A Taiwanese-led research team has discovered a self-sustaining community of bacteria 2.8km below the surface of the Earth in South Africa, proving that life forms can exist in inorganic environments, academic sources said.
The research team, led by two assistant professors at National Taiwan University (NTU) and composed of several other research fellows of various nationalities, has published its findings in the latest issue of the US-based Nature magazine.
According to the team's research results, the biome, found in a gold mine outside Johannesburg, has possibly been there for 3 million to 25 million years, supporting itself by consuming sulfates and hydrogen, which do not come from a photosynthetic process but from fracture water radiated by uranium.
A species from the division of firmicutes, the largest group in the bacteria community, was found to be able to digest minerals and produce chemical waste which the other kinds of bacteria depend on to live. Researchers said that the firmicutes take the place of photosynthetic organisms and sustain life underground.
The importance of this finding is that it is the first time scientists have proved that life can exist without photosynthesis and be sustained purely on minerals. The results also spell hope that there might be some life forms in the depths of Mars or the moons of other planets.
The project, which has been underway for four years, is a collaboration between Lin Li-hung (林立虹) from NTU's department of geosciences, Wang Pei-ling (王珮玲) at the NTU Institute of Oceanography, Tullis Onstott at Princeton University, Lisa Pratt at Indiana University Bloomington and eight other researchers from the US, Canada, South Africa and Germany.
Taiwan's National Science Council, NASA, the US National Science Foundation and several other institutions have financially supported the project.
Lin, the lead author of the paper, said that they chose the mine in South Africa as the excavation site because the seams there have existed for more than 3 billion years and have experienced very little tectonic activity, which would destroy any subsurface communities.
Lin entered the depths of the mine on 30 occasions during a four-month period, collecting samples from fracture water. The samples were later thoroughly examined for signs of life.
According to the paper, the scientists found various kinds of bacteria in the water, although the population is dominated by a new species, which is related to hydrothermal vent bacteria from the division of firmicutes.