Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Purdue Yeast Makes Ethanol from Agricultural Waste More Effectively

29.06.2004


A strain of yeast developed at Purdue University more effectively makes ethanol from agricultural residues that would otherwise be discarded or used as animal feed, and the first license for the yeast has been issued to the biotechnology company Iogen Corp.



Purdue’s genetically altered yeast allows about 40 percent more ethanol to be made from sugars derived from agricultural residues, such as corn stalks and wheat straw, compared with "wild-type" yeasts that occur in nature.

The agricultural residues are primarily made up of cellulose and "hemicellulose," which are known as cellulosic materials. Unlike traditional ethanol feedstocks, such as corn kernels, the cellulosic materials contain two major sugars, glucose and xylose, which cannot both be fermented into ethanol by natural Saccharomyces yeast, the microorganism used by industry to produce ethanol, said Nancy Ho, a senior research scientist and leader of the molecular genetics group in Purdue’s Laboratory of Renewable Resources Engineering, or LORRE. Iogen specializes in producing ethanol from cellulosic material.


A team led by Ho developed the more efficient yeast during the 1980s and 1990s. Conventional yeast can ferment glucose to ethanol, but it cannot ferment xylose. Xylose makes up about 30 percent of the sugar from agricultural residues, and the inability to ferment xylose would represent a major loss of ethanol yield, Ho said.

The Purdue researchers altered the genetic structure of the yeast so that it now contains three additional genes that make it possible to simultaneously convert glucose and xylose to ethanol. The ability to ferment xylose increases the yield of ethanol from straw by about 40 percent. Being able to simultaneously ferment glucose and xylose is important because both sugars are found together in agricultural residues, Ho said.

"It would cost too much money to separate the two sugars before proceeding with fermentation to ethanol, so being able to ferment both sugars together to ethanol is critical," she said. "To be more cost competitive with gasoline, the two sugars have to be converted together to ethanol.

"Until we developed our yeast, no suitable microorganism could convert these two sugars together."

Iogen has obtained a non-exclusive license from the Purdue Research Foundation for the yeast and related patents. Its Ottawa, Canada, demonstration facility is the first plant in the world to produce ethanol from cellulosic materials. Iogen is using the Purdue yeast to produce ethanol from the sugars the company derives from wheat straw.

"We have confirmed that Purdue’s recombinant glucose- and xylose-fermenting yeast is the most effective microorganism available for the production of ethanol from cellulosic materials," said Jeffrey S. Tolan, senior research scientist for Iogen. "The ethanol yield and productivity from the Purdue yeast in our plant matches that obtained by Dr. Ho’s group in the lab at Purdue. The Purdue yeast is also easy to work with and is favored by our plant operators because of this."

The ethanol made in Iogen’s plant is blended into gasoline at the Petro-Canada refinery in Montreal. Cars use the ethanol-gasoline blend without any modifications; typically, drivers are not even aware of the presence of the ethanol, except for the label on the gas pump. The Ottawa plant represents the latest step toward Iogen’s goal of making ethanol from cellulosic materials widely available as a fuel, Tolan said.

In Iogen’s process, about two-thirds of the straw is converted to ethanol, with a yield of about 75 gallons of ethanol per ton of straw. Most of the remaining one-third of the agricultural residue, which cannot be fermented, is burned to generate power to run the plant, and there is little waste or use of fossil fuels, he said.

"The use of cellulose ethanol offers advantages to the environment that are not obtained with other transportation fuels that are available," Tolan said.

Also known as ethyl alcohol, ethanol can be used as fuel by itself or blended with gasoline. The Purdue yeast is used in combination with other technologies under development that first convert agricultural materials to xylose and glucose, said Purdue’s Michael Ladisch, Distinguished Professor of Agricultural and Biological Engineering and director of LORRE.

"Iogen’s efforts are beneficial to companies in Indiana and elsewhere in the United States by providing an industrial test bed for the fermentation part of the cellulose conversion technology, hence speeding its development for uses on a range of crops and crop residues once the other technologies, including preprocessing of the cellulosic materials and converting these materials to sugars, are developed and proven in the industry," Ladisch said.

Ethanol is environmentally friendly and a cleaner fuel than gasoline, he said.

"The carbon dioxide that is generated from burning ethanol is recycled back into plant material because plants incorporate CO2 into cellulose as part of the photosynthesis cycle," Ladisch said. "This reduces the net generation of the greenhouse gas since part of it is recycled."

Ethanol currently is produced when yeast ferments glucose and related hexose - or six-carbon sugars in food crops such as cane sugar, corn and other starch-rich grains. However, Ho said, because these crops are expensive and in relatively limited supply, they can’t yield sufficient amounts of ethanol for transportation needs.

Cellulosic materials represent an opportunity to address this problem, she said. Cellulosic materials cost only about half as much as corn per ton but are more difficult than corn to convert to ethanol. Part of the difficulty is the fermentation to ethanol of the xylose, which is a five-carbon sugar. This sugar is not naturally fermented by yeast or other microorganisms.

"Corn-based ethanol production in the United States currently is about 3 billion gallons per year," Ho said. "According to conservative estimates, 30 percent of the residue left behind in the cornfield after harvest could produce another 4 billion to 5 billion gallons annually.

"The use of cellulosic materials also could open up new markets for crops such as grasses, which can be grown on marginal lands, creating jobs and providing more energy independence."

An added advantage of yeast strains developed by Ho is that they are based on environmentally safe Saccharomyces yeast, which has been used for centuries to make wine and bread and is the only microorganism used by industry for large-scale ethanol production from glucose.

Ho has worked for 20 years to produce and perfect a yeast that can effectively convert more of the sugars in plant matter - corn stalks, tree leaves, wood chips, grass clippings, and even cardboard - into ethanol.

"Ethanol produced from cellulosic materials is an ideal, domestically available fuel," Ho said.

In 1993, Ho’s group became the first in the world to produce a genetically engineered Saccharomyces yeast that can effectively ferment both glucose and xylose.

Ho’s research has been funded by the U.S. Department of Agriculture, the Department of Energy, the Consortium for Plant Biotechnology Research Inc., the U.S. Environmental Protection Agency and industry sources.

Ho holds a doctoral degree in molecular biology from Purdue, a master’s degree in organic chemistry from Temple University and a bachelor’s degree in chemical engineering from the National Taiwan University.

| newswise
Further information:
http://www.purdue.edu

More articles from Power and Electrical Engineering:

nachricht Did you know that the wrapping of Easter eggs benefits from specialty light sources?
13.04.2017 | Heraeus Noblelight GmbH

nachricht To e-, or not to e-, the question for the exotic 'Si-III' phase of silicon
05.04.2017 | Carnegie Institution for Science

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>