Tuesday, October 17, 2006

 

Microbes: Learning to live with oxygen on early Earth

Scientists at the Carnegie Institution and Pennsylvania State University have discovered evidence showing that microbes adapted to living with oxygen 2.72 billion years ago, at least 300 million years before the rise of oxygen in the atmosphere. The finding is the first concrete validation of a long-held hypothesis that oxygen was being produced and consumed by that time and that the transition to an oxygenated atmosphere was long term.

The results are published in the on-line early edition of the Proceedings of the National Academy of Science (PNAS), to appear the week of October 16th.

It is generally believed that before 2.4 billion years ago, Earth's atmosphere was essentially devoid of oxygen. Exactly when and how oxygen-producing photosynthesis evolved and began fueling the atmosphere with the gas that much of life depends on has been hotly debated for some time. Plants, algae, and cyano-bacteria (blue-green algae) emit oxygen as a waste product of photosynthesis - the process by which sugar, essential for nutrition, is made from light, water, and carbon dioxide. [Science, Evolution, Archaea, Ecosystem, Discovery, Botany]

Continued at "Learning to live with oxygen on early Earth"
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Based on "Late Archean rise of aerobic microbial ecosystems" (Abstract)

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