Md. Team Finds Species of Sea Microbes
A Maryland research team that helped decipher the human genome has applied its powerful DNA analyzers to the high seas, discovering in a few giant gulps of seawater at least 1,800 new species of marine microbes and more than a million genes previously unknown to science.
The treasure trove of novel life-forms adds significantly to scientists’ appreciation of the oceans’ astonishing biodiversity. It could also deepen their understanding of key biological, chemical and climatic cycles, which are regulated in large part by ocean microbes.
Moreover, many of the newfound genes inside those microbes appear capable of performing chemical reactions that no scientist has ever achieved in a laboratory. That suggests the microbes could be put to work cleaning up polluted sites, synthesizing new drugs and producing free hydrogen as an energy source.
Indeed, much of the work was funded by the Department of Energy as part of a program that aims to harness the microbial world — an enormous but largely unexplored fraction of all life on Earth — to help solve the world’s energy and environmental problems.
“I’ve been swimming and sailing for years,” said lead researcher J. Craig Venter, “and it blows my mind that each mouthful of seawater I’ve swallowed has had tens of millions of bacteria and hundreds of millions of viruses that science has never seen before.”
Venter gained fame in the late 1990s for leading the upstart company that ultimately came in neck-and-neck with federally funded researchers in the race to sequence the human genome. Now he is president of the Institute for Biological Energy Alternatives, a nonprofit science research institution in Rockville that is looking for biological and genetic ways to reduce climate-changing greenhouse gas emissions.
Combining his two loves, sailing and science, Venter took a research team to Bermuda to test an idea. Scientists have long suspected that the oceans are full of bacteria and other microbes that, because they are not easily grown in laboratory dishes, have proven frustratingly difficult to identify or study.
Why not capture those microscopic organisms by sucking seawater through a series of filters, Venter thought, then subject the filters and their minuscule “catch of the day” to the same kind of DNA analysis that helped him determine the exact spelling of the human genetic code?
In effect, the strands of DNA would amount to detectable footprints confirming the existence of each species. And by comparing their finds to gene sequences from other, better studied microbial species, the team would be able to figure out — at least roughly — the biological functions of the newly discovered genes.
The approach was radical. Venter’s DNA analysis system works by cutting up all the genetic material it finds into little pieces, “reading” each piece’s code, and then stitching them back together — virtually — in a computer. It is tricky enough to put those pieces in the right order when all the DNA is from a single organism, such as from a person or a fruit fly. But when the sample consists of DNA from thousands or millions of organisms, it takes an enormous amount of computing power and highly reliable mathematical formulas to make sure DNA pieces from different species are not combined by mistake — an error that would throw off any final count of how many different species were there.
To simplify the task, Venter chose as his testing ground the Sargasso Sea — a large, nutrient-poor part of the North Atlantic surrounding Bermuda that has long been presumed to be relatively devoid of microbial life.
That was the first myth the work overturned.
“It turned out to be just the opposite,” Venter said.
Water drawn from six research sites in the sea contained DNA that comes from a minimum of 1,800 previously unidentified species , and perhaps as many as 53,000 species, of bacteria, his team reports in Thursday’s online issue of the journal Science.
“This just dwarfs anything like it ever done before,” said Jo Handelsman, a University of Wisconsin expert in microbial diversity. “It just shows that biodiveristy is larger than we can get our hands around, even greater than we can guess.”
The analysis also specifically identified 1,214,207 genes — bits of DNA that perform a specific function. That is at least twice as many genes as have been characterized to date from all sources.
Some of the new genes give a clue as to how the nutrient-poor Sargasso can be home to so much life: The team found nearly 800 new so-called photoreceptor genes, which allow organisms to use energy from sunlight. Apparently under pressure of food shortages, microbes in the Sargasso evolved many new ways of getting energy from light.
That could give chemists many new ideas about how to harness solar power. Similarly, Venter noted, the work identifies about 50,000 new genes that appear to specialize in freeing hydrogen atoms from other compounds — a basic chemical reaction that, if harnessed or mimicked in a synthetic system, could help launch the much ballyhooed but still unattained hydrogen economy.
Still other genes appear capable of chemically altering heavy metals, suggesting they could teach scientists a thing or two about detoxifying contaminated sites.
“It’s a phenomenal job,” said Ed DeLong, a scientist at the Monterey Bay Aquarium Research Institute in California. “What we have here is a parts list of the dominant players in this marine community. And since we didn’t know much about the parts, much less what they’re doing, it’s very exciting.”
Reported By TechNews.com, http://www.TechNews.com
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