The research group of Associate Professor Yohei Suzuki of the Graduate School of Science, the University of Tokyo, found that clay minerals that fill the cracks in the basalt that make up the upper part of the oceanic crust are inhabited by microorganisms at extremely high densities (equivalent to the human intestine). I found that.In addition, these microorganisms were found to be heterotrophic organisms that use organic matter as an energy source.
Basalt, which occupies most of the ocean floor, is a rock that has cooled and solidified magma erupted from the Mid-Atlantic Ridge, and its formation has been known for 38 billion years.On the other hand, it is known that the upper part of the crust of Mars is also composed of basalt that erupted from volcanic activity 37 billion years ago.Further analysis of the microbial ecosystem in the upper oceanic crust of the Earth is expected to provide clues to the possible existence of extraterrestrial life on Mars, but it is deep and covered with deposits. It is said that it was difficult to sample the oceanic crust and analyze the microorganisms inside the rock, and the elucidation of the actual situation was delayed.
In this study, the basalt above the oceanic crust formed 329 million years ago and 3350 million years ago by excavating the seafloor in the South Pacific Circumferential Ocean during the 1th Research Voyage of the Integrated Ocean Drilling Program (IODP). Succeeded in collecting the core sample.
Previous studies have identified clay minerals in basalt cracks, which are also known to be the same as those found in large quantities in Martian basalt.This time, we performed elemental imaging to visualize the microbial cells inhabiting clay minerals, which was detected in the previous research, and succeeded in measuring the cell density.
As a result, it was clarified that the cell density of the clay-filled part exceeds 1 billion individuals per 3 cm100, which corresponds to the density of human intestinal microorganisms.DNA analysis also revealed that these microorganisms are heterotrophic organisms that use organic matter as their energy and carbon sources.
It can be said that this result suggests that an ecosystem of fertile heterotrophic organisms exists in the upper part of the oceanic crust, and that a similar ecosystem may exist in the rocks of Mars.
Paper information:[COMMUNICATIONS BIOLOGY] Deep microbial proliferation at the basalt interface in 33.5–104 million-year-old oceanic crust
