In addition to the life on the surface of the Earth and in its oceans, ecosystems have evolved deep under the earth coined by the term “deep biosphere” which stretches several kilometers down into the bedrock. The conditions are harsh without oxygen and other favorable conditions present in the earth surface. The knowledge about ancient life in this deep environment is extremely scarce and most studies so far have focused on the prokaryotes. A new study by an international team of researchers led by Dr. Henrik Drake of the Linnaeus University and Dr. Magnus Ivarsson of the Swedish Museum of Natural History sheds light on eukaryotes in this deep setting. They present the first in situ finding of fungi at great depth in the bedrock. This ancient life is found at 740 m below the ground surface. It represents a new piece in the deep biosphere puzzle.

       Henrik Drake, lead author of the study discovered the fungi in a cavity hidden within a vein in a drill core he was examining. They were beautiful like mineral crystals and abundant in mycelium of fungal hyphae. To him it was like observing a small community frozen in time.

       Magnus Ivarsson another author explained more about the fungi. Their detailed synchrotron-based investigations clearly proved that it is fungi adapted to anaerobic conditions. The fungi are partly mineralized and partly organically preserved, which a rare find is revealing how organisms in that environment are fossilized and preserved.

       High spatial resolution isotope analysis within the minerals that occur along with the fungi revealed that a variety of microbial processes had occurred in the caveat, including methane consumption and sulfate reduction. The fungi could not be dated precisely but there are proxies pointing to an age of tens of millions of years.

       The study confirms a previously hypothesized consortium between fungi and sulfate reducing bacteria, a coupling that has yet been unsupported by direct evidence in nature. As fungi provide hydrogen gas that fuel prokaryotes, the findings suggest a re-evaluation of the energy cycling within the energy-poor deep continental biosphere. Eukaryotes have been neglected in the deep biosphere research. This new finding proposes that they may be key players in this globally vast realm. Studies of subterranean life-forms have implications for early life on our planet and for life on other planets, where hostile conditions may have inhibited colonization of the surface.

Source: www.sciencedaily.com