Mysterious microbe plays important role in oce...( An unusual microorganism discovered ...)

An unusual microorganism discovered in the open ocean may force scientists to rethink their understanding of how carbon and nitrogen cycle through ocean ecosystems.

A paper describing the new findings appears in the November 14 issue of the journal Science.

A research team led by Jonathan Zehr, a marine scientist at the University of California, Santa Cruz, characterized the new microbe by analyzing its genetic material, even though researchers have not been able to grow it in the laboratory.

Zehr said the newly described organism seems to be an atypical member of the cyanobacteria, a group of photosynthetic bacteria formerly known as blue-green algae.

"This research has revealed a big surprise about the microbiology of the oceans, and the complex integration of the ocean's nitrogen and carbon cycles," said Philip Taylor, section head in the National Science Foundation (NSF)'s Division of Ocean Sciences, which funded the work.

"The fact that nitrogen fixation in these abundant unicells is decoupled from photosynthesis is intriguing," said Taylor. "This unique adaptation brings up questions about the role of these abundant microbes in the ocean."

Unlike all other known free-living cyanobacteria, this one lacks some of the genes needed to carry out photosynthesis, the process by which plants use light energy to make sugars out of carbon dioxide and water.

The mysterious microbe can do something very important, though: It provides natural fertilizer to the oceans by "fixing" nitrogen from the atmosphere into a form useable by other organisms.

"For it to have such an unusual metabolism is very exciting," Zehr said. "We're trying to understand how something like this can live and grow with so many missing parts."

Earlier research by Zehr's group had revealed surprisingly large numbers of novel nitrogen-fixing cyanobacteria, including the one that is the focus of this study, in th
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