[Editors] MIT enlists microbes to solve global problems

[Elizabeth Thomson]

http://web.mit.edu/newsoffice/2009/bacteria-energy-0217.html


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Enlisting microbes to solve global problems
--MIT teams harness bacteria to produce energy, clean up environment
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For Immediate Release
WEDNESDAY, FEB. 18, 2009

Contact: Elizabeth A. Thomson, MIT News Office
E: thomson at mit.edu, T: 617-258-5402

Photo and Graphic Available

CAMBRIDGE, Mass.--In the search for answers to the planet’s biggest  
challenges, some MIT researchers are turning to its tiniest organisms:  
bacteria.

The idea of exploiting microbial products is not new: Humans have long  
enlisted bacteria and yeast to make bread, wine and cheese, and more  
recently discovered antibiotics that help fight disease. Now,  
researchers in the growing field of metabolic engineering are trying  
to manipulate bacteria’s unique abilities to help generate energy and  
clean up Earth’s atmosphere.

MIT chemical engineer Kristala Jones Prather sees bacteria as diverse  
and complex “chemical factories” that can potentially build better  
biofuels as well as biodegradable plastics and textiles.

“We’re trying to ask what kinds of things should we be trying to make,  
and looking for potential routes in nature to make them,” says  
Prather, the Joseph R. Mares (1924) Assistant Professor of Chemical  
Engineering.

She and Gregory Stephanopoulos, the W.H. Dow Professor of Chemical  
Engineering at MIT, are trying to create bacteria that make biofuels  
and other compounds more efficiently, while chemistry professor  
Catherine Drennan hopes bacteria can one day help soak up pollutants  
such as carbon monoxide and carbon dioxide from the Earth’s atmosphere.

‘Chemical factories’

Found in nearly every habitat on Earth, bacteria are chemical  
powerhouses. Some synthesize compounds useful to humans, such as  
biofuels, plastics and drugs, while others break down atmospheric  
pollutants. Most rely on carbon compounds as an energy source, but  
species differ widely in their exact metabolic processes.

Metabolic engineers are learning to take advantage of those processes,  
and one area of intense focus is biofuel production. At MIT, Prather  
is developing bacteria that can manufacture fuels such as butanol and  
pentanol from agricultural byproducts, and Stephanopoulos is trying to  
make better microbial producers of biofuels by improving their  
tolerance to the toxicity of the feedstocks they ferment and products  
they make.

The recent spike in oil prices and growing greenhouse-gas emissions  
have catalyzed the push to find better pathways to produce biofuels  
and other chemicals such as bioplastics. “You see a visible boost when  
you have a crisis linked to energy problems,” says Stephanopoulos.

Manufacturing plastics and textiles using bacteria can be far less  
energy-intensive than traditional industrial processes, because most  
industrial chemical reactions require high temperatures and pressures  
(which require a great deal of energy to create). Bacteria, on the  
other hand, normally thrive around 30 degrees Celsius and at  
atmospheric pressure.

Metabolic engineering involves not only creating new products but also  
developing more efficient ways of making existing compounds. Recently,  
Prather’s laboratory reported a new way to synthesize glucaric acid, a  
compound with multiple uses ranging from the synthesis of nylons to  
water treatment, by combining genes from plants, yeast and bacteria.

Prather is also working on bacteria that transform glucose and other  
simple starting materials into compounds that can be used to make  
biodegradable plastics such as PHA (polyhydroxyalkanoate). In  
Stephanopoulos’ laboratory, researchers are developing new ways to  
produce biodiesel, plus other compounds including the amino acid  
tyrosine, a building block for drugs and food additives; biopolymers  
and hyaluronic acid, a natural joint lubricant that can be used to  
treat arthritis.

Both labs collaborate in a project to engineer the isoprenoid pathway  
in yeast and bacteria, which is responsible for the biosynthesis of  
many important pharmaceutical compounds. The two labs are  
investigating methods to make different compounds with higher activity  
as well as improving productivity.

Microbes express a huge range of metabolic pathways, offering great  
opportunities but also challenges. “Biology has a lot of diversity  
that’s untapped and undiscovered, but the flip side is that it’s hard  
to engineer in precise ways,” says Prather. “Nature has evolved to do  
what it does, and to get it to do something different is a nontrivial  
task.”

Bacterial cleanup crew

Drennan is also looking to bacteria, but with a different goal in  
mind. Instead of using bacteria to build things, she’s studying how  
they break things down — specifically, carbon dioxide, carbon monoxide  
and other atmospheric pollutants.

Her microbes, found in a range of habitats including freshwater hot  
springs, absorb carbon dioxide and/or carbon monoxide and use them to  
produce energy. Such microbes remove an estimated one billion tons of  
carbon monoxide from Earth and its lower atmosphere every year.

“These bacteria are responsible for removing a lot of CO and CO2 from  
the environment,” says Drennan, who is a Howard Hughes Medical  
Institute investigator. “Can we use this chemistry to do the same  
thing?”

To answer that question, Drennan and her students are using X-ray  
crystallography to decipher the structures of the metal-protein  
enzymes involved in the reactions, which they believe will allow them  
to figure out how the enzymes work. That understanding could lead to  
development of catalysts to lower carbon monoxide levels in heavily  
polluted areas.

“If you’re going to borrow ideas from nature, the first step is to  
understand how nature works,” she says.


Written by Anne Trafton, MIT News Office
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