Hungry bacteria may have made Earth hospitable to life 2.5 billion years ago

January 22nd, 2009 - 5:07 pm ICT by ANI  

London, Jan 22 (ANI): A new analysis has led scientists to determine that hungry nickel-grabbing bacteria could have caused the surge in atmospheric oxygen 2.5 billion years ago that made Earth hospitable to life.

According to a report in New Scientist, the analysis was done by Stefan Lalonde of the University of Alberta in Edmonton, Canada, and colleagues, who measured the concentration of nickel deposited in layered sedimentary rocks, or banded iron formations.

They found that levels had dropped by two-thirds in the 200 million years prior to the Great Oxygenation Event.

The team speculate that this drop in nickel starved primordial ocean-dwelling bacteria called methanogens that used dissolved nickel in seawater to help turn food into energy and methane.

As methane reacts with oxygen to remove it from the atmosphere, a decline in the methane produced by bacteria would have led to a build-up of oxygen.

Though it is not clear quite how much the ancient bacteria relied on the metal, growing modern methanogens in the lab requires extremely high concentrations of nickel, said Stephen Zinder at Cornell University in Ithaca, New York.

According to the researchers, the nickel shortage could have caused by a surge in the number of magma plumes just before the nickel decline removed a large amount of heat from Earths core.

In these cooler conditions, more oceanic crust was created relative to continental crust. This contains less of the nickel that the bacteria can use.

This study is one of the first to look at hard data about metal concentrations, which is an important new idea, said Timothy Lyons of the University of California, Riverside. (ANI)

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