Mono Lake bacteria: Challenging life adaptability

By Paromita Pain - 07 Dec 2010 9:59:0 GMT
Mono Lake bacteria: Challenging life adaptability

Image © Scott Bufkin

Scientists at the Harvard Smithsonian Centre for Astrophysics may have discovered bacterium that might change the way we view the ability of life forms to adapt forever. In an experiment, bacteria scrapped off the bottom of Mono Lake in California, was grown for months in a laboratory mixture containing Arsenic.

The bacteria gradually replaced the atoms of phosphorous in its body with atoms of Arsenic. Led by Felisa Wolfe-Simon, a NASA astrobiology fellow at the United States Geological Survey in Menlo Park, Calif., this study has clues to living in "a different way" and challenges what “we think are fixed constants of life".

Dr. Wolfe-Simon had said in a conference in 2006, that organism and its coping mechanisms with arsenic could be influenced by the fact that the organism might have incorporated arsenic into its lifestyle instead of phosphorus, especially in already arsenic rich environments. Mono Lake is salty and arsenic heavy and so bacteria was collected from there and fed more Arsenic.

Carbon, Oxygen, Nitrogen, Hydrogen, Sulfur and Phosphorus are the six chemical elements that have always been thought to be essential for life. There has been no substitute for these six basic chemicals. Now the behavior of the bacteria will stimulate, say scientists, other studies on how replacements might be engineered.

While Arsenic shares many chemical properties with Phosphorus, it is this closeness that makes Arsenic poisonous.

Important implications

The results, when confirmed, could have important implications with regard to space missions to Mars and other studies designed to search and study chemical reactions and elements that characterize life on earth. As scientists say the study opens up questions as to whether there are other chemical compositions that could also define life to look out for. This will enable a broader search on what constitutes concepts of living.

While the replacements of the Phosphorus molecules with Arsenic molecules may seem momentous, scientists have shown that the change wasn't easy nor was it a willing exchange. The bacteria were keener to survive and thrived better on the Phosphorous molecules and even till the very end resisted in replacing them.

Dimitar Sasselov, astronomer at the Harvard-Smithsonian Center for Astrophysics and director of an institute on the origins of life there, who was not involved in the study, says while it's true that nature selects and works with set molecules and reactions out many thousand s available, this shows that there might be other options.

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