Ethanol fermentation by xylose-assimilating Saccharomyces cerevisiae using sugars in a rice straw liquid hydrolysate concentrated by nanofiltration
Sasaki, K.; Sasaki, D.; Sakihama, Y.; Teramura, H.; Yamada, R.; Hasunuma, T.; Ogino, C.; Kondo, A.
Bioresource Technology 147: 84-88
ISSN/ISBN: 1873-2976 PMID: 23994307 DOI: 10.1016/j.biortech.2013.07.091
Concentrating sugars using membrane separation, followed by ethanol fermentation by recombinant xylose-assimilating Saccharomyces cerevisiae, 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 2.0 MPa, 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 S. cerevisiae was double (5.34-6.44 g L(-1)) that compared with fermentation of liquid hydrolysate before membrane separation (2.75 g L(-1)).