sealPurdue News

September 1998

Purdue innovations named in top 100 new technologies

WEST LAFAYETTE, Ind. --Two Purdue University research groups have won R&D 100 Awards from R&D Magazine for developing new technologies that may help the environment.

The awards will be given at a Sept. 24 banquet at Chicago's Museum of Science and Industry to the developers of the year's 100 most technologically significant products and processes.

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One of the winning technologies was developed by a team led by Nancy Ho, a Purdue molecular geneticist, who modified the genes of a particular type of yeast so that the tiny organism can convert agricultural wastes into ethanol. The modified yeast may someday provide car drivers with an inexpensive, clean-burning fuel and farmers with a new market for crop residues.

The other winner from Purdue is a device designed to quickly and easily identify plastics so they can be sorted for recycling. It was developed by a group led by Edward Grant and Dor Ben-Amotz, professors of chemistry. Grant says it may help recycle billions of pounds of plastics a year.

Twenty-year effort pays off

Ho and her colleagues in the Molecular Genetics Group at Purdue's Laboratory of Renewable Resources Engineering (LORRE) won the award for their work with SWAN Biomass Co., Oakbrook Terrace, Ill., to develop the genetically modified yeast. Geneticist Zhengdao Chen and technician Adam Brainard, members of Ho's research group, also contributed to the development of the yeast.

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

Ethanol, a form of alcohol, is a liquid fuel that can be used by itself or blended with gasoline to create "gasohol." When burned, ethanol produces far less air pollution and greenhouse gases than gasoline. Currently, ethanol is produced when yeast ferments the glucose, a form of sugar, in food crops such as cane sugar, corn and other starch-rich grains. However, Ho says, these crops are expensive and in limited supply, making them too costly to produce ethanol on a large scale.

The genetically engineered yeast produces at least 30 percent more ethanol from a given amount of plant material than the unmodified version of the yeast or any other yeast. It does not need to be grown in special nutrients or under special conditions. And it can use agricultural and other organic wastes -- an abundant, completely renewable domestic resource -- rather than food crops, Ho says.

"This plant material is an ideal and inexpensive feedstock for ethanol fuel production," Ho says. "This genetically engineered yeast will make it possible to substantially lower the cost of producing ethanol on a large scale. The goal is to make ethanol not only competitive with the cost of gasoline at the pump, but even much cheaper. Using ethanol produced from plant wastes not only will reduce our country's dependence on foreign oil, but, because it is clean-burning, it also will reduce air pollution and greenhouse gas emissions from cars."

The yeast that Ho modified, called Saccharomyces yeast, is an environmentally safe microorganism commonly used by industry to ferment glucose into ethanol. It also has been used since ancient times to make wine. But glucose is only one type of sugar in plant matter. Beginning in the early 1980s, Ho's research group and others around the world attempted to genetically modify the yeast so that it could ferment both glucose and another plant sugar, xylose, into ethanol. A yeast that could ferment both sugars could produce more ethanol from the same amount of plant material.

Over several years, all the U.S. research groups gave up pursuing a yeast that could ferment both glucose and xylose, but Ho's group and three other international groups continued.

"I stayed with this project because I thought it was workable, and I was interested in 'green' chemistry," Ho says. "It's a subject that I feel strongly about."

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.

Amoco Corp. licensed the yeast strain. SWAN Biomass Co., a subsidiary of Amoco, was established to develop the yeast for commercial applications.

Ho's research has been funded by the Department of Energy through the Consortium for Plant Biotechnology Research Inc.; the U.S. Environmental Protection Agency; and industry, including SWAN Biomass.

New probe brightens recycling efforts

Grant and his colleagues at Purdue drew upon technologies used in their laboratories to develop the new device, called the RP-1 Polymer Identification System, which will allow commercial and community recyclers to easily identify and sort a wide range of plastics. The device is being manufactured by SpectraCode Inc. of West Lafayette, a business founded in 1994 by Ben-Amotz, Grant, and Yanan Jiang, a Purdue research scientist.

Co-inventors sharing the award are Kenneth Haber, manager of the chemistry department's laser facility, and George Laurence, a senior from West Lafayette who is majoring in chemistry.

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Though plastics recycled from milk jugs are often used to develop new consumer goods, the plastics in many products are hard to sort or identify. In addition, billions of pounds of plastics are landfilled or incinerated every year because they have been contaminated with plastics that cannot be recycled, Grant says.

"Polymers of different composition are incompatible when melted together, and a ton of mixed plastic is a ton of garbage," Grant says.

Research leading to the RP-1 device was supported by the Environmental Protection Agency and the Ford Motor Co.

"The device can be used to sort plastic components in cars, synthetic fiber resins in carpets, and a number of plastics used in the building and construction industry, such as those used for window frames or pipes," Grant says. "It also can be used to sort plastic films, such as those found in dry cleaning bags, shrink wrap and packaging material."

Only a small fraction of these materials currently are recycled, primarily because of difficulties in identifying and separating the various types of plastics, Grant says.

The RP-1 consists of a hand-held probe, which looks similar to a hair dryer, connected to a mobile console. Samples of plastic are illuminated with a laser in the hand-held probe, and the light scatters in a pattern that is specific for each type of plastic. The scattered light is recorded and analyzed by a computer, which identifies the type of plastic and displays the result on a monitor on the console.

The entire identification cycle requires less than one second. Used with an automated system designed to trigger the probe when plastics are placed on a conveyor belt, the SpectraCode device is capable of identifying the chemical composition of plastic parts and scrap at rates of more than 100 pieces per second, or 500 tons per day, Grant says. It could be used to screen commercial and post-consumer waste in factories, warehouses, recycling centers and scrap yards, Grant says.

SpectraCode has installed RP-1 systems at two large-scale recycling facilities and in the Detroit Vehicle Recycling Development Center, a joint research facility of the Big Three automakers.

Visteon, Ford Motor Co.'s automotive component operations, has supported development of the SpectraCode device and is using the product in its recycling efforts. The new device also was part of Lincoln-Mercury's environmental exhibit at the 1998 North American International Auto Show.

As full-time faculty members, Ben-Amotz and Grant play mainly advisory roles in the operation of SpectraCode.

"In some ways, I see my work at SpectraCode as a small extension of the job I do as an academic research director," Grant says. "Developing and marketing a technological product is similar to the process of generating new scientific knowledge and successfully selling it in the marketplace of ideas. The experience that I have gained at SpectraCode has made me a more effective, more relevant teacher and a better manager of resources for my graduate students."

Purdue undergraduates have benefited directly from the university's connection with SpectraCode. Last semester, chemistry major Andrew Parker of Largo, Fla., carried out an undergraduate research project at SpectraCode, developing a new process for analyzing black plastics.

"It is exciting to do cutting-edge research and at the same time feel that your work has immediate industrial impact," Parker says. "There is a lot here that I have learned about the interface between science and business and how they support each other. This should give me an edge in the job market when I leave Purdue."

SpectraCode also has served as a laboratory for students from Purdue's Krannert Graduate School of Management. Last spring, second-year MBA students Brett Staker of Lafayette , Francois Callait of Albuquerque, N.M., and Stephen Schultz of Indianapolis analyzed the market for the RP-1 as a project for their management class. Summer students in a marketing strategy class studied the prospects for selling a portable variant of the RP-1 for other uses.

Sources: Edward Grant, (765) 494-9006; e-mail,

Nancy Ho, (765) 494-7046; e-mail,

Robert Walker, SWAN Biomass Co., (630) 889-7126

Writer: Susan Gaidos, (765) 494-2081; e-mail,

Purdue News Service: (765) 494-2096; e-mail,

A genetically engineered yeast developed at Purdue's Laboratory of Renewable Resources Engineering can produce at least 30 percent more ethanol from plant material than its unmodified parent yeast or any other yeast. Nancy Ho, group leader for molecular genetics and the lab's senior research scientist, holds cultures of the new yeast strain (in the petri dish) and a sample of ethanol. (Purdue News Service Photo by David Umberger)
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Purdue Professor Edward Grant uses a device he helped develop to identify the plastic backing on an automobile headlight. The new device, named by R&D Magazine as one of the year's most technologically significant products, can identify plastics so they can be sorted for recycling, including plastics that are currently impossible or hard to sort. (Purdue News Service Photo by David Umberger)
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