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Title: Engineering cellulolytic bacterium Clostridium thermocellum to co-ferment cellulose- and hemicellulose-derived sugars simultaneously

Here, cellulose and hemicellulose are the most abundant components in plant biomass. A preferred Consolidated Bioprocessing (CBP) system is one which can directly convert both cellulose and hemicellulose into target products without adding the costly hydrolytic enzyme cocktail. In this work, the thermophilic, cellulolytic, and anaerobic bacterium, Clostridium thermocellum DSM 1313, was engineered to grow on xylose in addition to cellulose. Both xylA (encoding for xylose isomerase) and xylB (encoding for xylulokinase) genes from the thermophilic anaerobic bacterium Thermoanaerobacter ethanolicus were introduced to enable xylose utilization while still retaining its inherent ability to grow on 6-carbon substrates. Targeted integration of xylAB into C. thermocellum genome realized simultaneous fermentation of xylose with glucose, with cellobiose (glucose dimer), and with cellulose, respectively, without carbon catabolite repression. We also showed that the respective H 2 and ethanol production were twice as much when both xylose and cellulose were consumed simultaneously than when consuming cellulose alone. Moreover, the engineered xylose consumer can also utilize xylo-oligomers (with degree of polymerization of 2-7) in the presence of xylose. Isotopic tracer studies also revealed that the engineered xylose catabolism contributed to the production of ethanol from xylan which is a model hemicellulose in mixed sugar fermentation, demonstratingmore » immense potential of this enhanced CBP strain in co-utilizing both cellulose and hemicellulose for the production of fuels and chemicals.« less
 [1] ;  [2] ;  [1] ;  [1] ; ORCiD logo [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States); Univ. de los Andes, Bogota (Columbia)
Publication Date:
Report Number(s):
Journal ID: ISSN 0006-3592
Grant/Contract Number:
AC36-08GO28308; 0627-1403
Accepted Manuscript
Journal Name:
Biotechnology and Bioengineering
Additional Journal Information:
Journal Volume: 115; Journal Issue: 7; Journal ID: ISSN 0006-3592
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Hydrogen and Fuel Cell Technologies Program (EE-3F); USDOE Office of Energy Efficiency and Renewable Energy (EERE), NREL Laboratory Directed Research and Development (LDRD); USDOE
Country of Publication:
United States
09 BIOMASS FUELS; lignocellulose; Clostridium thermocellum; consolidated bioprocessing (CBP); xylose; biohydrogen; thermophile
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1432725