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Applied Biochemistry and Biotechnology

, Volume 114, Issue 1–3, pp 585–599 | Cite as

Cellulase retention and sugar removal by membrane ultrafiltration during lignocellulosic biomass hydrolysis

Session 3—Bioprocessing, Including Separations

Abstract

Technologies suitable for the separation and reuse of cellulase enzymes during the enzymatic saccharification of pretreated corn stover are investigated to examine the economic and technical viability of processes that promote cellulase reuse while removing inhibitory reaction products such as glucose and cellobiose. The simplest and most suitable separation is a filter with relatively large pores on the order of 20–25 mm that retains residual corn stover solids while passing reaction products such as glucose and cellobiose to form a sugar stream for a variety of end uses. Such a simple separation is effective because cellulase remains bound to the residual solids. Ultrafiltration using 50-kDa polyethersulfone membranes to recover cellulase enzymes in solution was shown not to enhance further the saccharification rate or overall conversion. Instead, it appears that the necessary cellulase enzymes, including β-glucosidase, are tightly bound to the substrate; when fresh corn stover is contacted with highly washed residual solids, without the addition of fresh enzymes, glucose is generated at a high rate. When filtration was applied multiple times, the concentration of inhibitory reaction products such as glucose and cellobiose was reduced from 70 to 10 g/L. However, an enhanced saccharification performance was not observed, most likely because the concentration of the inhibitory products remained too high. Further reduction in the product concentration was not investigated, because it would make the reaction unnecessarily complex and result in a product stream that is much too dilute to be useful. Finally, an economic analysis shows that reuse of cellulase can reduce glucose production costs, especially when the enzyme price is high. The most economic performance is shown to occur when the cellulase enzyme is reused and a small amount of fresh enzyme is added after each separation step to replace lost or deactivated enzyme.

Index Entries

Saccharification corn stover cellulase glucose ultrafiltration vacuum filtration 

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References

  1. 1.
    Wooley, R., Ruth, M., Sheehan, J., Ibsen, K., Majdeski, H., and Galvez, A. (1999) Lignocellulosic Biomass to Ethanol Process Design and Economics Utilizing Co-Current Dilute Acid Prehydrolysis and Enzymatic Hydrolysis Current and Futuristic Scenarios, NREL/TP-580-26157, National Renewable Energy Laboratory, Golden, COGoogle Scholar
  2. 2.
    Aden, A., Ruth, M., Ibsen, K., Jechura, J., Neeves, K., Sheehan, J., Wallace, B., Montague, L., Slayton, A., and Lukas, J. (2002), Lignocellulosic Biomass to Ethanol Process Design and Economics Utilizing Co-Current Dilute Acid Prehydrolysis and Enzymatic Hydrolysis for Corn Stover, NREL/TP-510-32438, National Renewable Energy Laboratory, Golden, CO.Google Scholar
  3. 3.
    Mores, W. D., Knutsen, J. S., and Davis, R. H. (2001), Appl. Biochem. Biotechnol. 91–93, 297–309.PubMedCrossRefGoogle Scholar
  4. 4.
    Knutsen, J. S. and Davis, R. H. (2002), Appl. Biochem. Biotechnol. 98, 1161–1172.PubMedCrossRefGoogle Scholar
  5. 5.
    Ghose, T. K. and Kostick, J. A. (1970), Biotechnol. Bioengr. 12, 921–946.CrossRefGoogle Scholar
  6. 6.
    Howell, J. A. and Stuck, J. D. (1975), Biotechnol. Bioengr. 17, 873–893.CrossRefGoogle Scholar
  7. 7.
    Berghem, L. E. R., Pettersson, L. G., and Axiöfredriksson U. B. (1975), Eur. J. Biochem. 53, 55–62.CrossRefGoogle Scholar
  8. 8.
    Henley, R. G., Yang, R. Y. K., and Greenfield, P. F. (1980), Enzyme Microb. Technol. 2, 206–208.CrossRefGoogle Scholar
  9. 9.
    Hägerdal, B., López-Leiva, M., and Mattiasson, B. (1980), Desalination 35, 365–373.CrossRefGoogle Scholar
  10. 10.
    Klei, H. E., Sundstrom, D. W., Coughlin, R. W., and Ziolkowski, K. (1981), Biotechnol. Bioeng. 23, 593–601.Google Scholar
  11. 11.
    Alfani, F., Albanesi, D., Cantarella, M., Scardi, V., and Vetromile, A. (1982), Biomass 2, 245–253.CrossRefGoogle Scholar
  12. 12.
    Alfani, F., Cantarella, M., and Scardi, V. (1983), J. Membr., Sci. 16, 407–416.CrossRefGoogle Scholar
  13. 13.
    Ohlson, I., Trägårdh, G., and Hahn-Hägerdal, B. (1984), Biotechnol. Bioeng. 26, 647–653.CrossRefGoogle Scholar
  14. 14.
    Kinoshita, S., Chua J. W., Kato, N., Yoshida, T., and Taguchi, H. (1986), Enzyme Microb. Technol. 8, 691–695.CrossRefGoogle Scholar
  15. 15.
    Tan, L. U. L., Yu, E. K. C., Campbell, N., and Saddler, J. N. (1986), Appl. Microbiol. Biotechnol. 25, 250–255.Google Scholar
  16. 16.
    Tanaka, M., Fukui, M., and Matsuno, R. (1988), Biotechnol. Bioeng. 32, 897–902.CrossRefGoogle Scholar
  17. 17.
    Ishihara, M., Uemura, S., Hayashi, N., and Shimizu, K. (1991), Biotechnol. Bioeng. 37, 948–954.CrossRefGoogle Scholar
  18. 18.
    Roseiro, J. C., Conceicao, A. C., and Amaralcollaco, M. T. (1993), Bioresour. Technol. 43, 155–160.CrossRefGoogle Scholar
  19. 19.
    Cheryan, M. and Escobar, J. (1993), Improving Ethanol Production by Membrane Technology The Continuous Saccharification Reactor, National Renewable Energy Laboratory, Golden, CO.Google Scholar
  20. 20.
    Lee, S. G. and Kim, H. S. (1993), Biotechnol. Bioeng. 42, 737–746.CrossRefGoogle Scholar
  21. 21.
    Singh, N. and Cheryan, M. (1998), Starch-Stärke 50, 16–23.CrossRefGoogle Scholar
  22. 22.
    Lu, Y. P., Yang, B., Gregg, D., Saddler, J. N., and Mansfield, S. D. (2002), Appl. Biochem. Biotechnol. 98, 641–654.PubMedCrossRefGoogle Scholar
  23. 23.
    Kadam, K. and Knutsen, J. (2001), Saccharification, Experiments #6–9: Characterization of Cellulase Adsorption onto Pretreated Corn Stover, National Renewable Energy Laboratory, Golden, CO.Google Scholar
  24. 24.
    McMillan, J. D., Dowe, N., Mohagheghi A., and Newman, M. (1999), Reducing the Cost of Saccharification and Fermentation by Decreasing the Cellulase Enzyme Loading Required for Cellulose Conversion, National Renewable Energy Laboratory, Golden, CO.Google Scholar

Copyright information

© Humana Press Inc. 2004

Authors and Affiliations

  1. 1.Department of Chemical and Biological EngineeringUniversity of ColoradoBoulder

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