College Report

Belly of the yeast

By Benjamin Recchie, ABí03

Photography by Dan Dry

Yeast has been used for thousands of years to make bread, brew beer, and ferment wine. And if a group of Chicago undergraduates succeeds in its experiment, yeast might also be used to clean up toxic chemicals.

Their project is part of the International Genetically Engineered Machine (iGEM) competition, which introduces college students to the growing field of synthetic biology. Genetic engineering on a large scale, synthetic biology works to replicate not just an isolated gene or two but long sequences, enough to alter an organism’s functions radically.

The Massachusetts Institute of Technology–based competition began in 2004 with a $100,000 grant from the National Science Foundation as a way to develop and test standard components for synthetic biologists. A registry at MIT now includes about 4,000 standard parts, up from only a few dozen five years ago.

Nora Yucel, left, and her team work to engineer yeast to consume neurotoxins.

Just as a hobbyist might assemble a radio using standard pieces like resistors and diodes, each iGEM team takes uniform parts (plus a few of their own design, if they so choose) and inserts them into a living, single-celled organism, usually yeast or bacteria because they are simple, well-studied, and easy to manipulate.

Organizers expect 120 teams to submit entries for the October 30–November 2 judging. Spending at least ten weeks working full time over the summer, the students post their lab notes to a Web site, making the information available even to competitors. Judging is based not only on the success of each project but also on the innovation of new parts the team designs.
Incoming fourth-year biochemistry major Nora Yucel learned about iGEM by chance, while surfing the Web “wasting time during finals” during winter quarter 2008. Yucel and Parijata Mackey, a fourth-year who studies philosophy and neuroscience, recruited fellow students to compete last year.

The six-member team aims to reengineer yeast to consume neurotoxins, a class of dangerous chemicals that includes pesticides and nerve gas. The students plan to add standard components and their own creations to yeast genes, aiming for the yeast to turn a certain color when it detects the neurotoxin, to consume the neurotoxin, and to turn another color when it finishes.

Yeast modified this way would have practical uses, such as disposing of chemical weapons. The U.S. military disposes of its chemical weapons, like sarin and VX, by incineration, a process that releases dioxins and other chemicals into the environment. “Instead of burning it, you could throw a bunch of yeast on it,” says Yucel. The yeast would glow red when it had consumed all the nerve gas, shrivel up, and be eaten by some other organism, with no toxic byproducts. And yeast is safe, can be freeze-dried for storage, and requires no special caution in handling. “There’s nothing malignant about yeast.”

Developing a marketable product isn’t far-fetched. Last year’s winning project, a Slovenian attempt to make a vaccine against the bacteria that causes stomach ulcers, is being considered for clinical trials. So when the teams submit their projects for judging, Chicago hopes its yeast will rise.

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