Newswise — A groundbreaking discovery has revealed that Magnetotactic bacteria, known for their ability to orient themselves with the Earth's magnetic field, have been found in a previously unexplored location. While these bacteria have been observed on land and in shallow water before, their presence in a hydrothermal vent signifies their remarkable adaptability to survive in the deep ocean. This newfound ability demonstrates their capacity to thrive in environments that are not conventionally conducive to their typical requirements. The study of Magnetotactic bacteria is significant not only for their ecological role on Earth but also for the search for extraterrestrial life. As evidence of their existence can endure in rocks for billions of years, they provide a promising avenue for exploring the possibility of life beyond our planet. Furthermore, the magnetic inclinations of these bacteria can serve as a historical record of magnetic pole shifts over time. This exciting discovery instills hope among researchers that these magnetic bacteria may be found in even more unexpected locations, both on Earth and potentially on celestial bodies like Mars and beyond.
Magnetotactic bacteria possess extraordinary characteristics reminiscent of the superhero Magneto from Marvel Comics. Just like Magneto's uncanny ability to perceive and manipulate magnetic fields, these minuscule organisms possess the capability to "sense" and align themselves with the Earth's magnetic field. Encased within a membrane, these bacteria harbor magnetosomes—iron crystals that arrange themselves in accordance with the Earth's magnetic field, effectively acting as a compass for the bacteria. Consequently, they navigate along the magnetic field lines, either northward or southward, much like trains on a magnetic track. As an integral part of their life cycle, these bacteria play a vital role in the biogeochemical cycling of essential elements such as carbon, nitrogen, phosphorus, and others in the natural environment. While extensive research has been conducted on land and in shallow water, the study of these bacteria in deep water remains relatively limited due to the challenges associated with collection and analysis.
In September 2012, a group of researchers from the University of Tokyo embarked on a scientific expedition to the southern Mariana Trough, located in the western Pacific Ocean. Their objective was to explore the depths of the ocean and study the unique ecosystem around hydrothermal vents. Equipped with a remotely operated underwater vehicle called HYPER-DOLPHIN, they successfully retrieved a hydrothermal vent "chimney" from a depth of 2,787 meters (which is nearly 4.5 times the height of Tokyo Skytree or over 6 times the height of the Empire State Building in New York).
Hydrothermal vents are fascinating geological features formed when seawater seeps into the Earth's crust, where it is superheated by magma, reaching temperatures of up to 400 degrees Celsius. This intense heat causes the water to rise back to the surface, carrying with it minerals and metals. Over time, these deposits accumulate and form chimney-like structures on the ocean floor. These chimneys create a warm and nutrient-rich habitat, hosting a wide variety of unique life forms.
To the researchers' surprise, they discovered magnetotactic bacteria thriving on the chimney. This finding was unexpected because the chimney's shape did not provide the typical vertical chemical gradient that these bacteria usually prefer. Associate Professor Yohey Suzuki from the University of Tokyo's Graduate School of Science explained, "The bacteria we collected had predominantly 'bullet'-shaped magnetosomes, which we consider to be a 'primitive' form. Based on this, we inferred that these bacteria have undergone minimal changes over countless millennia. Interestingly, the environment in which we found them resembles the conditions of early Earth approximately 3.5 billion years ago, when the precursor of magnetotactic bacteria is believed to have emerged."
Using a magnet, the researchers gathered bacteria from the edge of the chimney. Subsequently, they analyzed the genetic information and discovered that these bacteria were closely related to Nitrospinae, a type of bacteria known for their significant role in carbon fixation within deep-sea environments. Surprisingly, these Nitrospinae bacteria had not been previously identified as possessing any magnetotactic properties.
According to Suzuki, one of the team members, deep-sea hydrothermal vents are captivating not only due to their ability to foster unique underwater life but also because they resemble a potential habitat for extraterrestrial organisms. He added, "The environment where we collected the bacteria bears resemblance to the conditions on Mars approximately 3 billion years ago when there existed flowing water on its surface."
Magnetotactic bacteria, also known as magnetofossils, possess magnetic particles in their fossilized remains that can endure in rock formations for billions of years. These magnetofossils offer invaluable insights into ancient geomagnetic history and hold promise in the quest for extraterrestrial life. In 1996, the discovery of iron-crystal fossils resembling bacterial life in the Martian meteorite Allan Hills 84001, estimated to be around 3.6 billion years old, generated significant global excitement. Although the assertion has since faced considerable skepticism, Suzuki remains optimistic about future breakthroughs. Suzuki believes that magnetotactic bacteria can provide vital clues about the early proliferation of bacteria, and there is a possibility of their existence extending beyond Earth, perhaps on Mars or icy moons. The search for these bacteria will persistently explore diverse types and ages of Earth's rocks where their presence was not previously anticipated.
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