Arsenic anyone?

[Loralee Reach 245]

Arsenic-Eating Bug Holds Clues to Extraterrestrial Life

 

 

Scientists dabbling in the toxic waters of a California lake have found a new species of bacteria that thrives on poisonous arsenic -- a discovery that opens up the likelihood of extraterrestrial life, according to a much anticipated NASA study.

 

Arsenic is a deadly poison to many plants and animals, but the new bacteria slurp it up unscathed and then fold it into their DNA and other crucial components. As long as the bugs have a steady supply of arsenic, they happily live without a chemical that has long been regarded as one of the basic building blocks of all living things.

 

The finding explodes scientists' working definition of the stuff of life -- meaning that life on other worlds might not look exactly the same as life here on Earth.

 

"Maybe there are places elsewhere in our solar system ... where arsenic is more prevalent, and microbes can not only make a living on it but are more composed of it," study co-author Ronald Oremland of the U.S. Geological Survey told AOL News. That "would broaden the possibility of life being out there."

 

The study was published on the journal Science's online site Science Express today after days of speculation about a NASA announcement involving "astrobiology" and "exobiology."

 

The finding "enlarges the probability that life exists elsewhere in the universe," said Louis Irwin, emeritus professor at the University of Texas, El Paso, and author of several books on exobiology, the study of the origins of life and life on other planets. "The value of the current work is to remind us that we need to keep an open mind about what life can look like."

 

Oremland's co-author Felisa .....-Simon, a NASA astrobiology fellow, wondered for years whether there might be microbes somewhere in the vastness of nature that could make a living off arsenic. She and her colleagues decided to take a look in eastern California's Mono Lake, which is heavily laced with arsenic that leaches out of surrounding rocks and is also emitted by the lake's hydrothermal vents.

 

The lake's arsenic level is six times higher than the Environmental Protection Agency's arsenic limit for drinking water. The lake is also extremely salty and alkaline, leading Mark Twain to write after a visit there a century and a half ago that its "venomous water would eat a man's eyes out like fire, and burn him out inside, too."

 

The researchers collected various microbes from the lake, then took them back to the laboratory and subjected the bugs to high levels of arsenic. At the same time, they deprived the bacteria of phosphorus, an element that is supposedly one of the six mandatory nutrients needed by all life forms.

 

To the scientists' surprise, one strain of bacteria did just fine without phosphorus. The new species simply used arsenic in place of phosphorus in DNA, proteins and other molecules. Not only did it survive, but it also grew.

 

It was "an experiment that -- I'll be honest -- shouldn't have worked," .....-Simon told AOL News. When she embarked on the project, "I thought, 'I'm going to ruin my career, because this is crazy.'"

 

.....-Simon, a research fellow without a permanent university position, has jokingly named her new bacterium GFAJ-1. The initials stand for "Give Felisa a Job."

 

.....-Simone doesn't know whether her new microbe relies on arsenic in the wild. But her experiment shows that it can do so, a talent that could be useful if it's surrounded by organisms that can't do the same.

 

"This is about cracking open the door to what evolutionary options on Earth could've been," she said.

[Cato 160314]

This is fascinating, but there's scepticism among some scientists about the reliability of the experiment and the conclusions drawn from it. We'll see how this plays out.