( Scientists at Oregon State University h...)Odd energy mechanism in bacteria analyzed

The microorganism is SAR11, the smallest free living cell known and probably the most abundant organism in the seas. By being able for the first time to study the SAR11 "proteorhodopsin" gene in a laboratory, researchers will be able to better understand how it is activated, its role in the life and survival of SAR11, and how it affects ocean ecology.The findings are being published today in the journal Nature.

Surprisingly, the SAR11 bacteria continued to grow normally whether or not there was light available - indicating to OSU researchers that the cell does not require this energy producing mechanism in normal conditions. It's possible, they said, that this alternate form of photochemistry serves as a "backup" system to provide energy to the cells when they face starvation in the open ocean, which often has very limited nutrients.

"It's exciting to learn more about another form of photochemistry that does not use chlorophyll", said Stephen Giovannoni, a professor of microbiology at OSU. "This proteorhodopsin gene, however, seems to have a subtle role in the life and survival of SAR11, and appears to be an auxiliary system to aid cell survival."

The level of interest in SAR11 is high, researchers say, because it dominates microbial life in the oceans, survives where most other cells would die, and plays a major role in the cycling of carbon on Earth. These bacteria may have been thriving for a billion years or more, but they have the smallest genetic structure of any independent cell and were only first discovered by OSU scientists in 1990.

Although tiny, because of their huge numbers SAR11 plays a major role in the planet's carbon cycle as a consumer of organic carbon. Its main energy generat
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Source:Oregon State University