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The Zhang Lab |
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Driving Tomorrow by Sugarsthrough Imagination, Invention and Innovation Select Honors 2008-2010 DuPont Young Professor Award Research Interests and Directions
Courses Taught BSE 5984 Enzyme Engineering (fall 2008, 2010) Research StatementOur research integrates chemical engineering design principles with protein biochemistry, microbiology, and modern biotechnology to solve several most important challenges for biofuels (transportation fuels, second generation cellulosic ethanol, butanol, and alkanes; third generation hydrogen and electricity) production from non-food renewable lignocellulose as below. Three main directions are: 1. Cellulose- and Organic-Solvent Lignocellulose Fractionation (COSLIF) Technology
In addition, we have developed Version 2 and 3 lignocellulose fractionation, which have solved two main shortcomings of Version 1 -- reducing solvent use volume by several fold and avoiding dilute sugar reconcentration.
2. Cellulase Engineering via Biomolecular Engineering The improvement of specific cellulase activities can be implemented through cellulase engineering -- rational design and directed evolution for each cellulase component as well as the reconstitution of cellulase components [2]. We are applying the combinatorial technologies involving DNA mutagenesis techniques, enzyme cell surface display techniques, and evolutionary engineering for improving cellulase activity on insoluble substrate cellulose. 3. Cellulose Hydrolysis Mechanisms Mediated by Cellulase, Cellulosome, and Cellulolytic Microbe Cellulose biodegradation requires three types of cellulases (endoglucanase, exoglucanases, and beta-glucosidase) to work together [3]. The unidentified characteristics of heterogeneous cellulose, the complicated interaction between solid cellulose and cellulase components, and the synergic/competitive relationship among various cellulase components limit our understanding of this de-polymerization process and also lags behind the developments in lignocellulose pretreatment and cellulase improvement. We have developed a generic functionally based mathematical model to simulate this complicated process [4]. A new rapid method has been developed to determine the degree of polymerization of cellulose [5]; a new kind of non-substitution, high reactivity, homogeneous, regenerated amorphous cellulose (RAC) has been prepared for studying cellulose hydrolysis [6]. Now we are developing several new technologies which will help us to characterize key substrate characteristics, and elucidate in-depth mechanisms that will provide new insights into lignocellulose pretreatment and cellulase improvement. In addition, we have discovered a new cellulose hydrolysis mechanism for microbial cellulose hydrolysis mediated by a complexed cellulase system -- the Clostridium thermocellum cellulosome [7,8]. 4. Enzymatic Hydrogen Production by Synthetic Enzymatic
Pathway[9]
What is more important, the integration of this technology with PEM fuel cell would achieve the highest energy efficiency from chemical energy to mechanical energy. The details of life cycle analysis pertaining to the carbohydrate hydrogen economy vs other hypocretical future economies, such as methanol economy, electron economy, are being conducted.
See Our Vision about the Future Transportation and Energy Storage .
References: [1] Zhang Y.-H.P., Ding S.-Y., Mielenz J.R., Cui J.-.B., Elander R.T., Laser M, Himmel M.E., McMillan, J.D., Lynd, L.R. 2007. Fractionating recalcitrant lignocellulose at modest reaction conditions. Biotechnology and Bioengineering 97(2): 214-223. [2] Zhang Y.-H.P., Himmel E. M., Mielenz J.R. 2006. Outlook for cellulase improvement: Screening and selection strategies. Biotechnology Advances, 22(5): 452-481. [3] Zhang Y.-H.P., and Lynd L.R. 2004. Toward an aggregated understanding of enzymatic hydrolysis of cellulose: non-complexed cellulase systems. Biotechnology and Bioengineering 88:797-824. [4] Zhang Y.-H.P., Lynd L.R. 2006. A functionally-based model for hydrolysis of solid cellulose by fungal cellulase. Biotechnology and Bioengineering, 94(5): 888-898. [5] Zhang Y.-H.P., and Lynd L.R. 2005. Determination of the number average degree of polymerization of cellodextrins and cellulose with application to enzymatic cellulose hydrolysis Biomacromolecules 6: 1510-1515. [6] Zhang Y.-H.P., Cui X.B., Lynd L.R., and Huang L. 2006. A transition from cellulose swelling to cellulose dissolution by o-phosphoric acid: Evidences from supramolecular structures and enzymatic hydrolysis. Biomacromolecules 7(2): 644-648. [7] Zhang Y.-H.P., and Lynd L.R. 2005. Cellulose utilization by Clostridium thermocellum: bioenergetics and hydrolysis product assimilation. Proceedings of the National Academy of Sciences of USA 102:7321-7325. [8] Lu Y.P., Zhang Y.-H.P., Lynd L.R. 2006. Evidence for enzyme-microbe synergy in cellulose utilization by Clostridium thermocellum. Proceedings of the National Academy of Sciences of USA 103(44): 16165-16169. [9] Zhang Y.-H.P., Mielenz J.R., Evans B.R., Hopkins R.C., Adams M.W.W. 2007. High-yield hydrogen production from starch and water by synthetic enzymatic pathway. PLOS ONE 2(5): e456. Select Collaborators:
If you are interested in our technology transfer (lignocellulose fractionation and enzymatic hydrogen production), please feel free to contact me or VTIP. Imagination, Innovation, Implementation (3I Biofuels Lab) |
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