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Conversion of hemicelluloses and D-xylose into ethanol by the use of thermophilic anaerobic bacteria

Abstract

Ethanol is a CO{sub 2} neutral liquid fuel that can substitute the use of fossil fuels in the transportation sector, thereby reducing the CO{sub 2} emission to the atmosphere. CO{sub 2} emission is suspected to contribute significantly to the so-called greenhouse effect, the global heating. Substrates for production of ethanol must be cheap and plentiful. This can be met by the use of lignocellulosic biomass such as willow, wheat straw, hardwood and softwood. However, the complexity of these polymeric substrates and the presence of several types of carbohydrates (glucose, xylose, mannose, galactose, arabinose) require additional treatment to release the useful carbohydrates and ferment the major carbohydrates fractions. The costs related to the ethanol-production must be kept at a minimum to be price competitive compared to gasoline. Therefore all of the carbohydrates present in lignocellulose need to be converted into ethanol. Glucose can be fermented to ethanol by yeast strains such as Saccharomyces cerevisiae, which, however, is unable to ferment the other major carbohydrate fraction, D-xylose. Thermophilic anaerobic ethanol producing bacteria can be used for fermentation of the hemicelluloses fraction of lignocellulosic biomass. However, physiological studies of thermophilic anaerobic bacteria have shown that the ethanol yield decreases at increasing substrate concentration.  More>>
Authors:
"NONE"
Publication Date:
May 01, 1998
Product Type:
Technical Report
Report Number:
NEI-DK-3164
Reference Number:
SCA: 090900; PA: DK-98:001292; EDB-98:048220; NTS-98:005143; SN: 98001944134
Resource Relation:
Other Information: DN: EFP-94; PBD: [1998]
Subject:
09 BIOMASS FUELS; HEMICELLULOSE; ETHANOL; BIOMASS CONVERSION PLANTS; ANAEROBIC CONDITIONS; XYLOSE; BACTERIA; YIELDS
OSTI ID:
591515
Research Organizations:
Danmarks Tekniske Univ., Lyngby (Denmark). Inst. for Miljoeteknologi
Country of Origin:
Denmark
Language:
English
Other Identifying Numbers:
Other: ON: DE98750801; CNN: Contract ENS-1383/94-0009; TRN: DK9801292
Availability:
OSTI as DE98750801
Submitting Site:
DK
Size:
[71] p.
Announcement Date:

Citation Formats

Conversion of hemicelluloses and D-xylose into ethanol by the use of thermophilic anaerobic bacteria. Denmark: N. p., 1998. Web.
Conversion of hemicelluloses and D-xylose into ethanol by the use of thermophilic anaerobic bacteria. Denmark.
1998. "Conversion of hemicelluloses and D-xylose into ethanol by the use of thermophilic anaerobic bacteria." Denmark.
@misc{etde_591515,
title = {Conversion of hemicelluloses and D-xylose into ethanol by the use of thermophilic anaerobic bacteria}
abstractNote = {Ethanol is a CO{sub 2} neutral liquid fuel that can substitute the use of fossil fuels in the transportation sector, thereby reducing the CO{sub 2} emission to the atmosphere. CO{sub 2} emission is suspected to contribute significantly to the so-called greenhouse effect, the global heating. Substrates for production of ethanol must be cheap and plentiful. This can be met by the use of lignocellulosic biomass such as willow, wheat straw, hardwood and softwood. However, the complexity of these polymeric substrates and the presence of several types of carbohydrates (glucose, xylose, mannose, galactose, arabinose) require additional treatment to release the useful carbohydrates and ferment the major carbohydrates fractions. The costs related to the ethanol-production must be kept at a minimum to be price competitive compared to gasoline. Therefore all of the carbohydrates present in lignocellulose need to be converted into ethanol. Glucose can be fermented to ethanol by yeast strains such as Saccharomyces cerevisiae, which, however, is unable to ferment the other major carbohydrate fraction, D-xylose. Thermophilic anaerobic ethanol producing bacteria can be used for fermentation of the hemicelluloses fraction of lignocellulosic biomass. However, physiological studies of thermophilic anaerobic bacteria have shown that the ethanol yield decreases at increasing substrate concentration. The biochemical limitations causing this phenomenon are not known in detail. Physiological and biochemical studies of a newly characterized thermophilic anaerobic ethanol producing bacterium, Thermoanaerobacter mathranii, was performed. This study included extraction of intracellular metabolites and enzymes of the pentose phosphate pathway and glycolysis. These studies revealed several bottlenecks in the D-xylose metabolism. This knowledge makes way for physiological and genetic engineering of this strain to improve the ethanol yield and productivity at high concentration of D-xylose. (au)}
place = {Denmark}
year = {1998}
month = {May}
}