Microbes From the Sea Hold Genetic Surprises

Mar 19, 10:31 PM

Current Headlines: By Gautam Naik

Marine microbes are among the most abundant life form on the planet and among the most mysterious. Now, results from the first phase of a global expedition are expected to provide a glimpse into this long-hidden world while potentially leading to new drugs and even fighting climate change.

Craig Venter, the brash biologist who helped crack the human genome seven years ago, says he and other scientists have used DNA- analysis techniques to discover millions of new genes and thousands of new proteins in ocean microbes. These microscopic life forms are mainly bacteria and organisms known as archaea.

"Everything we've seen is a surprise," Venter said in a phone interview from his marine research vessel, Sorcerer II, in the Sea of Cortez. The unexpected variety of microbial DNA he's found overturns earlier notions that the oceans are a homogenous soup of bacteria and other microscopic life. The details were published on Tuesday in the Public Library of Science Biology, an Internet-based scientific journal.

A diverse supply of microbial DNA from the oceans could be a rich lode for scientists. Drug companies are hunting for new compounds in sea creatures, especially to attack cancer and neurodegenerative diseases. The new data also will allow researchers to compare the DNA of oceanic bacteria to the genetic code of microorganisms that cause human disease.

"This is the largest DNA sequence ever obtained, and the magnitude of what's being done is entirely unparalleled," said Douglas Bartlett, professor of marine microbiology at the University of California, San Diego, who isn't involved in Dr. Venter's project. Marine microbes "have all kind of metabolic activity. It is expected that [Venter's team] will discover new pathways for making drugs and treating infectious disease."

Venter, one of the more savvy scientists when it comes to publicity, likens his project to Charles Darwin's 19th-century voyage on the Beagle. The journey is also modeled on one of the first oceanographic expeditions, by the British sailing ship Challenger in the 1870s, which sought to determine whether there was life in the ocean depths. The findings filled 50 volumes, each as thick as a family Bible. Similarly, the data from the first phase of the Sorcerer expedition is expected to be the largest such trove of genetic information released in the public domain.

The ocean project "is adding new genes to our tool kit," said Venter, 60. "They are key to the next phase of biology: the synthetic phase."

Venter is betting the findings also could pave the way to alternative energy. By adding genes from sea organisms, he speculates, microbes created in the lab may be engineered to release hydrogen, an alternative fuel. Another idea would be for such microbes to absorb excess carbon dioxide and reduce the impact of climate change.

In labs run by the J. Craig Venter Institute in Rockville, Md., one such experiment is already underway: an attempt to alter the process of photosynthesis and produce hydrogen gas. The target is hydrogenase, a small bacterial protein system that produces hydrogen and is also highly sensitive to oxygen. Venter says his team found a hydrogenase by sequencing the genes of microbes fished from the Sargasso Sea, and it is far less sensitive to the presence of oxygen. His team hopes to make a microbe with a synthetic version of that gene and thereby produce hydrogen gas in room air, which is about 21 percent oxygen.

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