초록
<P><B>Abstract</B></P><P><B>BACKGROUND:</B> Simultaneous xylose isomerization and fermentation was investigated to improve the lactic acid production from xylose by <I>Lactobacillus pentosus</I> in a novel two‐in‐one bioreactor constructed by packing the immobilized xylose isomerase (65 g) in a fixed bed reactor (diameter 56 mm × 66 mm, packing volume 154 mL) with a permeable wall, which was installed inside a conventional fermenter (2 L) and rotated along the axis together with the mechanical stirrer of the fermenter.</P><P><B>RESULTS:</B> Xylose (20 g L<SUP>−1</SUP>) was completely consumed within 24 h in the novel bioreactor, compared with 72 h needed for the control without packed enzyme. The maximum cell density (17.5 g L<SUP>−1</SUP>) in the novel bioreactor was twice that in the control and the lactic acid productivity (0.58 g L<SUP>−1</SUP> h<SUP>−1</SUP>) was 3.8 times higher. Repeated use of the immobilized enzyme showed that the lactic acid productivity and yield obviously dropped after the first batch fermentation but maintained almost unchanged afterwards.</P><P><B>CONCLUSION:</B> Simultaneous xylose isomerization and fermentation significantly improved lactic acid production from xylose by <I>Lactobacillus pentosus</I>. The novel bioreactor made it easier to recycle and reuse the immobilized enzyme. © 2012 Society of Chemical Industry</P>