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The discovery of solitary little critters deep beneath Earth’s surface has set the world of microbiology on its head while exciting astrobiologists about the possibility of life on other planets. A community of bacteria was found 2.8 kilometers below ground in a goldmine and it lives completely alone and completely independent of any other life forms. It also subsists without sunlight or oxygen. Planetary scientist Chris McKay, of NASA’s Ames Research Center says that the species Candidatus Desulforudis audaxviator is an amazing discovery, and represents the kind or organism that could survive below the surface of Mars or Saturn’s sixth largest moon Enceladus.
Nicknamed “the bold traveler,” the species was found in fluid-filled cracks of the Mponeng goldmine in South Africa. The discovery of the species contradicts the principle that all life on earth is part of one great, interdependent system.
Scientists extracted all of the DNA present within 5,600 liters of fluid from a fracture deep within the mine. Expecting to find a mix of species within the fluid, the researchers were surprised to find that 99.9% of the DNA belonged to one bacterium, a new species. The remaining DNA was contamination from the mine and the laboratory.
A community of a single species is almost unheard of in the microbial world. But this little bacteria has been happily living on its own and seems to have all of the genetic machinery to enable it to survive independently. Since it is the only species in the ecosystem, it must extract everything it needs from an otherwise dead environment.
Analysis by Dylan Chivian of the Lawrence Berkeley National Laboratory showed that D. audaxviator gets its energy from the radioactive decay of uranium in the surrounding rocks. It has genes to extract carbon from dissolved carbon dioxide and other genes to fix nitrogen, which comes from the surrounding rocks. Both carbon and nitrogen are essential building blocks for life as we know it.
D. audaxviator can also protect itself from environmental hazards by forming endospores – tough shells that protect its DNA and RNA from drying out, toxic chemicals and from starvation. It has a flagellum to help it navigate.
Every other species that we know of on Earth planet relies on other species for some benefit. For example, humans rely on plants to photosynthesize so that we can eat them. Also, other known ecosystems on Earth that don’t use sunlight directly, such as lifeforms found in deep sea vents, do use some form of photosynthesis. But this newly found species actually can’t handle oxygen
The water in which D. audaxviator lives has not seen the light of day in over 3 million years, and this could be an indication of how old the species is.
When we start to look for life on other planets, the discovery of this species will help broaden the horizons of our search.
Sources: New Scientist