Deepsea magnetic bacteria offer clues to 3.5 billion-year-old Mars

Additionally, these bacteria play a crucial role in the natural cycling of vital elements like carbon, nitrogen, and phosphorous.

While extensively studied on land and in shallow water, investigating their behavior in deep water poses challenges in collecting them — until now.

In September 2012, a team of researchers, including scientists from the University of Tokyo, embarked on a scientific ocean cruise to explore the southern Mariana Trough in the western Pacific Ocean.

Equipped with a remotely operated underwater vehicle called HYPER-DOLPHIN, the researchers successfully retrieved a remarkable "chimney" from a hydrothermal vent field submerged at 2,787 meters. To put it into perspective, this depth is nearly 4.5 times the height of Tokyo Skytree or over six times that of the Empire State Building in New York.

"We discovered magnetotactic bacteria living on the chimney, which we didn't expect. Due to the chimney's shape, it lacks a clear, vertical chemical gradient which these bacteria typically prefer," the study's co-leader, Associate Professor Yohey Suzuki from the Graduate School of Science at the University of Tokyo, said in a statement.

Inspiring the search for extraterrestrial life

"The bacteria we collected contained mainly 'bullet’-shaped magnetosomes, which we see as a 'primitive' form and so inferred that they have not changed much over many millennia," he added.

"Indeed, the environment we found them in is similar to early Earth about 3.5 billion years ago, when the ancestor of magnetotactic bacteria is estimated to have emerged."

Using a magnet, the researchers collected bacteria from the rim of the chimney. Analyzing the genetic data, they made a surprising discovery: the bacteria were found to be closely related to Nitrospinae bacteria. Nitrospinae are recognized for their significant role in carbon fixation within deep-sea environments. Still, it was previously unknown that they belonged to any magnetotactic groups.

"Deep-sea hydrothermal vents attract attention not only as the birthplace of unique underwater life but also as a potential analogous habitat for extraterrestrial life," said Suzuki.

"The environment where we sampled the bacteria is similar to what we think Mars was like when there was still flowing water on its surface, about 3 billion years ago."

The complete study was published in Frontiers in Microbiology on June 27.