초록
<P><B>Abstract</B></P> <P>Concentrating sugars using membrane separation, followed by ethanol fermentation by recombinant xylose-assimilating <I>Saccharomyces cerevisiae</I>, is an attractive technology. Three nanofiltration membranes (NTR-729HF, NTR-7250, and ESNA3) were effective in concentrating glucose, fructose, and sucrose from dilute molasses solution and no permeation of sucrose. The separation factors of acetate, formate, furfural, and 5-hydroxymethyl furfural, which were produced by dilute acid pretreatment of rice straw, over glucose after passage through these three membranes were 3.37–11.22, 4.71–20.27, 4.32–16.45, and 4.05–16.84, respectively, at pH 5.0, an applied pressure of 1.5 or 2.0MPa, and 25°C. The separation factors of these fermentation inhibitors over xylose were infinite, as there was no permeation of xylose. Ethanol production from approximately two-times concentrated liquid hydrolysate using recombinant <I>S. cerevisiae</I> was double (5.34–6.44gL<SUP>–1</SUP>) that compared with fermentation of liquid hydrolysate before membrane separation (2.75gL<SUP>–1</SUP>).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Three membranes concentrated sugars in rice straw liquid hydrolysate. </LI> <LI> Sugars were selectively concentrated at pH 5.0. </LI> <LI> Ethanol was produced by xylose-assimilating yeast from concentrated sugars. </LI> </UL> </P>