Ethanol Fermentation from Hydrolyzed Hot-Water Wood Extracts with Candida shehatae and Pichia stipitis
Two strains of Candida shehatae and two Pichia stipitis strains were used to ferment Nano-membrane concentrated hot water wood extracts from sugar maple wood chips to ethanol. Of the four strains used the most promising strain appears to be the NRRL Y-11543 of P. stipitis. This strain was able to produce up to 14.5 g/L ethanol from wood extracts containing a mixture of 5-and 6-carbon sugars. While this mixture contains six different sugars it was composed primarily of xylose at 36.7 g/L with the other sugars ranging in concentration from 1.04 to 2.08 g/L. In addition to these sugars the concentrated wood extracts also contain many of the xylose oligomers and while P. stipitis has the ability to produce ethanol from xylan it more readily uses monosaccharide. Through dilute acid hydrolysis these oligomers can be convened to xylose. The sugar maple hydrolysate used in this study has a xylose concentration of 86.8 g/L. By hydrolyzing the xylan polymers, acetyl groups are released increasing the concentration of acetic acid in the solution, and furfurals are also formed as a result of the high temperatures and low pH. While Nano-membrane removed majority of the acetates, formats, furfurals, methanol, etc., the sulfate introduced through the hydrolysis process remained. High level of sulfate and aromatic compounds in the hydrolysate are inhibitory to the fermentation process. P. stipitis did not produce much ethanol from this hydrolysate without diluting it with distilled water. The highest ethanol concentration reached was 18.4 g/L by diluting the hydrolysate in a 1:1 ratio with distilled water.
Alan M. Shupe Shijie Liu
Department of Paper and Bioprocess Engineering SUNY ESF 1 Forestry Drive,Syracuse,NY 13210
国际会议
广州
英文
607-613
2008-12-03（万方平台首次上网日期，不代表论文的发表时间）