Prefermentation improves xylose utilization in simultaneous saccharification and co-fermentation of pretreated spruce

<p>Abstract</p> <p>Background</p> <p>Simultaneous saccharification and fermentation (SSF) is a promising process option for ethanol production from lignocellulosic materials. However, both the overall ethanol yield and the final ethanol concentration in the fermentation...

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Main Authors: Olofsson Kim, Bertilsson Magnus, Lidén Gunnar
Format: Article
Language:English
Published: BMC 2009-04-01
Series:Biotechnology for Biofuels
Online Access:http://www.biotechnologyforbiofuels.com/content/2/1/8
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spelling doaj-afbd90804fa745caaf617c0cb057fa1e2020-11-24T21:15:34ZengBMCBiotechnology for Biofuels1754-68342009-04-0121810.1186/1754-6834-2-8Prefermentation improves xylose utilization in simultaneous saccharification and co-fermentation of pretreated spruceOlofsson KimBertilsson MagnusLidén Gunnar<p>Abstract</p> <p>Background</p> <p>Simultaneous saccharification and fermentation (SSF) is a promising process option for ethanol production from lignocellulosic materials. However, both the overall ethanol yield and the final ethanol concentration in the fermentation broth must be high. Hence, almost complete conversion of both hexoses and pentoses must be achieved in SSF at a high solid content. A principal difficulty is to obtain an efficient pentose uptake in the presence of high glucose and inhibitor concentrations. Initial glucose present in pretreated spruce decreases the xylose utilization by yeast, due to competitive inhibition of sugar transport. In the current work, prefermentation was studied as a possible means to overcome the problem of competitive inhibition. The free hexoses, initially present in the slurry, were in these experiments fermented before adding the enzymes, thereby lowering the glucose concentration.</p> <p>Results</p> <p>This work shows that a high degree of xylose conversion and high ethanol yields can be achieved in SSF of pretreated spruce with a xylose fermenting strain of <it>Saccharomyces cerevisiae </it>(TMB3400) at 7% and 10% water insoluble solids (WIS). Prefermentation and fed-batch operation, both separately and in combination, improved xylose utilization. Up to 77% xylose utilization and 85% of theoretical ethanol yield (based on total sugars), giving a final ethanol concentration of 45 g L<sup>-1</sup>, were obtained in fed-batch SSF at 10% WIS when prefermentation was applied.</p> <p>Conclusion</p> <p>Clearly, the mode of fermentation has a high impact on the xylose conversion by yeast in SSF. Prefermentation enhances xylose uptake most likely because of the reduced transport inhibition, in both batch and fed-batch operation. The process significance of this will be even greater for xylose-rich feedstocks.</p> http://www.biotechnologyforbiofuels.com/content/2/1/8
collection DOAJ
language English
format Article
sources DOAJ
author Olofsson Kim
Bertilsson Magnus
Lidén Gunnar
spellingShingle Olofsson Kim
Bertilsson Magnus
Lidén Gunnar
Prefermentation improves xylose utilization in simultaneous saccharification and co-fermentation of pretreated spruce
Biotechnology for Biofuels
author_facet Olofsson Kim
Bertilsson Magnus
Lidén Gunnar
author_sort Olofsson Kim
title Prefermentation improves xylose utilization in simultaneous saccharification and co-fermentation of pretreated spruce
title_short Prefermentation improves xylose utilization in simultaneous saccharification and co-fermentation of pretreated spruce
title_full Prefermentation improves xylose utilization in simultaneous saccharification and co-fermentation of pretreated spruce
title_fullStr Prefermentation improves xylose utilization in simultaneous saccharification and co-fermentation of pretreated spruce
title_full_unstemmed Prefermentation improves xylose utilization in simultaneous saccharification and co-fermentation of pretreated spruce
title_sort prefermentation improves xylose utilization in simultaneous saccharification and co-fermentation of pretreated spruce
publisher BMC
series Biotechnology for Biofuels
issn 1754-6834
publishDate 2009-04-01
description <p>Abstract</p> <p>Background</p> <p>Simultaneous saccharification and fermentation (SSF) is a promising process option for ethanol production from lignocellulosic materials. However, both the overall ethanol yield and the final ethanol concentration in the fermentation broth must be high. Hence, almost complete conversion of both hexoses and pentoses must be achieved in SSF at a high solid content. A principal difficulty is to obtain an efficient pentose uptake in the presence of high glucose and inhibitor concentrations. Initial glucose present in pretreated spruce decreases the xylose utilization by yeast, due to competitive inhibition of sugar transport. In the current work, prefermentation was studied as a possible means to overcome the problem of competitive inhibition. The free hexoses, initially present in the slurry, were in these experiments fermented before adding the enzymes, thereby lowering the glucose concentration.</p> <p>Results</p> <p>This work shows that a high degree of xylose conversion and high ethanol yields can be achieved in SSF of pretreated spruce with a xylose fermenting strain of <it>Saccharomyces cerevisiae </it>(TMB3400) at 7% and 10% water insoluble solids (WIS). Prefermentation and fed-batch operation, both separately and in combination, improved xylose utilization. Up to 77% xylose utilization and 85% of theoretical ethanol yield (based on total sugars), giving a final ethanol concentration of 45 g L<sup>-1</sup>, were obtained in fed-batch SSF at 10% WIS when prefermentation was applied.</p> <p>Conclusion</p> <p>Clearly, the mode of fermentation has a high impact on the xylose conversion by yeast in SSF. Prefermentation enhances xylose uptake most likely because of the reduced transport inhibition, in both batch and fed-batch operation. The process significance of this will be even greater for xylose-rich feedstocks.</p>
url http://www.biotechnologyforbiofuels.com/content/2/1/8
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AT bertilssonmagnus prefermentationimprovesxyloseutilizationinsimultaneoussaccharificationandcofermentationofpretreatedspruce
AT lidengunnar prefermentationimprovesxyloseutilizationinsimultaneoussaccharificationandcofermentationofpretreatedspruce
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