Skip to main content
NCBI home page
Applied and Environmental Microbiology logoLink to Applied and Environmental Microbiology
. 1981 Jun;41(6):1337–1343. doi: 10.1128/aem.41.6.1337-1343.1981

Ethanol Production by Thermophilic Bacteria: Fermentation of Cellulosic Substrates by Cocultures of Clostridium thermocellum and Clostridium thermohydrosulfuricum

Thomas K Ng 1,†, Arie Ben-Bassat 1,‡, J G Zeikus 1
PMCID: PMC243920  PMID: 16345787

Abstract

The fermentation of various saccharides derived from cellulosic biomass to ethanol was examined in mono- and cocultures of Clostridium thermocellum strain LQRI and C. thermohydrosulfuricum strain 39E. C. thermohydrosulfuricum fermented glucose, cellobiose, and xylose, but not cellulose or xylan, and yielded ethanol/acetate ratios of >7.0. C. thermocellum fermented a variety of cellulosic substrates, glucose, and cellobiose, but not xylan or xylose, and yielded ethanol/acetate ratios of ∼1.0. At nonlimiting cellulosic substrate concentrations (∼1%), C. thermocellum cellulase hydrolysis products accumulated during monoculture fermentation of Solka Floc cellulose and included glucose, cellobiose, xylose, and xylobiose. A stable coculture that contained nearly equal numbers of C. thermocellum and C. thermohydrosulfuricum was established that fermented a variety of cellulosic substrates, and the ethanol yield observed was twofold higher than in C. thermocellum monoculture fermentations. The metabolic basis for the enhanced fermentation effectiveness of the coculture on Solka Floc cellulose included: the ability of C. thermocellum cellulase to hydrolyze α-cellulose and hemicellulose; the enhanced utilization of mono- and disaccharides by C. thermohydrosulfuricum; increased cellulose consumption; threefold increase in the ethanol production rate; and twofold decrease in the acetate production rate. The coculture actively fermented MN300 cellulose, Avicel, Solka Floc, SO2-treated wood, and steam-exploded wood. The highest ethanol yield obtained was 1.8 mol of ethanol per mol of anhydroglucose unit in MN300 cellulose.

Full text

PDF
1337

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Cysewski G. R., Wilke C. R. Utilization of cellulosic materials through enzyamtic hydrolysis. I. Fermentation of hydrolysate to ethanol and single-cell protein. Biotechnol Bioeng. 1976 Sep;18(9):1297–1313. doi: 10.1002/bit.260180908. [DOI] [PubMed] [Google Scholar]
  2. Hsu E. J., Ordal Z. J. Comparative metabolism of vegetative and sporulating cultures of Clostridium thermosaccharolyticum. J Bacteriol. 1970 May;102(2):369–376. doi: 10.1128/jb.102.2.369-376.1970. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Lamed R., Zeikus J. G. Ethanol production by thermophilic bacteria: relationship between fermentation product yields of and catabolic enzyme activities in Clostridium thermocellum and Thermoanaerobium brockii. J Bacteriol. 1980 Nov;144(2):569–578. doi: 10.1128/jb.144.2.569-578.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Lee B. H., Blackburn T. H. Cellulase production by a thermophilic clostridium species. Appl Microbiol. 1975 Sep;30(3):346–353. doi: 10.1128/am.30.3.346-353.1975. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Miller D. L. Ethanol fermentation and potential. Biotechnol Bioeng Symp. 1975;(5):345–352. [PubMed] [Google Scholar]
  6. Millett M. A., Baker A. J., Satter L. D. Pretreatments to enhance chemical, enzymatic, and microbiological attack of cellulosic materials. Biotechnol Bioeng Symp. 1975;(5):193–219. [PubMed] [Google Scholar]
  7. Nelson D. R., Zeikus J. G. Rapid method for the radioisotopic analysis of gaseous end products of anaerobic metabolism. Appl Microbiol. 1974 Aug;28(2):258–261. doi: 10.1128/am.28.2.258-261.1974. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Ng T. K., Weimer T. K., Zeikus J. G. Cellulolytic and physiological properties of Clostridium thermocellum. Arch Microbiol. 1977 Jul 26;114(1):1–7. doi: 10.1007/BF00429622. [DOI] [PubMed] [Google Scholar]
  9. Weimer P. J., Zeikus J. G. Fermentation of cellulose and cellobiose by Clostridium thermocellum in the absence of Methanobacterium thermoautotrophicum. Appl Environ Microbiol. 1977 Feb;33(2):289–297. doi: 10.1128/aem.33.2.289-297.1977. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Wiegel J., Ljungdahl L. G., Rawson J. R. Isolation from soil and properties of the extreme thermophile Clostridium thermohydrosulfuricum. J Bacteriol. 1979 Sep;139(3):800–810. doi: 10.1128/jb.139.3.800-810.1979. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Zeikus J. G., Ben-Bassat A., Hegge P. W. Microbiology of methanogenesis in thermal, volcanic environments. J Bacteriol. 1980 Jul;143(1):432–440. doi: 10.1128/jb.143.1.432-440.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Zeikus J. G. Chemical and fuel production by anaerobic bacteria. Annu Rev Microbiol. 1980;34:423–464. doi: 10.1146/annurev.mi.34.100180.002231. [DOI] [PubMed] [Google Scholar]

Articles from Applied and Environmental Microbiology are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES