Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

A Better Route to Xylan

13.11.2012
Joint BioEnergy Institute Researchers Find New Access to Abundant Biomass for Advanced Biofuels

After cellulose, xylan is the most abundant biomass material on Earth, and therefore represents an enormous potential source of stored solar energy for the production of advance biofuels.

A major roadblock, however, has been extracting xylan from plant cell walls. Researchers with the U.S. Department of Energy (DOE)’s Joint BioEnergy Institute (JBEI) have taken a significant step towards removing this roadblock by identifying a gene in rice plants whose suppression improves both the extraction of xylan and the overall release of the sugars needed to make biofuels.

The newly identified gene – dubbed XAX1 – acts to make xylan less extractable from plant cell walls. JBEI researchers, working with a mutant variety of rice plant – dubbed xax1 – in which the XAX1 gene has been “knocked-out” found that not only was xylan more extractable, but saccharification – the breakdown of carbohydrates into releasable sugars – also improved by better than 60-percent. Increased saccharification is key to more efficient production of advanced biofuels.

“In identifying XAX1 as a xylan biosynthetic protein, the first enzyme known to be specific to grass xylan synthesis, we’ve shown that xylan can be modified so as to increase saccharification,” says Henrik Scheller, who heads JBEI’s Feedstocks Division and directs its Cell Wall Biosynthesis group, and also holds an appointment with Lawrence Berkeley National Laboratory (Berkeley Lab). “Our findings provide us with new insights into xylan synthesis and how xylan substitutions may be modified for increased biofuel generation.”

Scheller is a co-author of a paper describing this work that has been published by the Proceedings of the National Academy of Sciences (PNAS). The paper is titled “XAX1 from glycosyltransferase family 61 mediates Xylosyl transfer to rice xylan.” The corresponding author is Pamela Ronald, who holds joint appointments with JBEI and the University of California (UC) Davis. Other authors were Dawn Chiniquy, Vaishali Sharma, Alex Schultink, Edward Baidoo, Carsten Rautengarten, Kun Cheng, Andrew Carroll, Peter Ulvskov, Jesper Harholt, Jay Keasling and Markus Pauly.

As a source of transportation energy, advanced biofuels synthesized from lignocellulosic biomass in grasses and other non-food plants have the potential to replace fossil fuels that are responsible for the annual release of nearly 9 billion metric tons of excess carbon into the atmosphere. Unlike ethanol made from corn or sugarcane, advanced biofuels can be dropped into today’s vehicles with no impact on performance, and used in today’s infrastructures with no modifications required. Advanced biofuels are renewable and carbon-neutral, meaning their use does not add excess carbon to the atmosphere.

Xylan, like cellulose, is a major component of plant cell walls that serves as a valuable source of human and animal nutrition. Despite its importance, few of the enzymes that can synthesize xylan-type polysaccharides have been identified. It is believed that xylan plays an essential structural role in plant cell walls through cross-linking interactions with cellulose and other cell wall components.

“Xylan is of particular interest for the improvement of feedstocks for the generation of cellulosic biofuels, a currently expensive and inefficient process,” says Ronald.

“Xylan inhibits access of the enzymes that break down cellulose into sugars and is an additional substrate for cross-linking to lignin, all of which contributes to the recalcitrance of plant cell walls.”

Dawn Chiniquy was part of a research team that identified XAX1 as the first enzyme known to be specific to xylan synthesis in grasses.

To find genes important for grass xylan biosynthesis, Ronald, Scheller and their co-authors focused on the GT61 family of glycosyltransferases. GT61 enzymes have been identified through bioinformatics as being expanded in grasses and containing grass-specific subgroups. Working with rice plants, the standard plant model for studying grasses, they conducted a reverse genetics screen of 14 genes with insertional rice mutants that are highly expressed members of the GT61 family. This led them to the identification of a mutant plant they named xax1 because its mutation resulted in the function of the XAX1 being knocked-out.

“XAX1 adds a specific xylose sugar to the arabinose substitutions on the xylan chain that creates more cross-links between xylan and lignin, making the plant cell walls less amenable to the production of biofuels,” says Dawn Chiniquy, first author of the paper who is now with the Energy Biosciences Institute. “Without a functioning XAX1 gene, there were fewer cross-links with lignin, which made the xylan more extractable and also increased saccharification.”

Subsequent assays showed the rice xax1 mutant plants to be deficient in ferulic and coumaric acid, aromatic compounds whose residues on arabinose are known to promote cross-linking between xylan chains the lignin. On the down-side, the xax1 mutant did yield a dwarf phenotype, but Scheller says he and his colleagues have already found a way to avoid the dwarf phenotype.

“We can apply the same principle used to make rice plants more easily saccharified to bioenergy crops,” Scheller says. “With the ability to modify cross-linking between xylan and lignin by targeting a glycosyltransferase, we also now have a potentially important new biotechnological tool for grass biofuel feedstocks.”

This research was primarily funded by the DOE Office of Science.


JBEI is one of three Bioenergy Research Centers established by the DOE’s Office of Science in 2007. It is a scientific partnership led by Berkeley Lab and includes the Sandia National Laboratories, the University of California campuses of Berkeley and Davis, the Carnegie Institution for Science, and the Lawrence Livermore National Laboratory. DOE’s Bioenergy Research Centers support multidisciplinary, multi-institutional research teams pursuing the fundamental scientific breakthroughs needed to make production of cellulosic biofuels, or biofuels from nonfood plant fiber, cost-effective on a national scale. For more, visit www.jbei.org

Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov/.

Lynn Yarris | EurekAlert!
Further information:
http://www.lbl.gov

More articles from Power and Electrical Engineering:

nachricht Organic-inorganic heterostructures with programmable electronic properties
29.03.2017 | Technische Universität Dresden

nachricht Researchers use light to remotely control curvature of plastics
23.03.2017 | North Carolina State University

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Quantenkommunikation: Wie man das Rauschen überlistet

Wie kann man Quanteninformation zuverlässig übertragen, wenn man in der Verbindungsleitung mit störendem Rauschen zu kämpfen hat? Uni Innsbruck und TU Wien präsentieren neue Lösungen.

Wir kommunizieren heute mit Hilfe von Funksignalen, wir schicken elektrische Impulse durch lange Leitungen – doch das könnte sich bald ändern. Derzeit wird...

Im Focus: Entwicklung miniaturisierter Lichtmikroskope - „ChipScope“ will ins Innere lebender Zellen blicken

Das Institut für Halbleitertechnik und das Institut für Physikalische und Theoretische Chemie, beide Mitglieder des Laboratory for Emerging Nanometrology (LENA), der Technischen Universität Braunschweig, sind Partner des kürzlich gestarteten EU-Forschungsprojektes ChipScope. Ziel ist es, ein neues, extrem kleines Lichtmikroskop zu entwickeln. Damit soll das Innere lebender Zellen in Echtzeit beobachtet werden können. Sieben Institute in fünf europäischen Ländern beteiligen sich über die nächsten vier Jahre an diesem technologisch anspruchsvollen Projekt.

Die zukünftigen Einsatzmöglichkeiten des neu zu entwickelnden und nur wenige Millimeter großen Mikroskops sind äußerst vielfältig. Die Projektpartner haben...

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Das anwachsende Ende der Ordnung

Physiker aus Konstanz weisen sogenannte Mermin-Wagner-Fluktuationen experimentell nach

Ein Kristall besteht aus perfekt angeordneten Teilchen, aus einer lückenlos symmetrischen Atomstruktur – dies besagt die klassische Definition aus der Physik....

Im Focus: Wegweisende Erkenntnisse für die Biomedizin: NAD⁺ hilft bei Reparatur geschädigter Erbinformationen

Eine internationale Forschergruppe mit dem Bayreuther Biochemiker Prof. Dr. Clemens Steegborn präsentiert in 'Science' neue, für die Biomedizin wegweisende Forschungsergebnisse zur Rolle des Moleküls NAD⁺ bei der Korrektur von Schäden am Erbgut.

Die Zellen von Menschen und Tieren können Schäden an der DNA, dem Träger der Erbinformation, bis zu einem gewissen Umfang selbst reparieren. Diese Fähigkeit...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Industriearbeitskreis »Prozesskontrolle in der Lasermaterialbearbeitung ICPC« lädt nach Aachen ein

28.03.2017 | Veranstaltungen

Neue Methoden für zuverlässige Mikroelektronik: Internationale Experten treffen sich in Halle

28.03.2017 | Veranstaltungen

Wie Menschen wachsen

27.03.2017 | Veranstaltungen

 
VideoLinks
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Organisch-anorganische Heterostrukturen mit programmierbaren elektronischen Eigenschaften

29.03.2017 | Energie und Elektrotechnik

Klein bestimmt über groß?

29.03.2017 | Physik Astronomie

OLED-Produktionsanlage aus einer Hand

29.03.2017 | Messenachrichten