Bacteria With Magnetic Field Detection Abilities Discovered in New, Surprising Habitats May Inspire New Search for Life on Mars

A new discovery has revealed that Magnetotactic bacteria, known for their ability to align with the Earth’s magnetic field, can thrive in previously unexplored environments.

While these bacteria have been observed on land and in shallow water, their presence has now been confirmed in the depths of the ocean through the analysis of a hydrothermal vent.

This remarkable adaptation showcases their capacity to survive in unfavorable conditions that deviate from their usual habitat requirements.

The study of Magnetotactic bacteria holds significance not only for understanding their role in Earth’s ecosystem but also for its implications in the quest for extraterrestrial life.

Notably, evidence of their existence can endure within rocks for billions of years, while their magnetic alignment offers insights into the historical shifts of the planet’s magnetic poles.

This groundbreaking discovery instills hope among researchers, suggesting that these magnetic bacteria may be found in unforeseen locations, both on Earth and potentially on celestial bodies such as Mars and beyond.

The abilities of Magnetotactic bacteria seem almost superhuman, reminiscent of the character Magneto from Marvel Comics. They possess an innate ability to “sense” the Earth’s magnetic field, thanks to their possession of magnetosomes—membrane-wrapped iron crystals.

These magnetosomes arrange themselves in alignment with the Earth’s magnetic field, effectively acting as an internal compass for the bacteria. This alignment guides their movement along the Earth’s magnetic field lines, much like trains on a magnetic track, leading them either northward or southward.

As part of their life cycle, they play a crucial role in the biogeochemical cycling of vital elements such as carbon, nitrogen, and phosphorous in nature.

While Magnetotactic bacteria have been extensively studied on land and in shallow water, their investigation in deep water remains challenging due to the difficulties associated with collection.

In September 2012, a group of researchers from the University of Tokyo embarked on a scientific expedition to the southern Mariana Trough in the western Pacific Ocean. Their objective was to explore this region using a remotely operated underwater vehicle called HYPER-DOLPHIN.

During their mission, they successfully retrieved a remarkable geological structure known as a “chimney” from a hydrothermal vent field located approximately 2,787 meters below the ocean surface. To put this depth into perspective, it is nearly 4.5 times the height of the Tokyo Skytree or over 6 times the height of the Empire State Building in New York.

Hydrothermal vents are formed through a fascinating process. Seawater seeps down into the earth’s crust, gradually reaching deeper levels. As it descends, it becomes exposed to the intense heat generated by magma, leading to its superheating at temperatures reaching up to 400 degrees Celsius. Eventually, this heated water rises back to the surface, creating eruptions.

During these eruptions, minerals and metals present in the water are released and deposited into the surrounding ocean, gradually accumulating and forming chimney-like structures. These chimneys provide a warm and nutrient-rich habitat that sustains a diverse array of unique life forms.

“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,” adds Associate Professor Yohey Suzuki from the Graduate School of Science at the University of Tokyo. “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. 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 research team successfully collected bacteria from the periphery of the chimney structure. Subsequently, they conducted a thorough analysis of the genetic data obtained from these bacteria. Surprisingly, the findings revealed that they were closely related to a bacterial group called Nitrospinae. These Nitrospinae bacteria are recognized for their significant involvement in carbon fixation processes within deep-sea environments. However, what made this discovery particularly intriguing was the fact that magnetotactic properties had not previously been associated with Nitrospinae or any related groups of bacteria.

“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,” points out 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 fossilized remnants of magnetic particles found in magnetotactic bacteria, known as magnetofossils, have the remarkable ability to endure within rocks for billions of years. These magnetofossils serve as invaluable resources for researchers, enabling them to unravel the intricate history of Earth’s geomagnetic field. Furthermore, they hold promise as potential indicators in the quest for extraterrestrial life.

One notable incident occurred in 1996 when the Martian meteorite Allan Hills 84001, estimated to be around 3.6 billion years old, sparked global intrigue due to its purported inclusion of iron-crystal fossils resembling bacteria-like life forms.

Although the authenticity of this claim has since been widely debated, there remains a sense of optimism among scientists, including Suzuki, regarding future discoveries.

Suzuki expresses hope that “Magnetotactic bacteria provide clues for the early diversification of bacteria and we hope they will be found beyond Earth, maybe on Mars or icy moons. For now, we will continue to look for more evidence of them in various types and ages of rocks on Earth where they were not previously thought to inhabit.”

Source: 10.3389/fmicb.2023.1174899

Image Credit: 2012, Yohey Suzuki