GLBRC's Sustainability Research Area


Focusing on one attribute comes at a high price.

At the GLBRC, sustainability researchers are exploring complex issues in agricultural and industrial systems. Research focuses on understanding the attributes and mechanisms responsible for the environmental sustainability of biofuel production systems, such as environmental impacts — many of which may be positive — and socioeconomic factors including incentives and policy options

Learn about the Center's research approach

Sustainability Leadership

Scientific Director, Sustainability Lead

A crop and soil scientist and ecosystem ecologist, Robertson focuses much of his research on the role that agriculture plays in greenhouse gas dynamics, and he is internationally known for his expertise in this area. Robertson has been the director...

Sustainability Lead

Jackson’s program focuses on structure and function of managed, semi-natural and natural grassland ecosystems. Research in Jackson’s grassland ecology lab spans many levels of ecological organization, from grass identification at the DNA level to landscape diversity effects on alternative biofuels...

Project Overview

A device used for measuring plant utilization of solar radiation sits in front of plots of switchgrass, corn and poplar growing in the Great Lake Bioenergy Research Center's fields at the Arlington Agricultural Research Station in Arlington, WI.GLBRC Sustainability research ranges from the microbial community level to regional modeling, and researchers conduct fieldwork at different project sites to reflect this diversity of scale. Small plots at Kellogg Biological Station in Michigan and the Arlington Agricultural Research Station in Wisconsin provide locations for measurement-intensive experiments, while investigators work in larger scale-up fields to collect data on carbon balances and biogeochemical processes. Finally, researchers pursue ecosystem-level biodiversity questions across landscapes, including marginal lands, in central Michigan and Wisconsin.

Specific sustainability projects include:

  • Novel biofuel production systems
  • Microbial-plant interactions for improved biofuel production
  • Biogeochemical responses
  • Biodiversity responses
  • Economic responses
  • Modeling, design and testing of drop-in fuels
  • Process synthesis and technoeconomic evaluation for biomass-to-fuels technologies.


Sustainability Publications

Stress-induced neutral lipid biosynthesis in microalgae—Molecular, cellular and physiological insights

Krzysztof Zienkiewicz; Zhi-Yan Du; Wei Ma; Katharina Vollheyde; Christoph Benning

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Photosynthetic microalgae have promise as biofuel feedstock. Under certain conditions, they produce substantial amounts of neutral lipids, mainly in the form of triacylglycerols (TAGs), which can be converted to fuels. Much of our current knowledge on the genetic and molecular basis of algal neutral lipid metabolism derives mainly from studies of plants, i.e. seed tissues, and to a lesser extent from direct studies of algal lipid metabolism. Thus, the knowledge of TAG synthesis and the cellular trafficking of TAG precursors in algal cells is to a large extent based on genome predictions, and most aspects of TAG metabolism have yet to be experimentally verified. The biofuel prospects of microalgae have raised the interest in mechanistic studies of algal TAG biosynthesis in recent years and resulted in an increasing number of publications on lipid metabolism in microalgae. In this review we summarize the current findings on genetic, molecular and physiological studies of TAG accumulation in microalgae. Special emphasis is on the functional analysis of key genes involved in TAG synthesis, molecular mechanisms of regulation of TAG biosynthesis, as well as on possible mechanisms of lipid droplet formation in microalgal cells.

Switchgrass ash content response to harvest timing and two harvest/storage methods of a bioenergy cropping system in the Great Lakes Region

Andrew Adkins; Kurt Thelen

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Energy production from the cofiring of plant residue is optimized when ash content of the biomass is minimized. Combustion of bioenergy crop material to produce energy may provide a transition market as cellulosic bioethanol production systems are being developed. A study was conducted to quantify the ash content of switchgrass biomass at a whole-plant scale under four harvest timings and two general harvest/storage methods in the Northern Corn Belt/Great Lakes Region. Results showed that switchgrass ash content was significantly reduced when the biomass was left to overwinter in the field. Although overwintering maximized mineral nutrient retention in the field and produced the best quality biomass for cofiring, it was at the expense of harvest yield. Ash content was largely not significantly influenced by harvest timing during the fall. This suggested increased harvest timing flexibility that was not at the expense of soil nutrient retention. This would allow farmers a wider harvest window to maximize harvest yields. Results showed that harvest/storage method did not have a significant effect on ash content. This further suggested flexibility and adaptability to farmers and the bioethanol industry. This would give the flexibility to choose an appropriate storage method in the context of region-specific conditions without compromising on ash content and the potential for cofiring the biomass or lignocellulosic ethanol production byproducts.

The fungal cultivar of leaf-cutter ants produces specific enzymes in response to different plant substrates

Lily Khadempour; Kristin E. Burnum-Johnson; Erin S. Baker; Carrie D. Nicora; Bobbie-Jo M. Webb-Robertson; Richard A. White; Matthew E. Monroe; Eric L. Huang; Richard D. Smith; Cameron R. Currie

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Herbivores use symbiotic microbes to help derive energy and nutrients from plant material. Leaf-cutter ants are a paradigmatic example, cultivating their mutualistic fungus Leucoagaricus gongylophorus on plant biomass that workers forage from a diverse collection of plant species. Here, we investigate the metabolic flexibility of the ants’ fungal cultivar for utilizing different plant biomass. Using feeding experiments and a novel approach in metaproteomics, we examine the enzymatic response of L. gongylophorus to leaves, flowers, oats or a mixture of all three. Across all treatments, our analysis identified and quantified 1766 different fungal proteins, including 161 putative biomass-degrading enzymes. We found significant differences in the protein profiles in the fungus gardens of subcolonies fed different plant substrates. When provided with leaves or flowers, which contain the majority of their energy as recalcitrant plant polymers, the fungus gardens produced more proteins predicted to break down cellulose: endoglucanase, exoglucanase and β-glucosidase. Further, the complete metaproteomes for the leaves and flowers treatments were very similar, while the mixed substrate treatment closely resembled the treatment with oats alone. This indicates that when provided a mixture of plant substrates, fungus gardens preferentially break down the simpler, more digestible substrates. This flexible, substrate-specific enzymatic response of the fungal cultivar allows leaf-cutter ants to derive energy from a wide range of substrates, which likely contributes to their ability to be dominant generalist herbivores.

The plant secretory pathway for the trafficking of cell wall polysaccharides and glycoproteins

Sang-Jin Kim; Federica Brandizzi

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Plant endomembranes are required for the biosynthesis and secretion of complex cell wall matrix polysaccharides, glycoproteins and proteoglycans. To define the biochemical roadmap that guides the synthesis and deposition of these cell wall components it is first necessary to outline the localization of the biosynthetic and modifying enzymes involved, as well as the distribution of the intermediate and final constituents of the cell wall. Thus far, a comprehensive understanding of cell wall matrix components has been hampered by the multiplicity of trafficking routes in the secretory pathway, and the diverse biosynthetic roles of the endomembrane organelles, which may exhibit tissue and development specific features. However, the recent identification of protein complexes producing matrix polysaccharides, and those supporting the synthesis and distribution of a grass-specific hemicellulose are advancing our understanding of the functional contribution of the plant secretory pathway in cell wall biosynthesis. In this review, we provide an overview of the plant membrane trafficking routes and report on recent exciting accomplishments in the understanding of the mechanisms underlying secretion with focus on cell wall synthesis in plants.

Tricin-lignins: occurrence and quantitation of tricin in relation to phylogeny

Wu Lan; Jorge Rencoret; Fachuang Lu; Steven D. Karlen; Bronwen G. Smith; Philip J. Harris; José Carlos Del Rio; John Ralph

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Tricin (5,7-dihydroxy-2-(4-hydroxy-3,5-dimethoxyphenyl)-4H-chromen-4-one), a flavone, was recently established as an authentic monomer in grass lignification that likely functions as a nucleation site. It is linked onto lignin as an aryl alkyl ether by radical coupling with monolignols or their acylated analogs. However, the level of tricin that incorporates into lignin remains unclear. Herein, three lignin characterization methods, acidolysis, thioacidolysis, and Derivatization Followed by Reductive Cleavage (DFRC), were applied to quantitatively assess the amount of lignin-integrated tricin. Their efficiencies at cleaving the tricin-(4'-O-beta)-ether bonds and the degradation of tricin under the corresponding reaction conditions were evaluated. A hexadeuterated tricin analog was synthesized as an internal standard for accurate quantitation purposes. Thioacidolysis proved to be the most efficient method, liberating more than 91% of the tricin with little degradation. A survey of different seed-plant species for the occurrence and content of tricin showed that it is widely distributed in the lignin from species in the family Poaceae (order Poales). Tricin occurs at low levels in some commelinid monocotyledon families outside the Poaceae such as the Arecaceae (the palms, order Arecales) and Bromeliaceae (Poales), and the non-commelinid monocotyledon family Orchidaceae (Orchidales). One eudicotyledon was found to have tricin (Medicago sativa, Fabaceae). The content of lignin-integrated tricin is much higher than the extractable tricin level in all cases. Lignins, including waste lignin streams from biomass processing, could therefore provide a large and alternative source of this valuable flavone, reducing the costs, and encouraging studies into its application beyond its current roles. This article is protected by copyright. All rights reserved.