Unique microbes discovered in extreme environment
Washington: A new DNA analysis of rocky soils in the martian-like landscape on some volcanoes in South America has revealed a handful of bacteria, fungi, and other rudimentary organisms, called archaea, which seem to have a different way of converting energy as compared to their counterparts elsewhere in the world.
“We haven’t formally identified or characterized the species but these are very different than anything else that has been cultured. Genetically, they’re at least 5 percent different than anything else in the [DNA] database of 2.5 million sequences,” Ryan Lynch, a microbiologist with the University of Colorado in Boulder who is one of the finders of the organisms, said.
The database represents a close-to comprehensive collection of microbes, he added, and researchers worldwide add to it as they publish papers about the organisms.
The soil samples collected by Lynch’s co-author, University of Colorado microbiologist Steven Schmidt, from the dry slopes of the tallest volcanoes in the Atacama region provide hardly any support to life.
Much of the sparse snow that falls on the terrain sublimates back to the atmosphere soon after it hits the ground, and the soil is so depleted of nutrients that nitrogen levels in the scientists’ samples were below detection limits.
Ultraviolet radiation in this high-altitude environment can be twice as intense as in a low-elevation desert. And, while the researchers were on site, temperatures dropped to -10 degrees Celsius (14 degrees Fahrenheit) one night, and spiked to 56 degrees C (133 degrees F) the next day.
How the newfound organisms survive under such circumstances remains a mystery.
Although Lynch, Schmidt, and their colleagues looked for genes known to be involved in photosynthesis, and peered into the cells using fluorescent techniques to look for chlorophyll, the scientists couldn’t find any evidence that the microbes were photosynthetic.
Instead, they think the microbes might slowly convert energy by means of chemical reactions that extract energy and carbon from wisps of gases such as carbon monoxide and dimethyl sulfide that blow into the desolate mountain area.
The process wouldn’t give the bugs a high energy yield, Lynch said, but it could be enough as it adds up over time.
While normal soil has thousands of microbial species represented in just a gram of soil, and garden soils even more, remarkably few species have made their home in the barren Atacama mountain soil, the new research suggests.
“To find a community dominated by less than 20 [species] – that’s pretty amazing for a soil microbiologist,” Schmidt said.
Studying the microbes and finding out how they can live at such an extreme can help set boundaries for life on Earth, Schmidt said, and tells scientists what life can stand.
There’s a possibility that some of the extremophiles might utilize completely new forms of metabolism, whereby they convert energy in a novel way.
A scientific article about the new findings has been accepted for publication by the Journal of Geophysical Research-Biogeosciences.