The discovery of magnetobacteria in ocean vents at depths of more than 2,700 meters opens the door to speculation about extraterrestrial life
The ocean floor is a hive of life. In it, species of all kinds coexist in a space characterized by absolute darkness, pressure and cold. In such a hostile place, ocean vents provide a source of heat and food. However, although after reading their description they may seem appetizing, these formations are actually underwater volcanoes that expel water at temperatures above 400 degrees, and the “food” is equally hot minerals. The resulting conditions create unique ecosystems around it, with life specially adapted to each and every one of the different layers that form in the volcano.
Recently, among the organisms that inhabit these underwater oases, a research team from the University of Tokyo has found magnetobacteria. These bacteria have magnetostomes, special organelles that, like small compasses, orient themselves following the Earth’s magnetic field and help the bacterium determine its position. Fossil remains of these organisms found in various parts of the world, along with other minerals, have helped to observe changes in the Earth’s magnetosphere and are believed to help guide the search for life on other planets.
To collect these bacteria, the researchers have used a remote-controlled vehicle called HYPER-DOLPHIN, specially designed to study the seabed. The robot, which is capable of descending to a depth of 4,500 meters, can carry different scientific equipment and perform complex tasks underwater, such as taking samples or images. In this case, to capture the magnetobacteria, they used a special arm with a magnet and placed them in vials so they could be analyzed on the surface.
Once in the laboratory, they carried out a genetic analysis and observed that they were closely related to Nitrospina bacteria. This genus of bacteria obtains its energy from the oxidation of minerals, especially nitrite, which is why they are essential for all marine life. The oxidation of nitrite produces nitrate, which is the main source of nitrogen for marine plants and algae. Therefore, if Nitrospina did not transform nitrite into nitrate, the delicate balance that keeps the oceans alive would be lost. To date, no magnetostome-containing bacteria of this genus are known, but those discovered in chimneys share many common features with them.
The surprising thing about the finding is that the environment is especially hostile for this type of bacteria. Other organisms, called extremophile bacteria and archaea, as well as some more complex life forms have made these conditions their home, but until now it was unknown that magnetobacteria could survive in chimneys. This may help direct current efforts to search for life on other planets.
In the words of Associate Professor Yohey Suzuki of the University of Tokyo School of Science: “Deep-sea hydrothermal vents are attracting attention not only as the birthplace of unique underwater life, but also as a possible analogous habitat for extraterrestrial life. The environment where we sampled bacteria is similar to what we believe Mars was like when water was still flowing across its surface some 3 billion years ago.”
These bacteria have existed on Earth for billions of years, so their fossils are used to study changes in the terrestrial magnetic change, which inverts its positive and negative poles every very long periods of time. The last one on record was 780,000 years ago in the event known as the “Brunhes-Matuyama inversion,” which occurred over a period of several thousand years.
The authors of the article suggest that efforts in the search for life on Mars should focus on areas analogous to terrestrial thermal vents, which once contained liquid water. There, fossils of these organisms could be found with their magnetostomes oriented according to the Martian magnetic field, which is now practically non-existent.
Shinsaku Nakano, Hiroshi Furutani, Shingo Kato, Mariko Kouduka, Toshitsugu Tamazaki and Yohey Suzuki. Bullet-shaped magnetosomes and metagenomic-based magnetosome gene profiles in a deep-sea hydrothermal vent chimney. Front.Microbiol. 14:1174899. doi: 10.3389/fmicb.2023.1174899