the world's smallest ecosystem was discovered in South Africa. Scientists found a very special bacterium, desulforudis audaxviator, 2.8 km (1.7 miles) underground in a mponeng gold mine in South Africa.
Desulforudis audaxviator may be a real "self reliant" microorganism.
It lives 2.8 kilometers underground, completely isolated from the rest of the world. Using the radioactive energy produced by uranium bearing rocks as energy, the bacteria can obtain all the nutrients needed from surrounding rocks and air and complete the metabolic process. They are the only known single species ecosystem in the world. Scientists point out that the bacteria live 2.8 kilometers underground and have no access to sunlight and organic matter traditionally needed to sustain life throughout the year. Most of the time, microbes that live in the deep sea and deep underground are not exposed to sunlight and eat nitrogen compounds. However, the bacteria found this time are totally different - they actually use highly radioactive uranium as their main food. At the same time, the bacteria can also decompose water into hydrogen and oxygen. In this way, they do not need to use sunlight for photosynthesis to get enough energy. For them, radioactive uranium ore and hydrogen constitute the main source of energy. Now experts from Indiana University are working on a more detailed study of the rare bacterium. Scientists speculate that these bacteria may have chosen a completely different evolutionary path, so that they do not need to rely on the external environment. Preliminary analysis suggests that this unique bacterium is similar to the thermophilic bacteria that scientists have known for a long time, and may be the oldest living thing on earth - it has been around for nearly 3.25 billion years.