|Van Zyl, Willem|
Submitted to: Biotechnology for Fuels and Chemicals Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2002
Publication Date: 5/17/2002
Citation: Lynd, L.R., Zhang, Y., Fan, Z., Desai, S., Tyurin, M., Lagrange, D., Gundllapalli, S., Otero, R.C., Van Zyl, W.H., Weimer, P.J. 2002. The microbial cellulose utilization paradigm: fundamentals and implications for consolidated bioprocessing [abstract]. Biotechnology for Fuels and Chemicals Symposium Proceedings. p. 11 Interpretive Summary:
Technical Abstract: Most studies of cellulose hydrolysis over the last half century have focused on hydrolysis as an enzymatic phenomenon. This approach anticipates processes featuring production of cellulase in a step separate from cellulose hydrolysis. An alternative approach considers cellulose hydrolysis as a microbial phenomenon and anticipates processes in a consolidated bioprocessing (CBP) configuration featuring cellulase production, cellulose hydrolysis and anaerobic fermentation in a single step. The microbial paradigm naturally leads to an emphasis on different fundamental issues, organisms, cellulase systems, and applied milestones, as compared to the enzymatic paradigm. The aerobic and CBP approaches differ with respect to: 1) bioenergetic benefit of growth on cellulose; 2) hydrolytic product (cellodextrins vs. glucose or cellobiose); 3) type of hydrolase enzymes employed; 4) correlation of growth rates on cellulose and temperature and on ATP yield per unit time; 5) cell-specific cellulose hydrolysis rates; 6) mechanism of inhibition at high cellulose concentration; and 7) effects of surface area on hydrolysis rate. The possibility of cell-cellulase synergy in which the presence of cells in a cellulose-enzyme-microbe complex enhances the effectiveness of cellulase will also be examined. Support for this concept will be: 1) studies with thermophilic bacteria that utilize components of cellulosic biomass at a high rate, including; manipulation of such bacteria to improve properties related to product formation; 2) production of heterologous saccharolytic enzymes in Saccharomyces cerevisiae. These results will be considered in the context of fundamental issues such as those outlined above, as well as applied objectives.