Genetically Engineered Machine competition

[[GAFnews] Science Online]

http://www.technologyreview.com/read_article.aspx?id=17716&ch=biotech

Bizarre Bacterial Creations

Banana-scented bacteria, engineered to order, are just one offering at
this weekend's International Genetically Engineered Machine competition.
By Emily Singer

E. coli bacteria engineered to smell like ripe bananas are just one of
the designed biological devices to be presented at this weekend's
synthetic-biology competition.

Anyone who has ever smelled E. coli bacteria knows that they smell
bad. Putridly bad. So, a group of student bioengineers at MIT set out
to sweeten the scent of this commonly used lab bacteria. The team
constructed its creation from a collection of biological "parts"--bits
of DNA that, when inserted into living organisms, can make the
organisms glow, detect light, and perform a number of other unusual
functions. The team will showcase its sweet-smelling bug this weekend
at the International Genetically Engineered Machine competition (iGEM)
at MIT, along with 37 other student groups from around the world.

While the projects are executed largely by undergraduate students
(with guidance from faculty and graduate-student advisors), the
designs represent some of the most complex biologically engineered
machines to date--and they promise to further the field of synthetic
biology, a newly emerging discipline that views living systems from an
engineering point of view.

The MIT team, for example, tosses out wacky applications for its
technology: minty-fresh foot fungus or baker's yeast that smells of
bananas. But its real goal is the construction of functional
biological parts. "The key idea here is to develop a library of
composable parts which we think of in the same way as Lego blocks,"
says Tom Knight, an engineer at MIT who cofounded the competition with
MIT bioengineer Drew Endy. (Both advise the MIT team.) "These parts
can be assembled into more-complex pieces, which in many cases are
functional when inserted into living cells."

To create the scented bacteria, the students looked for different
genes that convert chemicals naturally made by bacteria into chemical
precursors of aromatic compounds, as well as genes that convert the
precursors to the aromatics themselves -- methyl salicylate, commonly
known as oil of wintergreen, and isoamyl acetate, a component of the
ripe-banana smell. The genes were then hooked up to genetic
controllers, known as promoters, which determine when and where that
gene is turned on. A gene from a plant, for example, might be
controlled by a promoter from bacteria.

The various DNA components, collected from fellow scientists and from
a genetic repository housed at MIT, were then embedded in a circular
string of DNA and inserted into bacteria. The end result is a new
strain of E. coli that smells of mint and bananas. The team also
eliminated the gene responsible for E. coli's natural stink.

One of the most important goals of the competition is to stock the
shelves of the Registry of Standard Biological Parts, a sort of
hardware store of genetic parts housed at MIT. "The idea is to
standardize parts and the way they are put together, in the same way
electrical and mechanical parts are standardized," says Knight. "And
to be able to give people a reasonable assurance that the parts, when
put together, will function as they were designed to." During the
course of its project, the MIT team has deposited about a dozen newly
made parts into the registry for use by other members of the
synthetic-biology community.

As the number and complexity of parts grow, both students and industry
and academic scientists can make ever-more-complicated designs. The
machines entered in the 2006 iGEM competition have doubled in size in
the past two years, from about 6,000 to 12,000 letters of DNA. "These
[projects] represent the largest designed genetic systems that have
ever been developed," says Chris Voigt, a bioengineer at the
University of California, San Francisco, who is advising one of the
student teams. "Understanding how to push the size and complexity of
these systems is what is going to have an impact."

Entries in this year's competition come from as far away as Africa and
Japan, and will include a range of strange creations. Some are
practical, such as a biosensor that can detect arsenic concentrations
for use in tainted wells. Others are more whimsical, such as a
bacterial night-light that glows when it gets dark. The oddest
creation, perhaps, is the entry from the University of Freiberg, in
Germany: a microscopic, DNA-based clothing line, christened "Barbie
Nanoatelier" by the team.