract</B></P> <P>Bioconversion of sugarcane bagasse (SCB) into hydrogen (H<SUB>2</SUB>) and organic acids was evaluated using a biomolecular approach to monitor the quantity and expression of the cellulase (<I>Cel</I>) gene. Batch reactors at 37 °C were operated with <I>Paraclostridium</I> sp. (10% v/v) and different substrates (5 g/L): glucose, cellulose and SCB <I>in natura</I> and pre-heat treated and hydrothermally. H<SUB>2</SUB> production from glucose was 162.4 mL via acetic acid (2.9 g/L) and 78.4 mL from cellulose via butyric acid (2.9 g/L). H<SUB>2</SUB> production was higher in hydrothermally pretreated SCB reactors (92.0 mL), heat treated (62.5 mL), when compared to <I>in natura</I> SCB (51.4 mL). Butyric acid (5.8, 4.9 and 4.0 g/L) was the main acid observed in hydrothermally, thermally pretreated, and <I>in natura</I> SCB, respectively. In the reactors with cellulose and reactors with hydrothermally pretreated SCB, the <I>Cel</I> gene copy number 3 and 2 log were higher, respectively, during the stage of maximum H<SUB>2</SUB> production rate, when compared to the initial stage. Differences in <I>Cel</I> gene expression were observed according to the concentration of soluble sugars in the reaction medium. That is, there was no gene expression at the initial phase of the experiment using SCB with 2.6 g/L of sugars and increase of 2.2 log in gene expression during the phases with soluble sugars of <1.4 g/L.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Paraclostridium</I> was identified as autochthonous bacteria from sugarcane bagasse. </LI> <LI> <I>Paraclostridium</I> produced H<SUB>2</SUB> from glucose, cellulose and sugarcane bagasse. </LI> <LI> The substrate type regulated the formation of the final product (acetic/butyric). </LI> <LI> There was cell growth during all stages of H<SUB>2</SUB> production. </LI> <LI> The cellulase family protein expression was regulated by soluble sugars. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>