초록
<P><B>Abstract</B></P> <P>Solventogenic <I>Clostridium</I> strains usually do not ferment lignocellulosic biomass directly due to insufficient expression of hydrolyzing enzymes. In this study, we show that a solventogenic <I>Clostridium</I> strain BOH3 is able to produce both butanol and hydrogen when it ferments mixtures of agricultural residues and oil cakes. In particular, fermentation of mixed rice bran and sesame oil cake gives the highest butanol and hydrogen concentrations. In an optimized agro-residual medium (OAM) containing 94.5 g/l of rice bran and 36.7 g/l of sesame oil cake, BOH3 produces 13.50 ± 0.12 g/l of butanol and 4.41 ± 0.04 l/l of hydrogen after 7 days. Because BOH3 excretes hydrolyzing enzymes such as cellulase (0.52 ± 0.08 U/ml), xylanase (4.10 ± 0.05 U/ml) and amylase (2.05 ± 0.12 U/ml) during fermentation, BOH3 is able to perform fermentation and saccharification simultaneously when rice bran and sesame oil cakes are used as substrates. This is the first report showing that direct fermentation of agricultural residues by using solventogenic <I>Clostridia</I> is possible.</P> <P><B>Highlights</B></P> <P> <UL> <LI> BOH3 is a butanol-producing <I>Clostridium</I> strain expressing saccharolytic enzymes. </LI> <LI> BOH3 is able to perform saccharification and fermentation simultaneously. </LI> <LI> Optimized medium containing 94.5 g/l of rice bran and 36.7 g/l of sesame oil cake. </LI> <LI> BOH3 produces butanol (13.5 g/l) and hydrogen (4.41 l/l) in the optimized medium. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Several agro-residues are used as fermentation substrates or co-substrates for <I>Clostridium</I> strain BOH3 to produce butanol and hydrogen. Rice bran (RB) and sesame oil cake (SOC) are found to be the best substates. Optimized agro-residual medium (OAM) with RB (94.5 g/l) and SOC (36.7 g/l) enhances saccharolytic activity of BOH3 and production of butanol (>4 fold) and hydrogen (>2 fold).</P> <P>[DISPLAY OMISSION]</P>