Novel evolution machine developed to speed up search for better bugs

July 27th, 2009 - 12:02 pm ICT by ANI  

London, July 27 (ANI): Researchers at Harvard Medical School have developed a new genome engineering machine that tweaks dozens of genes to create billions of unique strains in just a few days-a feat that could speed up search for better bugs.

Unlike the traditional way of tackling one gene at a time to mutate its letters to achieve a particular effect, the new approach, called multiplex automated genome engineering (MAGE), can create hundreds or thousands of mutations in a few days at a cost of a few thousand dollars.

Harris Wang, a researcher at Harvard Medical School, led the project along with colleagues Farren Isaacs and George Church.

“This technique allows us to do some amount of rapid evolution. The general motivation behind what we’re trying to do is develop a set of techniques that will allow us to write into the genome of any organism with the same ease that we are able to read from the genome by DNA sequencing,” New Scientist quoted Wang as saying.

For demonstrating MAGE, the researchers engineered Escherichia coli that churn out five times as much of a chemical called lycopene than their forbearers.

Lycopene is an antioxidant abundant in tomatoes that is related to compounds used to fight cancer and malaria.

With at least 20 genes known to affect lycopene production, conventional genetic engineering techniques that re-write a gene or a part of gene at a time wouldn’t suffice.

In many cases, a mutation in one gene that stymies production can be offset by a mutation in another gene. Sometimes, these double mutants produce a chemical more efficiently than a strain with no changes.

However, instead of trying to directly create double-mutants, the new approach produced hundreds, even thousands of mutations simultaneously, resulting in billions of different strains.

And as lycopene colours cells red, the researchers simply selected the brightest bacteria.

“There might be cells out there that may have these properties, but what we’re trying to do is accelerate this process to find the specific traits we’re interested in,” said Wang.

Isaacs said that engineering vitamin-producing bacteria was not the only use for the new technique.

“It will immediately decrease the time it will take to improve the efficiency and production of virtually any compound that’s generated, right now, in E. coli and looking beyond into other types of organisms as well,” he said.

The researchers said that they are planning to adapt the technique to yeast soon, and plant and animal cells should also prove amenable to MAGE.

Currently, the researchers are teaming up with biofuels and chemical manufacturers in hopes of creating blockbuster strains in the lab that could eventually be used on an industrial scale.

The study has been published in a recent issue of Nature. (ANI)

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