WASHINGTON —  It's another step in the quest to create artificial organisms: Scientists have synthesized the complete DNA of a type of bacteria.

The experiment, published online Thursday by the journal Science, isn't a living germ, just its genetic structure.

But scientists from Maryland's J. Craig Venter Institute called it the largest manmade stretch of DNA to date, and therefore a logical step in the fledgling field of "synthetic biology" that aims to build new organisms that work differently than nature intended, such as producing new fuels.

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The Venter group started with some off-the-shelf laboratory-made DNA fragments.

They overlapped and joined these stretches to make ever-larger chunks of genetic material until they finally had a manmade copy of the entire genome of a small bacterium called Mycoplasma genitalium, a genital germ.

Last year, Venter's team performed a "genome transplant": Researchers transplanted all of the genes from one species of Mycoplasma into another, switching a goat germ into a cattle germ.

Somehow, the transplant itself sparked the donor genes to start working; Venter uses a computer analogy to say it "booted up."

Now he must test if this new artificial Mycoplasma genome can boot up, too — by putting the DNA into a living cell to see if takes over and becomes a synthetic organism.

"I don't view that we're creating life," Venter told The Associated Press last year in describing this series of experiments. "I view that we're modifying life to come up with new life forms by designing and synthetically constructing chromosomes."