Document Detail

Designing simultaneous saccharification and fermentation for improved xylose conversion by a recombinant strain of Saccharomyces cerevisiae.
MedLine Citation:
PMID:  18294716     Owner:  NLM     Status:  MEDLINE    
Wheat straw is an abundant agricultural residue which can be used as a raw material for bioethanol production. Due to the high xylan content in wheat straw, fermentation of both xylose and glucose is crucial to meet desired overall yields of ethanol. In the present work a recombinant xylose fermenting strain of Saccharomyces cerevisiae, TMB3400, cultivated aerobically on wheat straw hydrolysate, was used in simultaneous saccharification and fermentation (SSF) of steam pretreated wheat straw. The influence of fermentation strategy and temperature was studied in relation to xylose consumption, ethanol formation and by-product formation. In addition, model SSF experiments were made to further investigate the influence of temperature on xylose fermentation and by-product formation. In particular for SSF at the highest value of fibre content tested (9% water insoluble substance, WIS), it was found that a fed-batch strategy was clearly superior to the batch process in terms of ethanol yield, where the fed-batch gave 71% of the theoretical yield (based on all available sugars) in comparison to merely 59% for the batch. Higher ethanol yields, close to 80%, were obtained at a WIS-content of 7%. Xylose fermentation significantly contributed to the overall ethanol yields. The choice of temperature in the range 30-37 degrees C was found to be important, especially at higher contents of water insoluble solids (WIS). The optimum temperature was found to be 34 degrees C for the raw material and yeast strain studied. Model SSF experiments with defined medium showed strong temperature effects on the xylose uptake rate and xylitol yield.
Kim Olofsson; Andreas Rudolf; Gunnar Lidén
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-01-17
Journal Detail:
Title:  Journal of biotechnology     Volume:  134     ISSN:  0168-1656     ISO Abbreviation:  J. Biotechnol.     Publication Date:  2008 Mar 
Date Detail:
Created Date:  2008-03-03     Completed Date:  2008-07-21     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8411927     Medline TA:  J Biotechnol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  112-20     Citation Subset:  IM    
Department of Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden.
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MeSH Terms
Glucose / metabolism
Oxygen / metabolism
Promoter Regions, Genetic / genetics
Reverse Transcriptase Polymerase Chain Reaction
Saccharomyces cerevisiae / genetics,  metabolism*
Saccharomyces cerevisiae Proteins / genetics,  metabolism
Xylose / metabolism*
Reg. No./Substance:
0/Saccharomyces cerevisiae Proteins; 0/Xylose; 50-99-7/Glucose; 7782-44-7/Oxygen

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