In recent decades, new, more powerful and cheaper sequencing techniques have made it possible to trace genetic material in places where it had not been possible to do so until now. Thanks to this, it has been discovered that microbial life, made up of viruses, bacteria, fungi and others, is very abundant and is present even in the most inhospitable places.
Even underground. It is known that there organisms living underground, in the pores and cracks through which water seeps and even within the rocks themselves. Now a study published in «Communications Biology» has made an even more surprising find.
Scientists from the University of Tokyo (Japan), have found an oasis of life, in which dense communities of microorganisms live inside volcanic rocks buried 100 meters below the ocean floor. The most surprising thing is that there are as many microbes there as in the human intestine, hovering in numbers of up to 10,000 million cells per cubic centimeter.
The finding implies that life could exist in places as difficult as these not only on Earth, but also beyond, such as on Mars or on distant planets.
“Right now I am more convinced that we can find life on Mars»he said in a statement Yohey Suzukifirst author of the work. “If this were not the case, it would have to be because life depends on other processes that are not present on Mars, such as plate tectonics”.
This process is responsible for changing the appearance of the earth’s surface through the movements of tectonic plates, huge continental blocks that, when sliding, generate earthquakes or volcanism zones.
One hundred thousand cells per cubic centimeter
Suzuki’s team did their analyzes on basalt rock samples from 33 to up to 104 million years old. There they found the presence of microorganisms congregated around veins of iron-rich clay.
Its concentration is important and is around 10,000 million cells per cubic centimeter, a million times more than what is found in more recent basalts, not yet so colonized, and around a hundred million times less than what could be found in one cubic centimeter of ocean sediment floor.
The authors have suggested that these dense communities live on the iron-bound organic matter of the clay veins, because they have observed that in the oldest basalts most of the bacteria are relatives of microorganisms that live on such sources.
How are these oases of life formed?
These oases of life have spectacular origins. Submarine volcanoes expel lava at temperatures of up to 1,200 ºC, which solidifies in the form of rocks when it comes into contact with water.
This rapid cooling causes fractureswhich are normally less than a millimeter thick and, over millions of years, these gaps are filled with clay minerals, laying the foundation for what eventually becomes a garden for microorganisms.
«These cracks are a very friendly place for life»Suzuki said. “Clay minerals are like a magical material on Earth; if you can find them, you can almost always find microorganisms living on them».
All of this is more interesting than it sounds, because underwater eruptions have been occurring for the last 3.8 billion years, while bacteria and other microorganisms have been living on inorganic sources of energy for 3.8 to 3.5 billion years.
However, most of the planet’s oceanic crust is less than 10 million years old, making life in older basalt rocks is poorly understood.
From the bottom of the ocean to Mars
In addition, Suzuki believes that the minerals that fill the gaps in the rocks are similar to those that might now be on the surface of Mars.
«The minerals are like a fingerprint of the conditions that existed when the clays were formed»said the researcher. «With a pH between neutral and slightly alkaline, low temperature, moderate salinity, medium rich in iron and basalt rock», has listed. «All of these conditions are shared by the deep ocean and the surface of Mars.».
For this reason, Suzuki is collaborating with NASA to outline a plan with which to analyze rock samples full of clay minerals on the surface of the red planet, in the next robotic missions.
On this occasion, the rock samples were collected in 2010, during an expedition of the mission “Integrated Ocean Drilling Program” (IODP), at three points around Auckland Island, New Zealand.
The researchers used 5.7-kilometre-long metal cores to reach the ocean floor, then dug down to a depth of 125 meters to obtain cylinders of soil about six centimeters wide. The first 75 meters turned out to be sediment, so they sampled about 40 meters of volcanic rock.
Font: GLS / ABC
Reference article: https://www.abc.es/ciencia/abci-oasis-vida-lugar-mas-insospechado-dentro-rocas-volcanicas-bajo-mar-202004022038_noticia.html
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