Death of methane producing microbes gave us oxygen and life

April 9th, 2009 - 11:45 am ICT by IANS  

Sydney, April 9 (IANS) The death of methane-producing microbes, among the earth’s earliest life forms, gave us oxygen and life in all its complexity, according to a new study.
Because they produced methane, a gas which reacts with oxygen, these early microbes prevented the earth’s early atmosphere from being oxygenated, said the study’s co-author Mark Barley, professor at University of Western Australia’s (UWA) School of Earth and Environment.

Only when the planet began to cool - resulting in a reduction of nickel in the oceans - were oxygen producing photosynthetic bacteria able to thrive.

“The nickel crash after its early boom 2.7 billion years ago helped make our planet habitable by complex life,” Barley said. “Methane-producing microbes (methanogens) require the element nickel for their life and for the formation of methane.”

“Prior to 2.7 billion years ago, the global oceans were very nickel-rich and would have supported a huge methanogen population resulting in a methane-rich atmosphere. When oceanic nickel contents declined after this time this would have caused a famine for methanogens and significantly reduced the methane content of the atmosphere.”

Barley and his international team of geobiologists, along with lead researcher Kurt Konhauser, studied the nickel content of banded iron formations - rocks which preserve a history of the state of the oceans over millennia.

By modelling the nickel content of the ancient oceans, they posited that the cooling of the earth’s interior and reduction of oceanic nickel content caused a major drop in methane production.

This may have helped photosynthetic bacteria to evolve or helped them become a dominant microbial population necessary for the oxidation of the atmosphere, said an UWA release.

These findings were published in the Thursday edition of Nature.

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