The objective of this study was to evaluate the ethanol production from sugars contained in the giant reed (Arundo donax L.) hemicellulosic hydrolysate using Scheffersomyces stipitis CBS6054, a native xylose fermenting yeast. Giant reed hemicellulose hydrolysate was obtained after dilute-oxalic acid pretreatment under the following condition: 150 °C, 25 min and 5.0 % (w/w) oxalic acid. The pH was increased to 5.0 with Ca(OH)2, adjusted with NaOH to 5.5, 6.0 or 6.5, filter sterilized, and then transferred to sterilized 125 ml Erlenmeyer flasks. Neutralization with Ca(OH)2 decreased xylose and glucose 22% and 8% respectively, while acetic acid decreased 27%. Increasing the initial pH from 5.0 to 5.5, 6.0 and 6.5, respectively, evidently improved the fermentability of the giant reed hemicelluloses hydrolysate; no fermentation was observed at pH 5.0 after 96 h, while 8.20 gl-1 of ethanol -1 -1 were obtained at pH 6.0 after 48 h, with a yield of 0.33 (ge/gs) and a productivity of 0.17 g lh. The results achieved in the present study show that giant reed hemicellulose hydrolysate using pH neutralization with Ca(OH)2 reduces the content of inhibitory compounds of the hydrolysate and thus can be fermented to ethanol by Scheffersomycesstipitis CBS6054. The optimum pH of acid hydrolysate fermentation for ethanol production was 6.0-6.5.
Giant Reed Hemicellulose Hydrolyzate Fermented by Scheffersomyces Stipitis CBS6054
COSENTINO, Salvatore;
2011-01-01
Abstract
The objective of this study was to evaluate the ethanol production from sugars contained in the giant reed (Arundo donax L.) hemicellulosic hydrolysate using Scheffersomyces stipitis CBS6054, a native xylose fermenting yeast. Giant reed hemicellulose hydrolysate was obtained after dilute-oxalic acid pretreatment under the following condition: 150 °C, 25 min and 5.0 % (w/w) oxalic acid. The pH was increased to 5.0 with Ca(OH)2, adjusted with NaOH to 5.5, 6.0 or 6.5, filter sterilized, and then transferred to sterilized 125 ml Erlenmeyer flasks. Neutralization with Ca(OH)2 decreased xylose and glucose 22% and 8% respectively, while acetic acid decreased 27%. Increasing the initial pH from 5.0 to 5.5, 6.0 and 6.5, respectively, evidently improved the fermentability of the giant reed hemicelluloses hydrolysate; no fermentation was observed at pH 5.0 after 96 h, while 8.20 gl-1 of ethanol -1 -1 were obtained at pH 6.0 after 48 h, with a yield of 0.33 (ge/gs) and a productivity of 0.17 g lh. The results achieved in the present study show that giant reed hemicellulose hydrolysate using pH neutralization with Ca(OH)2 reduces the content of inhibitory compounds of the hydrolysate and thus can be fermented to ethanol by Scheffersomycesstipitis CBS6054. The optimum pH of acid hydrolysate fermentation for ethanol production was 6.0-6.5.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
