Biomass Formation and Modification
Biomass Deconstruction and Conversion
Natural Biocatalysts Outperform Industry Standard
Comparative study finds heat-loving microbes could reduce the need for thermochemical pretreatment
In the most comprehensive controlled comparison to date of lignocellulosic solubilization by various biocatalysts, BESC researchers found that naturally cellulolytic microbes such as Clostridium thermocellum (stained green and growing on poplar tissue in image) achieved significantly higher solubilization yields over commercial pretreatment systems. [Image courtesy ORNL]Read More
Promise of Unusual Lignin Polymer as Feedstock for Carbon Fiber
Stronger, Lighter Carbon Fiber Could Be Used in Parts for Cars, Aircraft, Electronics, and Sports Equipment
BESC researchers discovered an unusual lignin polymer in the seed coats of vanilla beans (pictured) that is naturally biosynthesized from caffeyl (C) alcohol. In contrast to lignin polymers that are highly cross-linked, C-lignin is a linear polymer, which makes it easier to process into high-quality carbon fibers. [Image courtesy iStock]Read More
Identification of Poplar Adaptation Mechanisms
Findings Could Lead to More Efficient Ways of Breeding High-Ethanol-Yielding Poplar and Other Tree Species
Using whole-genome sequencing and high-throughput phenotyping, BESC researchers were able to rapidly pinpoint gene mutations responsible for causing low lignin levels in poplar trees planted in a variety of environmental conditions. This proof-of-concept will allow researchers to tag genes associated with other economically important but complex plant traits. [Image courtesy BESC]Read More
Beneficial Plant Gene Discovery
Research Lays Groundwork for New Ways of Manipulating Plants
BESC researchers discovered a previously uncharacterized gene (GXMT1), which directs a key step in the development of xylan, a principal component of cell walls in plants such as Arabidopsis (pictured). Characterizing this gene, which makes the plant resistant to biofuel conversion, will lead to improved strategies for modifying such cell wall structures to help turn plants into biofuel more efficiently. [Image courtesy iStock]Read More
Molecular Structure of Plant Biomass
Imaging Reveals Enzymes in Action and Significance of Plants' Nanoscale Architecture
Plant cell walls contain networks of cellulose microfibrils that can be broken down into sugars for fuel and complex polymers that shield the cellulose from enzymatic attack. To characterize cell wall structure at the subnanometer scale and assess its response to chemical pretreatment, BESC developed techniques to image enzyme digestion in real time, revealing that biomass reactivity is determined by the nanoscale architecture of plant cell walls.Read More
A Leap Forward in Microbial Ethanol Yields
Engineered yeast converts up to 97% of plant sugars into fuel
Scientists at BESC and research partner Mascoma LLC have developed an advanced strain of Saccharomyces cerevisiae that sets a new standard for conversion of biomass sugars from pretreated corn stover. While conventional yeast (pictured) leaves more than one-third of plant sugars unused in the form of xylose, the C5 FUEL™ microbe efficiently converts this xylose into ethanol in less than 48 hours.Read More
Real-World Performance of Low-Lignin Switchgrass
Field study assesses sugar release and ethanol yield in transgenic feedstock
Lignin in the cell walls of switchgrass and other bioenergy feedstocks severely limits the accessibility of cell wall carbohydrates to enzymatic breakdown into fermentable sugars and subsequently biofuels. In the first reported study of its kind, the biofuel potential of transgenic switchgrass with reduced lignin content was evaluated over two growing seasons.Read More
Using a "commercialization council" of technology transfer and intellectual property (IP) management professionals from partner institutions, BESC evaluates the commercial potential of new inventions arising from BESC research and promotes and facilitates the licensing of BESC IP.
BESC's education program, which is 75% self-sustaining, takes a novel approach. BESC has developed lesson plans to educate students about energy production and utilization. BESC uses a hub-and-spoke approach of working through regional science centers to maximize hands-on access and adaptation to local conditions.
Progress to Date
Creative Discovery Museum receives the Center for Interactive Learning and Collaboration Pinnacle Award
Mark Davis to Lead Biosciences Center at NREL
August 10, 2016
Microbial Upgrading of Lignin-Derived Carboxylates to Branched-Chain Esters for Drop-in Biofuels
An innovative biological conversion route was developed for conversion of lignocellulosic biomass or organic wastes into biofuels and high-value chemicals.
August 08, 2016
HPC Simulation of Co-Solvent Pretreatment of Biomass Confirmed by Experiment
Previous BESC work has shown that reaction of biomass in aqueous tetrahydrofuran (THF) in CELF (Co-solvent Enhanced Lignocellulosic Fractionation) pretreatment is highly effective at delignification and deconstruction of biomass for biofuels and bioproducts. Molecular dynamics simulations were performed of whole cellulose fibers and single cellulose chains in a THF-water co-solvent at various temperatures on the ORNL TITAN supercomputer. The simulations were complemented by THF-water experiments on cellulose, measuring its solubilization and imaging the product residue.
July 27, 2016
One-hour hydrolysis rate versus cumulative cellulose conversion for uninterrupted and restarted hydr (...more)
Cellulose DP And Accessibility Contribute To Cellulase Enzyme Action On Biomass Substrate
The enzymatic hydrolysis of lignocellulosic biomass proceeds initially at a fast rate followed by a rapid decrease in the conversion rates. Degree of polymerization (DP) analysis during hydrolysis suggested a synergistic action of endo- and exo-glucanases that contribute to the occurrence of a peeling off mechanism. Cellulose accessibility analysis showed that limited accessible surface area of cellulose is probably not a major limiting factor that causes the decline of hydrolysis rate in its late stage. Restart hydrolysis experiment suggested that enzyme related factors such as enzyme inactivation or steric hindrance of enzymes should be responsible to the reduction in hydrolysis rate given the large size of cellulase enzymes.
June 21, 2016
James Liao Appointed To Serve As Academia Sinica President
Dr. James Liao has been named as the 11th president of Academia Sinica — the top academic research institution in Taiwan. Academia Sinica supports research activities in a wide variety of disciplines, ranging from mathematical and physical sciences, to life sciences and to humanities and social sciences. Dr. Liao serves as the BESC Activity Lead for Butanol Production by CBP.
June 20, 2016
Discovery Of A Novel Molecular Mechanism Controlling Seed Physical Dormancy
Physical seed dormancy exists widely in higher plants, but its molecular mechanism has remained largely elusive. By screening a large number of Tnt1 retrotransposon-tagged Medicago truncatula lines, we identified non-dormant seed mutants from this model legume species. This study elucidated a novel molecular mechanism of physical dormancy and revealed a new role of class II KNOX genes.
June 20, 2016
Syringyl/Guaiacyl (S/G) Ratio In Lignin May Influence Quality Of Carbon Fiber Produced From Lignins
Current lignin-based carbon fiber using low-cost lignin precursors does not possess the mechanical properties required for many structural applications. Lignins with various syringyl/guaiacyl (S/G) ratios were isolated from Populus genotypes and subjected to rheological treatment at various temperatures and cooling conditions. Organosolv lignins extracted from genotypes with lower S/G ratios exhibited higher viscosity values and molecular weights with larger amounts of condensed structures following rheology treatment at relatively lower temperature; higher viscosity and molecular weight is known to provide for higher quality carbon fiber.
June 20, 2016
Improved Thermophilic Anaerobe Achieves High Biofuel Titers From Wood And Cellulose
This study demonstrates that thermophilic anaerobes are capable of producing ethanol at high yield and at titers greater than 60 g/L from purified substrates. However,challenges were encountered with existing fungal cellulases and inhibitors from pretreatment. The high titers and yields observed support the feasibility of using engineered thermophiles for industrial ethanol production if challenges associated with pretreatment inhibitors can be avoided.
June 07, 2016
Simultaneous Achievement Of High Ethanol Yield And Titer In Clostridium thermocellum
Adaptive evolution successfully improved the ethanol yield and the titer from a rationally engineered CBP strain. This evolved strain has the highest ethanol yield and titer reported to date for C. thermocellum, and is an important step in the development of this microbe for industrial applications.
June 01, 2016
Workshop Summary: Lessons From Industry In Commercializing Biotechnology
This article summarizes lessons learned drawn from the "Technology Challenges and Opportunities in Commercializing Industrial Biotechnology Workshop," September 28-29, 2015, San Diego.
May 09, 2016
A Bifunctional Ammonia-Lyase Is Critical In Grass Cell Wall Biosynthesis Of Lignin
Using phylogenetic, transcriptomic and in vitro biochemical analyses, a single homotetrameric cytosolic bifunctional ammonia-lyase (PTAL) was identified among eight BdPAL enzymes in the model grass species Brachypodium distachyon. 13C stable isotopic labelling experiments along with BdPTAL1-down-regulation in transgenic plants showed that the TAL activity of BdPTAL1 can provide nearly half of the total lignin deposited in grasses, with a significant preference for S-lignin and wall-bound coumarate biosynthesis.
April 29, 2016
Improved Whole Cell Wall NMR Measures Carbohydrate And Lignin Structures Without Derivatization
A new NMR solvent system composed of dimethylsulfoxide (DMSO-d6) and hexamethylphosphoramide (HMPA-d18) was developed to understand plant cell wall structures with minimal deconstruction and modification of biomass. The proposed bi-solvent system does not require derivatization or chemical modification, thus it facilitates easier sample preparation and less signal overlapping of correlation peaks compared to the traditional methods.
April 28, 2016
Identification And Overexpression Of Knotted1-Like Transcription Factor For Lignocellulosic Feedstock Improvement
Using transgenic approach, a switchgrass Knotted1 transcription factor, PvKN1 was overexpressed in switchgrass and transgenic plants were characterized for recalcitrance and growth-related traits. PvKN1 overexpression resulted in reduced lignin deposition/biomass recalcitrance and improved sugar release efficiency without affecting various growth parameters such as tiller height, tiller number, fresh and dry biomass.
April 28, 2016
Intellectual Property Impact of the BRCs
The Bioenergy Science Centers (BRCs) have generated over 500 invention disclosures, 328 patent applications (of which 45 have been awarded) which have led to 133 licenses or options with industry.
April 26, 2016
Development Of Improved Expression Plasmid In Clostridium thermocellum
Clostridium thermocellum is a promising candidate for ethanol production from cellulose biomass yet requires metabolic engineering to further improve ethanol yield. An expression plasmid was redesigned to improve transformation efficiency and structural stability. The new expression plasmid had both significantly higher transformation efficiency than its predecessor (~2x more), and was also able to more robustly express genes of interest.
April 26, 2016
New Genetic Markers Identified For Switchgrass Cell Wall Composition And Conversion
A full-sib switchgrass population was developed by crossing a lowland genotype (AP13) to an upland genotype (VS16). QTL associated with the traits of interest were identified. Significant variation for glucose, xylose and total sugar release, and lignin content (19-27%) in the population; a unit increase in lignin content reduced total sugar release by an average of 10 mg g-1; and QTL analysis detected nine genomic regions underlying sugar release and 14 for lignin content.
April 26, 2016
Structural Diversity Of Xylans Measured In Cell Walls Of Monocots
This study provides a new perspective on the diversity, function and evolution of monocot cell walls, enabling the manipulation of xylan structure and development of new technologies for the conversion of biomass from this important family of plants to yield commercially valuable and sustainable products.
April 25, 2016
BRCs Well Represented at Symposium on Biotechnology for Fuels and Chemicals
The Symposium on Biotechnology for Fuels and Chemicals (SBFC) was held April 25-28, 2016, in Baltimore, Maryland. As part of the overall symposium the combined Bioenergy Research Centers (BRCs) presented thirty-seven talks and twenty posters representing 25% of the talks and 10% of the posters.
April 18, 2016
Lignification And Recalcitrance Affected By Age And Season In Field-Grown COMT-Downregulated Switchgrass
Previous field and greenhouse studies have shown that COMT-downregulation in switchgrass decreases lignin content and reduces the S/G ratio, thereby lowering recalcitrance and improving ethanol yields. Trends in lignification and recalcitrance differ between growing seasons. Third-year results showed an increase in lignification and decrease in sugar release across the season. S/G ratios increased over time in non-transgenic control lines, but were relatively stable in COMT-downregulated lines. During early (elongation) growth stages, cell wall chemistry was similar between COMT-downregulated and control lines. After reaching the reproductive growth stage in July, COMT-downregulated lines maintained reduced lignin content, decreased S/G ratios, and improved sugar release through December. No differences in rust susceptibility were observed.
April 08, 2016
GreenWood Resources, Inc. Licenses BESC Invention For Lignin Regulator
Studies on the natural variation in lignin content in poplar trees identified a gene with major effects on lignin biosynthesis, the key polymer hindering efficient biomass digestibility. GreenWood Resources, Inc. has nonexclusively licensed this jointly-owned BESC invention and will continue to partner with ORNL as they complete field studies.
April 01, 2016
BioEnergy Science Center (BESC) Website Receives A "Distinguished Technical Communication" Award
The Washington-Baltimore Society for Technical Communication (STC) recognized the BioEnergy Science Center (BESC) website with the "Distinguished Technical Communication" award in April 2016.
March 30, 2016
Review: Using Microorganisms For The Production Of Next-Generation Biofuels
A review on how microorganisms can be exploited for the production of next-generation biofuels: a) based on the ability of bacteria and fungi to use lignocellulose; b) via direct CO2 conversion using microalgae; c) lithoautotrophs driven by solar electricity; or d) relying on the capacity of microorganisms to use methane generated from landfill.
February 05, 2016
Discovery Of New Enzyme System Sheds Further Light On High Cellulolytic Performance Of C. thermocellum
C. thermocellum utilizes not only all the cellulase degradation mechanisms known today (cellulosomes and free enzymes), but also a new category of scaffolded enzymes not attached to the cell. This discovery explains C. thermocellum's superior performance on biomass. These scaffoldins were found to be essential for the well known digestion mechanism, i.e., the defibrillation of plant cell walls.
February 04, 2016
Contribution Of Lignin Composition And Structure To Improvements In Bioprocessing Of Populus Using CBP
Populus variants with low and high syringyl to guaiacyl (S/G) ratios were hydrolyzed and fermented with Clostridium thermocellum under CBP conditions, and compared to conventional fungal enzymes and yeast. The composition and structure of cellulose and lignin in the biomass was correlated with the bioconversion results. Samples with a S/G ratio of 2:1 were converted more rapidly and to a greater extent than biomass with a 1:2 S/G ratio. The CBP microbe hydrolyzed biomass two to three times more readily than commercial fungal enzymes in either scenario. Lignin polymer size (lignin Mw) was found to be lower for the low S/G biomass.
January 12, 2016
Optimizing Biocatalyst-Feedstock Combinations to Achieve High Solubilization with Minimal Pretreatment
This study carried out the most comprehensive controlled comparison to date of lignocellulosic solubilization by various biocatalysts, and report initial exploration of enhancing microbial solubilization of cellulosic biomass via mechanical disruption (cotreatment). Trends drawn from time-course and end-point data for six conversion systems and three substrates were: greater-than-expected differences in the effectiveness of various biocatalysts; lower yields and greater dependence on particle size for Populus as compared to green or senescent switchgrass; equal fractional solubilization of glucan and xylan with no biological solubilization of the non-carbohydrate fraction of biomass; and two-fold increase in solubilization via mechanical disruption with greater benefits on partially-fermented feedstock.
January 06, 2016
Review: How Plant Cell Wall NMR Provides Insights Into Biomass Chemistry and Structures
The structure of the plant cell wall and recalcitrance are intimately tied together such that fundamental breakthroughs in recalcitrance have driven the science of biomass characterization. Work from BESC and other energy centers has dramatically enhanced the resolution and productivity of Nuclear Magnetic Resonance (NMR) analysis of biomass polymers including lignin, cellulose and hemicellulose. Whole cell NMR analysis, as reviewed in this article, provides a relatively facile means of characterizing changes in lignin and hemicellulose that contribute to reduced recalcitrance in pretreated biomass and/or transgenic or natural variant plant species.
December 31, 2015
Successful Transfer of Transgenic Switchgrass Low-Recalcitrance Traits into High-Yielding Field Variety
This study evaluated the feasibility of transferring the low-recalcitrance traits associated with a transgenic switchgrass line into high-yielding field varieties in an attempt to improve growth-related traits and to preserve the transgenic benefit. Our results provide insights into the possible improvement of switchgrass productivity via biotechnology paired with plant breeding.
December 31, 2015
BESC Biomass Improvements In Lignin Extended From Grasses To Eucalyptus
Lignin reduction through breeding and genetic modification has the potential to reduce costs in biomass processing. Previous work demonstrated that both C3′H and C4H down-regulated lines had lower S/G ratios, lignin and recalcitrance. Both lines have significantly higher extractability under NaOH base extraction, indicating altered cell wall construction. Although the C3′H contained more H lignin than the C4H and control samples, only slight reductions in average molecular weights of the lignin and few changes in the lignin subunit were observed.
December 29, 2015
Reducing Recalcitrance In Plants By Down-Regulating A Gene Involved In C1 Metabolism
Folylpolyglutamate synthetase (FPGS) genes and their corresponding mutants were characterized in Arabidopsis using cellular, biochemical, genomic and molecular approaches. Down-regulation of a single FPGS isoform leads to reduced lignin and altered hemicellulose in plants and therefore should be explored further for the improvement of lignocellulosic feedstocks.
December 26, 2015
Review: Potential Impact of S. vermifera, A Unique Root Symbiont, On Agronomics of Biofeedstocks
Research performed with orchid mycorrhizal fungus Sebacina vermifera clearly indicates significant growth-promoting abilities in a remarkably broad spectrum of plants, including switchgrass, that rivals or even surpasses that of arbuscular mycorrhizae. Sebacinoid fungi should be considered as a previously hidden, but amenable and effective microbial tool for enhancing plant productivity and stress tolerance which has been validated in switchgrass, an important biofeedstock for biofuels.