Hot Spring 'Buddhas'

The Three Buddhas are hot springs in Nevada that house archaea, microorganisms that can live in extremely hot, acidic, or salty conditions.

Evidence now points to the fact that the low-temperature archaea might have evolved from a moderate-temperature environment and not from their high-temperature cousins.

Archaea, first spotted in the 1970's, have intrigued scientists for their ability to survive in extreme conditions where no other organism can.

Since the 1990's, scientists discovered that these little guys could also live in low-temperature environments such as oceans and lakes.

"Archaea represent one of the three domains of life on Earth," said study author Chuanlun Zhang, an associate professor of marine sciences at University of Georgia. "Understanding their evolution may shed light on how all life forms evolve and interact with the environment through geological history."

Zhang and his colleagues examined a common group of archaea known as Crenarchaeota whose low-temperature success are most likely attributed to a unique molecule known as crenarchaeol that allows the organism's cell membrane to remain flexible in cooler environments.

Originally, it was believed that crenarchaeol is a new evolutionary feature and evolved 112 million years ago during the Cretaceous period, the same time that dinosaurs became extinct.

But by looking at samples from springs in California, Nevada, and Thailand, Zhang's study found that crenarchaeol was mostly found at temperatures of about 104 degrees Fahrenheit, well above even the warmest sea surface temperatures during the Cretaceous period.

This led them to conclude that the crenarchaeol, and by extension the groups of Crenarchaeota that have the molecule, evolved much earlier than previously thought about 3.5 billion years ago, shortly after life began to emerge on Earth.

Understanding these ancient organisms is important to the planet's future, Zhang said Most scientists believe that Crenarchaeota play an important role in fixing carbon dioxide, helping sequester the greenhouse gases from the atmosphere. Having a better understanding of how abundant Crenarchaeota are and how much carbon they remove can help scientists more accurately model the effects of global warming.

--Sara Goudarzi

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Credit: University of Georgia