Biomass Depolymerization projects
NMR Analytical Tools for Biofuel Research
NMR spectroscopy is one of the most versatile methods available for chemical analysis, but also has excellent capabilities for studying dynamic processes, and even the spatial distribution of compounds. This work applies NMR spectroscopy to analysis of feedstock materials, materials after various deconstruction reactions, and model systems for biofuel production. New NMR experiments will provide desired information about chemical structures, dynamics, etc. Experiments are done in conjunction other groups in the EBI to provide samples from processes and chemistry being studied in the Institute.
In order to manipulate plant biomass recalcitrance, research needs to focus on understanding lignocellulose cell wall biosynthesis and structure as well as developing efficient deconstruction and conversion technologies. Continuing improvement of analytical techniques is also important to support or enable these key tasks. NMR is one of the most powerful analytical techniques available for the characterization of biomass. There are numerous methodologies adapted and designed for biofuels research to characterize the chemical and molecular structure of lignocellulosic biomass. We have continued application and development of NMR methods for analysis of samples of interest to EBI investigators.
We have continued to apply NMR spectroscopy to analysis of materials relevant for biofuel production from lignocellulosic biomass. Work has continued on analysis of lignin, including both distribution of monomer units in material from different sources, and on the linkages between monomers. Products from catalytic reactions designed to break linkages have been studied. We have initiated studies of 13C-labeled cell walls using both solution and solid state NMR. The results of the action of bacterial strains that can metabolize lignin have been examined using both natural and synthetic lignin. We have also examined soluble metabolites from yeast strains designed for growth on xylose.
Nuclear Magnetic Resonance (NMR) is being used to determine the chemical makeup of biofuel feedstock materials, such as cell walls from the grass Miscanthus. This approach is particularly valuable for analyzing heterogeneous, polymeric materials such as lignin that is a structural component of plant cell walls. We showed that by using an ionic liquid in organic solvent, we can analyze full plant cell walls, determining amounts of different lignin building blocks, how these are linked together in the lignin polymer, and the distribution of different sugars in the cell walls. Using just the lignin component, we showed that linkages between specific sugars and aromatic units on the lignin are the dominant chemical ties between the two types of cell wall polymers. Analyses of cell walls from plants in which specific laccase enzymes have been disabled showed that the distribution of lignin building blocks changes significantly. We have also analyzed products of catalytic reactions, developed by EBI investigators, that break up lignin and make the cellulose more accessible. The NMR data show that the reactive groups in intact lignin are the same as those that react in model compounds. Chemical products from other enzyme reactions involved in cell wall breakdown are being determined.
Wemmer’s lab identified and quantified the amounts of the subunits of lignin, and the linkages through a set of 13C NMR experiments. They compared the compositions of different lignin preparations (varying extraction / treatment conditions). Wenner’s group implemented a way to identify hydroxyls by chemical modification and 31P NMR, which provided information complementary to traditional chemical analysis methods. Researchers also began comparing whole cell wall samples with extracted lignins.
Published in 2014
The Arabidopsis COBRA Protein Facilitates Cellulose Crystallization at the Plasma Membrane, N. Sorek, H. Sorek, A. Kijac, H. J. Szemenyei, D. E. Wemmer, K. Hématy, S. Bauer, C. R. Somerville, Journal of Biological Chemistry, pii: jbc.M114.607192, Oct. 20, 2014.
Published in 2013
Solution-State 2D NMR Spectroscopy of Plant Cell Walls Enabled by a Dimethylsulfoxide-d6/1-Ethyl-3-methylimidazolium Acetate Solvent, Kun Cheng, Hagit Sorek, Herbert Zimmerman, David E. Wemmer, and Markus Pauley, Analytical Chemistry, 85(6): pp. 3213-3221, doi: 10.1021/ac303529v, March 4, 2013.
Published in 2012
Characterization of Miscanthus giganteus Lignin Isolated by Ethanol Organosolv Process Under Reflux Condition, Stefan Bauer, Hagit Sorek, Valerie Mitchell, Ana Ibanez, David E. Wemmer, Journal of Agriculture and Food Chemistry, 60(30), pp. 8203-8212, doi:10.1021/jf302409d, July 23, 2012.