Biomass Formation and Modification
Biomass Deconstruction and Conversion
Genome-Wide Association Study (GWAS) Dataset Released
The GWAS dataset comprises more than 28 million single nucleotide polymorphisms, or SNPs, derived from approximately 882 resequenced poplar genotypes. Each SNP represents a variation in a single DNA nucleotide, or building block, and can act as a biological marker, helping scientists locate genes associated with certain characteristics, conditions, or diseases. [Image courtesy ORNL]Read More
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
Arthur J. Ragauskas receives Professional Achievement Award from The American Institute of Chemical Engineers
Brian H. Davison receives the Society for Industrial Microbiology and Biotechnology Fellowship
October 11, 2017
Review : Lignocellulose deconstruction in the biosphere
The aims of this review were to provide a better understanding of carbon recycling in the biosphere ranging from biomass synthesis to deconstruction by biotic or abiotic routes; highlight the importance of the synergism between natural microbial communities within a given ecosystem; and show the complexity of the biomass deconstruction mechanisms that have evolved in nature.
August 29, 2017
Schematic and TEM micrograph of the cellulose deconstruction mechanism of CelA. The GH48 and GH9 cat (...more)
Hyper Thermophilic Cellulase CelA from C. bescii Indifferent to Level of Crystallinity in Biomass
CelA was shown to break down cellulose with high crystallinity to the same extent as low crystallinity cellulose — a characteristic never reported for other cellulases. CelA exhibits a cavity forming mechanism on all types of biomass tested. This discovery demonstrates that nature's strategies for biomass conversion are diverse and that enzymes with new characteristics can still be discovered and isolated for improving biomass deconstruction applications.
August 28, 2017
Net ethanol and acetate production from the wild type C. thermocellum strain (Cth_WT) and a m (...more)
Enchi Corporation Licenses Joint Dartmouth College and ORNL Technology
"Engineered microbe could potentially move the payback period for a commercial cellulosic ethanol operation from 15 years down to two years," Bill Brady, Enchi CEO.
August 01, 2017
Society for Industrial Microbiology and Biotechnology (SIMB) Awardees in BESC–2017
Brian H. Davison, Chief Scientist for Systems Biology and Biotechnology in the Bioscience Division at ORNL and the Science Coordinator in BESC, awarded SIMB Fellow 2017. Fellowship status is a special grade of membership in SIMB, acknowledging a career-long sustained record of significant research and/or service contributions to the profession of industrial microbiology and/or biotechnology.
Amanda Williams-Rhaesa, a fifth-year Ph.D. candidate in Biochemistry and Molecular Biology at the University of Georgia (Dr. Michael Adams' lab), received a 2017 SIMB Diversity Travel Award.
July 18, 2017
Mechanism of Fucosylation in Xyloglucan Biosynthesis revealed in Arabidopsis thaliana
FUT1 is a plant fucosyltransferase that carries out the final step in the synthesis of the hemicellulose xyloglucan, which is a major component of the plant cell wall and is involved in cell growth and expansion, energy metabolism, and signaling. X-ray crystallography revealed the structural architecture of FUT1 in complex with bound donor and acceptor substrate analogs, forming the basis for in silico studies that unraveled the mechanistic basis for fucosylation in GT37 enzymes. Structural and mutagenic analyses determined that there was no active site amino acid residue that could act as a base for catalyzing the reaction. In silico studies revealed the presence of a crucial water molecule that could conduct catalysis by shuttling the proton to enable a SN1-like mechanism.
July 14, 2017
Comprehensive Assessment of Glycosyl Residue Composition Analysis Methods
This is the first paper that provides side-by-side comparison of the efficacy of four different established methods in the analysis of glycosyl residue composition of cell walls from both primary wall-enriched leaf tissues and secondary wall-enriched wood/stem tissues of both dicot (Arabidopsis, Populus) and grass (rice, switchgrass) species.
July 11, 2017
2017 BESC Science Retreat
The Year 10 BESC Science Retreat was in Chattanooga, Tennessee from July 11-13, 2017 with 165 attendees from 13 BESC partner institutes.
July 05, 2017
Engineering T. saccharolyticum Ethanol Pathway into C. thermocellum Improves Biofuel Production
Clostridium thermocellum is a candidate for ethanol production from cellulose, but requires metabolic engineering to improve yield and titer. Thermoanaerobacterium saccharolyticum was previously engineered to produce ethanol at high yield and titer. Four of the genes that are responsible for ethanol production are adhA, nfnA/B, and adhEG544D. Introducing the T. saccharolyticum genes into C. thermocellum significantly increased ethanol yield.
July 03, 2017
Linking Overflow Metabolism and Growth Cessation in C. thermocellum
Findings of growth cessation and overflow metabolism provide metabolic engineering and fermentation strategies for high substrate loading fermentations to achieve high product yields.
June 19, 2017
Improving Bioavailability of Carbohydrate to C. bescii in Natural and Transgenic Switchgrasses
The bioavailability of carbohydrates to C. bescii was evaluated in the switchgrass lines unmodified Cave-in-Rock (CR), transgenic COMT-KD and Myb4-OE, and their corresponding parental lines. Each switchgrass line was examined as either hydrothermally treated (180ºC for 25 min) or untreated. C. bescii growth and carbohydrate solubilization (cellulose and hemicellulose) were determined for each treatment scheme (microbial, hydrothermal, or a combination of both). While C. bescii could significantly solubilize the transgenic switchgrass lines, including Cave-in-Rock, hydrothermal treatment was needed to solubilize 50% or more of the carbohydrate content.
May 01, 2017
Jonathan Mielenz, retired researcher from ORNL and BESC, was awarded the 2017 Charles D. Scott award (...more)
BRCs well represented at 39th Symposium on Biotechnology for Fuels and Chemicals
As part of the overall symposium the three DOE BRCs presented a combined total of twenty-two talks, including two as collaborations between the BRCs, and thirty-nine posters representing 28% of the talks and 15% of the posters. The presentations and posters highlighted the accomplishments, as well as common challenges in organization and research, in carrying out impactful mission-directed R&D in bioenergy.
May 01, 2017
New Insights On Recalcitrance From Lignin Inhibition Of Microbial Deconstruction
Microbial solubilization of biomass selectively targets carbohydrates. Clostridium thermocellum, a highly effective cellulolytic microbe, can hydrolyze ~93% of 100gL-1 pure cellulose. The microbe solubilizes only partially hydrolyzes cellulose in untreated energy crops. Techniques used were quantitative fluorescence colocalization analysis and surface chemical imaging. Quantitative evidence for the cause of feedstock recalcitrance: depletion of surface carbohydrate increases lignin exposure which leads to inhibition of enzymatic activity, while the bulk residual biomass retains significant undigested sugar content. Limited hydrolysis is not caused by inhibitory hydrolyzed sugars nor fermentation products (i.e., ethanol).
April 17, 2017
Photos of the field experiments in the first (2013), second (2014), and third (2015) growing seasons (...more)
Multi-Year Study Of Transgenic Switchgrass Plants In Regulation Shows Improved Yield And Dependency On Expression Levels
Four promising lines with moderate or low microRNA (miR156) overexpression from prior greenhouse study were selected for a field experiment to assess miR156 expression levels and biomass yields over three years. The best performing line consistently produced more biomass (25-56%) than the control in all three seasons, which translated to the production of 30% more biofuel per plant in the final season. Transgenic plants with modifications to transcriptional regulators, which impact such a broad range of genes, will likely require more extensive field evaluations than those with single and simple trait gene modifications to evaluate the stability of the desired growth phenotypes.
April 12, 2017
First-Of-A-Kind Study Of Thermophilic CBP With Cotreatment
Milling during lignocellulosic fermentation (or cotreatment) is an alternative to thermochemical pretreatment to enhance biological solubilization of lignocellulose. Carbohydrate solubilization was measured in consolidated bioprocessing with Clostridium thermocellum with cotreatment or with hydrothermal pretreatment. High carbohydrate solubilization was demonstrated without thermochemical pretreatment and added saccharolytic enzymes. C. thermocellum appears able to attack all the major linkages in cellulosic biomass provided that these linkages are accessible. The ability of C. thermocellum to withstand high intensity milling supports the feasibility of cotreatment. Less modified lignin may foster production of value-added coproducts.
March 27, 2017
Use of Caldicellulosiruptor saccharolyticus as a biological probe to report on changes in recalcitrance of plant biomass
C. saccharolyticus whole genome microarrays were used to access the transcriptome when grown on purified polysaccharides and chemically pretreated or genetically modified lignocellulosic substrates. Differential regulation of carbohydrate degradation, transport, and metabolism genes in C. saccharolyticus can be used to assess the availability of various plant polysaccharides to the microbe. This allows for inferences about the consequences of a chemical pretreatment or genetic modification of lignocellulose with an eye towards biofuels production.
March 21, 2017
Improving Pretreatment Inhibitor Tolerance in Clostridium thermocellum
Bioconversion performance in the presence of common pretreatment inhibitors was improved through targeted strain engineering thus reducing barriers to achieving a robust consolidated bioprocessing strategy with Clostridium thermocellum.
March 21, 2017
CBP-CT: an R&D-Driven Innovation with Potential for Disruptive Reductions in the Cost of Cellulosic Biofuels
Compared to current technology, the CBT-CT scenario was projected to offer 4.6-fold greater annual revenue, as well as 8-fold shorter payback period, and feasibility at ~10-fold smaller scale. CBT-CT is a potentially disruptive technology and a powerful, though still speculative, example of the potential benefits of including new-paradigm as well as in-paradigm innovation in R&D portfolios.
March 18, 2017
Overexpression of DUF266 can significantly enhance both cellulose and biomass in Populus
(BESC's 900th publication)
Little is known about the function of Domain of Unknown Function 266 (DUF266)-containing proteins and no DUF266 protein has been characterized in Populus. A bioinformatics approach was taken to identify all DUF266 proteins in Populus and their relationship with their homologs in other species. A transgenic approach was used to determine the function of one member of DUF266 proteins in Populus (PdDUF266A). The resulting phenotypes make PdDUF266A a promising target for genetic manipulation for improving biomass quality.
March 10, 2017
Use of Photoacoustic AFM to Spatially Resolve Nanomechanics of Plant Cell Wall Delignification
By chemically processing biomass and employing emerging nanometrology techniques, the various stages of lignin removal may be distinguished through the observation of morphochemical and nanomechanical variations. The cell wall nanomechanical properties undergo quantifiable reductions in plasticity, adhesion energy, and elasticity. These quantitative observations can be used to characterize delignification. The observed reduction in plasticity seems counterintuitive considering that lignin adds to cell wall rigidity.
February 27, 2017
Microbial Attachment to Cellulose Substrate Produces Widespread Gene Expression Changes
Unlike the majority of biofilm forming bacteria, C. thermocellum adheres to substrata that also provide its major carbon and energy sources. Before this study, discrete omics analyses of biofilm and planktonic cell populations had not been performed. Cellulolytic bacterial cells that evolved to thrive on solid carbon sources were shown to thoroughly alter expression of their central metabolism, anabolism, and homeostatic functions in response to the availability of solid attachment interfaces and solubilizable carbohydrates. The attached bacteria were functionally strong in growth and biomass conversion, while the planktonic cells were stressed and motile due to low available substrates.