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Gene swap experiment makes altering bugs easier

WASHINGTON - Researchers seeking ways to genetically-modify microbes to get them to do their bidding said on Thursday they had taken a big step toward their goal by transplanting an altered genome from one germ to another.

They hope the experiment will help scientists alter bacteria to make new vaccines, clean up toxic waste and design new antibiotics. They also hope they can use the technique to try to create entirely synthetic microbes.

Carole Lartigue and colleagues at the J. Craig Venter Institute in Maryland took the entire genome out of one type of bacteria, inserted it into yeast, genetically engineered it, and then transplanted the altered gene map into another species of bacteria.

Writing in the journal Science, they said their method might be used to tinker with the genetics of a range of bacteria that have been difficult to engineer.

“Many medically or industrially important microbes are difficult to manipulate genetically,” they wrote.

“This has severely limited our understanding of pathogenesis and our ability to exploit the knowledge of microbial biology on a practical level. We hope that the cycle presented here can be applied to other species, to help solve these problems.”

Lartigue, who is now at the Biotechnology Industry Organization, said there may be a direct application for animal vaccines. The Mycoplasma mycoides bacterium they used causes a disease called pleuropneumonia in cattle and goats.

“There is an urgent need for vaccines,” they wrote. “This technology could accelerate the construction of live vaccine strains.”

Venter, named as an author in the paper and who founded the institute, is working to make genetically manipulated or completely synthetic organisms.

Last month, Exxon Mobil Corp signed a $600 million deal with Venter’s privately held Synthetic Genomics Inc to work on making biofuel from algae.

Venter has said he hopes to manipulate organisms to produce biofuels, clean up toxic waste and sequester carbon to slow global warming. Researchers already regularly engineer life forms by adding or deleting genes.

Lartigue’s team started with a simple species of bacteria called M. mycoides. It does not have cell walls and is difficult to fight using antibiotics.

They removed its genome and inserted it into yeast — an organism that is distant from bacteria on the tree of life. Yeast is easier to manipulate in the lab and this process allowed the team to alter the genes — in this case, deleting one gene not necessary for bacteria to live.

Then they transplanted this genome into another species of bacteria, M. capricolum. The new organism began replicating and after a few divisions it produced a new strain of M. mycoides.