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 Mission possible: This device will self-destruct when heated
22.05.2015 | University of Illinois at Urbana-Champaign

nachricht Gamma ray camera may help with Fukushima decontamination*
21.05.2015 | Waseda 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: Kieler Forschende bauen die kleinsten Maschinen der Welt

Die DFG stellt Millionenförderung für die Entwicklung neuartiger Medikamente und Materialien an der Christian-Albrechts-Universität zu Kiel (CAU) bereit.

Großer Jubel an der Christian-Albrechts-Universität zu Kiel (CAU): Wie die Deutsche Forschungsgemeinschaft (DFG) heute (Donnerstag, 21. Mai) bekannt gab,...

Im Focus: Basler Physiker entwickeln Methode zur effizienten Signalübertragung aus Nanobauteilen

Physiker haben eine innovative Methode entwickelt, die den effizienten Einsatz von Nanobauteilen in elektronische Schaltkreisen ermöglichen könnte. Sie entwickelten dazu eine Anordnung, bei der ein Nanobauteil mit zwei elektrischen Leitern verbunden ist. Diese bewirken eine hocheffiziente Auskopplung des elektrischen Signals. Die Wissenschaftler vom Departement Physik und dem Swiss Nanoscience Institute der Universität Basel haben ihre Ergebnisse zusammen mit Kollegen der ETH Zürich in der Fachzeitschrift «Nature Communications» publiziert.

Elektronische Bauteile werden immer kleiner. In Forschungslabors werden bereits Bauelemente von wenigen Nanometern hergestellt, was ungefähr der Grösse von...

Im Focus: Basel Physicists Develop Efficient Method of Signal Transmission from Nanocomponents

Physicists have developed an innovative method that could enable the efficient use of nanocomponents in electronic circuits. To achieve this, they have developed a layout in which a nanocomponent is connected to two electrical conductors, which uncouple the electrical signal in a highly efficient manner. The scientists at the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have published their results in the scientific journal “Nature Communications” together with their colleagues from ETH Zurich.

Electronic components are becoming smaller and smaller. Components measuring just a few nanometers – the size of around ten atoms – are already being produced...

Im Focus: Phagen übertragen Antibiotikaresistenzen auf Bakterien – Nachweis auf Geflügelfleisch

Bakterien entwickeln immer häufiger Resistenzen gegenüber Antibiotika. Es gibt unterschiedliche Erklärungen dafür, wie diese Resistenzen in die Bakterien gelangen. Forschende der Vetmeduni Vienna fanden sogenannte Phagen auf Geflügelfleisch, die Antibiotikaresistenzen auf Bakterien übertragen können. Phagen sind Viren, die ausschließlich Bakterien infizieren können. Für Menschen sind sie unschädlich. Phagen könnten laut Studie jedoch zur Verbreitung von Antibiotikaresistenzen beitragen. Die Erkenntnisse sind nicht nur für die Lebensmittelproduktion sondern auch für die Medizin von Bedeutung. Die Studie wurde in der Fachzeitschrift Applied and Environmental Microbiology veröffentlicht.

Antibiotikaresistente Bakterien stellen weltweit ein bedeutendes Gesundheitsrisiko dar. Gängige Antibiotika sind bei der Behandlung von Infektionskrankheiten...

Im Focus: Die schreckliche Schönheit der Medusa

Astronomen haben mit dem Very Large Telescope der ESO in Chile das bisher detailgetreueste Bild vom Medusa-Nebel eingefangen, das je aufgenommen wurde. Als der Stern im Herzen dieses Nebels altersschwach wurde, hat er seine äußeren Schichten abgestoßen, aus denen sich diese farbenfrohe Wolke bildete. Das Bild lässt erahnen, welches endgültige Schicksal die Sonne einmal ereilen wird: Irgendwann wird aus ihr ebenfalls ein Objekt dieser Art werden.

Dieser wunderschöne Planetarische Nebel ist nach einer schrecklichen Kreatur aus der griechischen Mythologie benannt – der Gorgone Medusa. Er trägt auch die...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

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

TU Darmstadt: Gipfel der Verschlüsselung - CROSSING-Konferenz am 1. und 2. Juni in Darmstadt

22.05.2015 | Veranstaltungen

Internationale neurowissenschaftliche Tagung

22.05.2015 | Veranstaltungen

Biokohle-Forscher tagen in Potsdam

21.05.2015 | Veranstaltungen

 
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Nanogefäß mit einer Perle aus Gold

22.05.2015 | Biowissenschaften Chemie

Ferngesteuerte Mikroschwimmer: Jülicher Physiker simulieren Bewegungen von Bakterien an Oberflächen

22.05.2015 | Physik Astronomie

Was Chromosomen im Innersten zusammenhält

22.05.2015 | Biowissenschaften Chemie