genomic.science@science.doe.gov
Office of Biological and Environmental Research
U.S. Department of Energy Office of Science
Susan Gregurick
Office of Biological and Environmental Research
U.S. Department of Energy Office of Science
genomic.science@science.doe.gov
Office of Biological and Environmental Research
U.S. Department of Energy Office of Science
Office of Biological and Environmental Research
U.S. Department of Energy Office of Science
"We are proud of the pieces of
the scientific puzzle we have
assembled. The Great Lakes
Bioenergy Research Center has
brought together 400 handpicked
scientists and staff and
established core facilities for
analyzing bioenergy microbes
and plants in the lab or the field.
The productivity of this team
has resulted in more than 100
peer-reviewed publications and
patentable technologies that can
serve as a foundation for a new
renewable bioenergy future."
– Tim Donohue
Tim Donohue is the GLBRC principal investigator and director as well as a professor of bacteriology at the University of Wisconsin–Madison. He is an expert in applying the latest genomic and systems biology approaches to understanding how genetic pathways and networks in microorganisms are used to generate cell biomass or biofuels from sunlight.
Project Description:
The DOE Great Lakes Bioenergy Research Center (GLBRC) is led by the University of Wisconsin– Madison, in close partnership with Michigan State University (see GLBRC Partners). Located in the world's most productive agricultural region, the GLBRC is exploring scientifically diverse approaches to converting sunlight and various plant feedstocks—agricultural residues, wood chips, and grasses—into biofuels. In addition to its broad range of research projects, the GLBRC is collaborating with agricultural researchers and producers to help develop the most economically viable and environmentally sustainable practices for bioenergy production. A new facility is being designed to house GLBRC and other UW–Madison bioenergy programs.
The GLBRC scientific portfolio is organized into four core discovery programs: (1) Improved Plants, (2) Improved Processing, (3) Improved Catalysts, and (4) Sustainable Biofuels Practices. Each core discovery program has a targeted set of mutually supportive goals designed to develop biofuel technologies and transfer them to industry. The GLBRC's sustainability projects span both basic science and applications. The center's research activities are integrated so that data and models generated in one area inform research and technology development by the other core discovery programs. Research support activities that cut across all four discovery areas include the development of enabling technologies such as automated screens for genes and proteins in plants and microbes (see figure, Automated Microbial Colony Picker at GLBRC, p. 21), the creation and management of informatics and information technology tools, and education and outreach. Some recent highlights and successes of GLBRC research are featured.
Research Strategy:
1. Improved Plants
In addition to investigating how genes affect cell-wall digestibility
in model plants, cornstalks, and switchgrass, GLBRC
researchers are using information from model and agronomic
systems to breed plants that produce more or altered hemicelluloses,
starches, oils, or new forms of lignin that are easier
to process into fuels. Plant oils have twice the energy content
of carbohydrates and require little energy to extract and
convert into biodiesel. GLBRC researchers aim to increase
the energy density of grasses and other nontraditional oil crops by understanding and manipulating the metabolic and
genetic circuits that control accumulation of oils and other
easily digestible, energy-rich compounds in plant tissues.
Automated Microbial Colony Picker at GLBRC. GLBRC screening efforts begin with the automated selection of microbial colonies in multiwell plates—selecting up to 7,000 colonies per hour. The robot then dispenses growth medium into the destination plates and seals the plates for analysis. [Photo by Wolfgang Hoffmann, University of Wisconsin–Madison]
2. Improved Processing
Located at the intersection of America's agricultural
heartland and its abundant northern forest biomass, the
GLBRC has access to a rich diversity of raw biomass
for study. GLBRC biomass-processing research focuses
on finding and improving natural cellulose-degrading
enzymes extracted from diverse environments. Improved
enzymes created by the GLBRC protein-production
pipeline are tested with a range of plant materials and
pretreatment conditions to identify the best combination
of enzymes, chemicals, and physical processing for enhancing
the digestibility of specific biomass sources. GLBRC
researchers identify and quantify small molecules generated
by different pretreatment methods and examine how
these molecules impact biofuel yield.
To decrease the costs of producing and using enzymes to break down cellulose in plants, scientists in this discovery program are working with plant-biomass researchers. They are expressing biomass-degrading enzymes in the stems and leaves of corn and other plants—essentially designing plants to "self-destruct" on cue in a biofuel production facility.
3. Improving Catalysts
GLBRC biomass-conversion research is driven by the need
to increase the quantity, diversity, and efficiency of energy
products derived from plant biomass. Cellulosic
ethanol
is a major focus for GLBRC research, but the center also
aims to improve both biological and chemical methods
for converting plant material into intermediate chemicals
that can be used to produce ethanol and other transportation
fuels. In addition to producing new generations
of cellulose-derived liquid transportation fuels, GLBRC
researchers are improving the processes by which microbes
directly convert a combination of biomass and sunlight
into hydrogen or electricity. Another target is to develop a
microbe capable of carrying out all biologically mediated
biofuel production steps. The GLBRC strategy to reach this
target is to start with efficient ethanol-producing microbes
and enable them to produce enzymes and pathways for
breaking down cellulose.
GLBRC Research on Bioenergy Crop Sustainability. To improve the sustainability of crops and agricultural residues used for energy production, GLBRC researchers are studying the symbiotic associations of crop roots with arbuscular mycorrhizal (AM) fungi. Interactions with AM fungi benefit host plants by improving the uptake of nutrients, especially phosphorus, nitrogen, and potassium from the soil. Establishing these symbiotic associations in crops grown under suboptimal conditions has the potential to increase biomass production while limiting use of fertilizers and pesticides. [Photo courtesy of the Great Lakes Bioenergy Research Center]
4. Sustainable
Bioenergy Practices
For the emerging cellulosic biofuel industry to have a positive
impact on the United States, complex issues involving
agricultural, industrial, and ecological systems as well as
factors affecting human decision making and behaviors
must be addressed. To create a better understanding of the larger context that ultimately influences the direction and
acceptance of new biotechnologies, GLBRC scientists are
examining the environmental and socioeconomic dimensions
of converting biomass to biofuel.
To determine the best practices for biofuel production, GLBRC researchers are analyzing the impacts of issues such as minimizing energy and chemical inputs for bioenergy crop production and reducing greenhouse gas emissions from the entire biofuel production life cycle (see figure, GLBRC Research on Bioenergy Crop Sustainability, this page). They also are seeking to understand the environmental impacts of removing leftover stalks, stems, and leaves from food crops. Data from these and other studies will allow GLBRC scientists to make predictions on the social and financial incentives needed to promote the adoption of more environmentally beneficial practices.
Education and Outreach
The staff and partners of the GLBRC Education and Outreach
area inform a variety of audiences about biofuels research,
energy concerns, and sustainability issues affecting our planet.
Their goal is to broaden the understanding of current issues
in bioenergy for the general public as well as for students and
educators at the K–12, undergraduate, and graduate levels. A
GLBRC
strong emphasis is placed on using critical thinking, quantitative
reasoning, and systems-based logic in the development of
bioenergy-related K–12 classroom materials and other informational
resources. Because bioenergy research and development
are important contemporary issues, Education and Outreach
members participate in various programs and events to present
research from GLBRC laboratories in a way that is accessible
and interesting to a broad array of audiences. Summer research
experiences for undergraduates at UW–Madison and Michigan
State University and other Education and Outreach projects are
described in detail at glbrc.org/education/.
Industry Partnerships
The GLBRC employs a systems-driven, genome-informed,
basic science approach within a project-management environment.
Thus, the center operates primarily in the early research
and development arena. The GLBRC is positioned to make key
discoveries and major advances that will lead to breakthrough
technologies for eventual large-scale conversion of biomass
into biofuels. Once a technology is developed, the center works
closely with industry partners through technology-transfer
mechanisms or collaboratively to achieve commercial implementation.
More information about collaborating with the
GLBRC is available at www.glbrc.org/industry/.
Lead Institution: University of Wisconsin–Madison
Principal Investigator: Timothy J. Donohue
GLBRC Partners:
Location of Center: University of Wisconsin-Madison
Alterations in Poplar Lignin Could Enhance
Pretreatment Efficiency
Alterations in lignin content or structure in plant cell walls can
have a profound effect on chemical or enzymatic degradability
and the efficiency by which certain pretreatment methods
remove lignin from polysaccharides. GLBRC researchers
found that overexpression of a particular gene [ferulate
5-hydroxylase (F5H)] in the lignin biosynthetic pathway of
a hybrid poplar created lignin with a structure and composition
that can enhance lignin removal from cellulose, while still
maintaining normal growth and development. When compared
to wild-type poplar, the up-regulated F5H poplar has a
much simpler lignin structure that is less branched and more
homogeneous in its subunit composition, which makes the
lignin easier to separate from cellulose during pretreatment.
This and other poplar transgenic materials under investigation
by GLBRC researchers have cell walls that release more sugar
than wild-type poplar over a range of pretreatment methods.
Ongoing work is examining the effect of ammonia fiber
expansion pretreatment on these transgenic poplars. Details
on the lignin structure of F5H up-regulated poplar were
reported in Stewart, J. J., et al. 2009. "The Effects on Lignin
Structure of Overexpression of Ferulate 5-Hydroxylase in
Hybrid Poplar," Plant Physiology 150(2), 621–35.
Integrated Biorefinery Concept. This figure shows the integrated system components analyzed by the Biorefinery and Farm Integration Tool. [Image from Sendich and Dale 2009]
New Modeling Tool Combines Environmental
and Economic Analysis of the Biorefinery
in Agricultural Landscapes
GLBRC researchers have provided a direct simulation of
different biorefinery configurations in realistic agricultural
landscapes for diverse locations throughout the United
States. Since no full-scale commercial examples of a cellulosic
biorefinery yet exist, forecasting the risks and tradeoffs of
the complete biofuel production chain requires the use of
modeling tools. Developed at GLBRC, the Biorefinery and
Farm Integration Tool (BFIT) enables a combined modeling
approach, including both crop and animal production, for
analyzing potential economic profitability as well as environmental
impacts (see figure). Focusing on ethanol production
from the two largest anticipated sources of cellulosic
biomass—corn stover and switchgrass—BFIT simulated the
farm-biorefinery interactions for nine different agricultural
regions using county-specific data for soil, weather, and farm
practice patterns. In all cases, cellulosic biofuel production
was integrated into existing farmlands. Results from the simulated
scenarios include projections for land area requirements,
annual farm income, nitrogen loss, greenhouse gas emissions,
total project investment, and minimum ethanol selling price.
Based on these projections, GLBRC researchers show that
introducing the cellulosic biorefinery and associated markets
could improve farm economics and reduce emissions without
additional clearing of lands for biofuels. BFIT research results
are reported in Sendich, E. D., and B. E. Dale. 2009. "Environmental
and Economic Analysis of the Fully Integrated
Biorefinery," GCB Bioenergy 1, 331–45.
Study Provides Insights on Maximizing
Energy-Rich Lipid Content in Leaves
Energy-rich lipids—with two times more energy than carbohydrates
or proteins—are life's primary molecules for energy
storage. Preventing the breakdown of lipids as leaves age
during the process of senescence is estimated to increase the
energy content of leaves by about 20%. GLBRC researchers
systematically studied the age-dependent changes in the
fatty acids of Arabidopsis, Brachypodium distachyon (a model
grass), and switchgrass leaves during natural plant senescence.
Researchers found that surface lipids were more stable
during senescence than membrane lipids, thus a potential
strategy for increasing the energy content of biofuel crops
might be to enhance surface lipid production. This research
was reported in Yang, Z., and J. B. Ohlrogge. 2009. "Turnover
of Fatty Acids During Natural Senescence of Arabidopsis,
Brachypodium, and Switchgrass and in Arabidopsis
β-Oxidation Mutants," Plant Physiology 150, 1981–89.
Sequencing Characterizes Bacterial Rhizosphere
Communities of Biofuel Crops on Marginal Lands
Using a new high-capacity sequencing technology, GLBRC
researchers characterized the structure of bacterial communities
living in the rhizosphere (microscopic zone surrounding
roots) of corn, soybean, canola, sunflower, and switchgrass.
Samples were taken from agricultural sites and adjacent native
forest in four locations with different soil types in Michigan.
Three of the locations were marginal lands unsuitable
for conventional agriculture, and a fourth site served as an
experimental control to evaluate crop yield and quality on
nonmarginal land. Although bacterial communities from biofuel
crops and forest were clearly differentiated, the communities
grouped mainly by location rather than by crop species,
and soil environment and land management were key factors
influencing community structure. Although more limited in
plant diversity, greater bacterial diversity was observed in the
biofuel crop samples than in the forest samples. Species of
Acidobacteria were the most abundant community members
in the rhizospheres of all plants, yet no strains have been
isolated for cultivation and characterization in the laboratory.
This research was reported in Jesus, E. C., et al. 2010. "Bacterial
Communities in the Rhizosphere of Biofuel Crops Grown
on Marginal Lands as Evaluated by 16S rRNA Gene Pyrosequences,"
Bioenergy Research 3, 20–27.
Chemical Hydrolysis of Cellulose Achieves High Glucose Yields. Applying this new chemical approach to the hydrolysis of pure cellulose results in glucose yields approaching 90% in just a few hours. Yields of unwanted by-products such as HMF (5-hydroxymethylfurfural, an inhibitor of microbial fermentation) and cellobiose (a molecule consisting of two linked glucose subunits) were minimal. [Image from Binder and Raines 2010]
Chemical Process Produces Simple, Fermentable
Sugars from Raw Biomass
A GLBRC research team has developed a promising new
chemical method to liberate the sugar molecules trapped
inside inedible plant biomass, a key step in the creation of
cellulosic biofuels. The new chemical process combines
ionic liquids and dilute acid to degrade cellulosic biomass
without the use of cellulases. In this approach, ionic liquids
make cell-wall polysaccharides accessible to chemical reactions
by decrystallizing
lignocellulosic biomass and dissolving
cellulose. Then, dilute hydrochloric acid at 105°C is used
to hydrolyze cellulose and hemicellulose into individual
sugar subunits. Applying this process to pure cellulose
resulted in nearly 90% yield of glucose (see figure), and
applying it to raw corn stover achieved sugar yields of 70% to
80%. By adding the right balance of water to the mixture, the
researchers reduced the formation of unwanted by-products
and demonstrated significant improvement in fermentable
sugar yields from ionic liquid treatment of lignocellulose
with yields comparable to those of enzymatic hydrolysis. Ionexclusion
chromatography was used to separate sugars from
the reaction mixture and recover the ionic liquids for reuse.
Sugars recovered from the hydrolyzed stover were readily
converted to ethanol by Escherichia coli and the yeast Pichia
stipitis. This research was reported in Binder, J. B., and R. T.
Raines. 2010. "Fermentable Sugars by Chemical Hydrolysis
of Biomass," Proceedings of the National Academy of Sciences
107, 4516–21.
