Scientists devise new way to modify organisms

Scientists have devised a way to modify an organism that was previously impossible to genetically engineer in the lab.

The method, developed by researchers at the J. Craig Venter Institute in Rockville, Maryland, and San Diego, California, could aid the development of biomaterials and biofuels by helping scientists to genetically engineer species that have so far been beyond their reach. It could also aid the Venter institute's project to create synthetic life.

In their paper, published today in Science1, the researchers describe how they removed a genome from the bacterium Mycoplasma mycoides and transplanted it into the yeast Saccharomyces cerevisiae. They were then able to delete a gene from the M. mycoides genome — a feat that would not have been possible in the bacterium, because scientists lack the tools to genetically engineer the organism.

The team then inactivated an enzyme in a related bacterium, called Mycoplasma capricolum, that defends against invading organisms by destroying DNA that has not been tagged with certain chemical modifications, called methyl groups. The team also artificially added methyl tags to the M. mycoides genome to enable the bacterium to get past M. capricolum's defences.

The bioengineers then transplanted the modified M. mycoides genome into M. capricolum, where it was able to direct the M. capricolum cells to form colonies of M. mycoides.

"There are many synthetic-biology applications that need modification of bacteria on a large scale, and yet many organisms that are of interest in this space are not easy to manipulate genetically," says James Collins, a bioengineer at Boston University in Massachusetts, who was not involved with the research. "So this is really quite a nice advance from a genome engineering standpoint."

Last year, the Venter institute reported that it had synthesized the genome of a small bacterium, Mycoplasma genitalium, by stitching together fragments of it in yeast cells. The institute has also transplanted the unmodified genome of M. mycoides into an M. capricolum bacterium.

By: Erika Check Hayden

....... More reading at , A News Release on 20 August 2009

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