Copyright © 2002, American Society for Microbiology
Microbial Cellulose Utilization: Fundamentals and Biotechnology
Lee R. Lynd,1* Paul J. Weimer,2 Willem H. van Zyl,3 and Isak S. Pretorius4
Chemical and Biochemical Engineering, Thayer School of Engineering and Department of Biological Sciences,Dartmouth College, Hanover, New Hampshire 03755,1 USDA Agricultural Research Service, U.S. Dairy Forage Research Center and Department of Bacteriology, Madison, Wisconsin, 53706,2 Department of Microbiology,3 Institute for Wine Biotechnology, University of Stellenbosch, Stellenbosch 7600, South Africa4
*Corresponding author. Mailing address: Chemical and Biochemical Engineering, Thayer School ofEngineering, Dartmouth College, Hanover, NY 03755. Phone: (603) 646-2231. Fax: (603) 646-2277. E-mail: email@example.com [pic].
[pic]This article has been corrected. See Microbiol Mol Biol Rev. 2002 December; 66(4): 739.
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Fundamental features of microbial cellulose utilization are examinedat successively higher levels of aggregation encompassing the structure and composition of cellulosic biomass, taxonomic diversity, cellulase enzyme systems, molecular biology of cellulase enzymes, physiology of cellulolytic microorganisms, ecological aspects of cellulase-degrading communities, and rate-limiting factors in nature. The methodological basis for studying microbial celluloseutilization is considered relative to quantification of cells and enzymes in the presence of solid substrates as well as apparatus and analysis for cellulose-grown continuous cultures. Quantitative description of cellulose hydrolysis is addressed with respect to adsorption of cellulase enzymes, rates of enzymatic hydrolysis, bioenergetics of microbial cellulose utilization, kinetics of microbial celluloseutilization, and contrasting features compared to soluble substrate kinetics. A biological perspective on processing cellulosic biomass is presented, including features of pretreated substrates and alternative process configurations. Organism development is considered for “consolidated bioprocessing” (CBP), in which the production of cellulolytic enzymes, hydrolysis of biomass, and fermentation ofresulting sugars to desired products occur in one step. Two organism development strategies for CBP are examined: (i) improve product yield and tolerance in microorganisms able to utilize cellulose, or (ii) express a heterologous system for cellulose hydrolysis and utilization in microorganisms that exhibit high product yield and tolerance. A concluding discussion identifies unresolved issuespertaining to microbial cellulose utilization, suggests approaches by which such issues might be resolved, and contrasts a microbially oriented cellulose hydrolysis paradigm to the more conventional enzymatically oriented paradigm in both fundamental and applied contexts.
Appl Microbiol. 1970 September; 20(3): 362–368.
Degradation and Utilization of Hemicellulose from IntactForages by Pure Cultures of Rumen Bacteria 1
Judith A. Coen and B. A. Dehority
Department of Animal Science, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691
1 Approved for publication as Journal Article no. 36-70 by the Ohio Agricultural Research and Development Center, Wooster, Ohio.
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Several pure strains of rumenbacteria have previously been shown to degrade isolated hemicelluloses from a form insoluble in 80% acidified ethanol to a soluble form, regardless of the eventual ability of the organism to utilize the end products as energy sources. This study was undertaken to determine whether similar hemicellulose degradation or utilization, or both, occurs from intact forages. Fermentations by pure cultures...