초록
<P><B>Abstract</B></P> <P>Robust strains are essential towards success of <I>n</I>-butanol production from lignocellulosic feedstock. To find a suitable strain to convert a non-detoxified hemicellulosic hydrolysate of sugarcane bagasse, we first assessed the performance of four wild-type butanol-producing <I>Clostridium</I> strains (<I>C. acetobutylicum</I> DSM 6228, <I>C. beijerinckii</I> DSM 6422, <I>C. saccharobutylicum</I> DSM 13864, and <I>C. saccharoperbutylacetonicum</I> DSM 14923) in batch fermentations containing either xylose or glucose at 30 g L<SUP>−1</SUP> as sole carbon sources. <I>C. saccharoperbutylacetonicum</I> was selected after achieving butanol yields as high as 0.31 g g<SUP>−1</SUP> on glucose and 0.25 g g<SUP>−1</SUP> on xylose. In a 48-h fermentation containing a mixture of sugars (93% xylose and 7% glucose) that mimicked the hydrolysate, <I>C. saccharoperbutylacetonicum</I> delivered the highest butanol concentration (14.5 g L<SUP>−1</SUP>) when the initial sugar concentration was 50 g L<SUP>−1</SUP>. Moreover, the selected strain achieved the highest butanol yield (0.29 g g<SUP>−1</SUP>) on xylose-rich media reported so far. Meanwhile, <I>C. saccharoperbutylacetonicum</I> produced 5.8 g butanol L<SUP>−1</SUP> (0.22 g g<SUP>−1</SUP> butanol yield) when fermenting a non-detoxified sugarcane bagasse hemicellulosic hydrolysate enriched with xylose (30 g total sugars L<SUP>−1</SUP>). Although sugars were not exhausted (4.7 g residual sugars L<SUP>−1</SUP>) even after 72 h because of the presence of lignocellulose-derived microbial inhibitors, these results show that <I>C. saccharoperbutylacetonicum</I> is a robust wild-type strain. This microorganism with high butanol tolerance and yield on xylose can, therefore, serve as the basis for the development of improved biocatalysts for production of butanol from non-detoxified sugarcane bagasse hemicellulosic hydrolysate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Great ability of <I>C. saccharoperbutylacetonicum</I> to produce <I>n</I>-butanol from xylose. </LI> <LI> High-titer ABE production (>7.0 g/L) from non-detoxified hemicellulosic hydrolysate. </LI> <LI> Synergistic effect of inhibitors affected growth and ABE fermentation. </LI> <LI> Maximum <I>n</I>-butanol tolerance of <I>C. saccharoperbutylacetonicum</I> lies between 12 and 17 g/L </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>