It took more than two years for the scientists to observe how bacteria "eat" stones.

Photo source: napieralski et al. 2020, translated by Jennifer Frazer, proofread by Dong Mengyuan, Guo Xiao, the land under our feet is huge and seems to remain unchanged. However, how the earth was born has always been a mystery.the scientific community has explained this mysterious problem in the dimension of time with the knowledge of Geology and meteorology.rocks form soil through weathering reactions, but this process is difficult to observe for humans.it has long been believed that organisms are involved in this process (life activities are almost everywhere on earth), and scientists have confirmed this possibility in theory.however, no one has ever observed life in the common ferrosilicon continental rocks.after all, the weathering reaction of rocks is too long for a scientist's career.weathered rock nevertheless, a group of scientists from the University of Wisconsin Madison, Bristol University and Pennsylvania State University decided to conduct a 2.5-year experiment to study the viability of microorganisms on such rocks.in order to achieve this, they must come up with ways to speed up the process of rock weathering.one way is to find rocks that are fast weathering.and they did find the basement rock of the Rio Blanco quartz diorite, which is located in the Rio icacos basin, which is weathering abnormally fast.the researchers realized that this might be an ideal study sample for them to complete the experiment within the planned time.the scientists collected pure bedrock samples from a cutting, that is, the soil and the rock beneath it.there is also a transitional zone between these soil and rock areas.here, the fractured bedrock alternates with the new soil.this area has a strange name called "rindlet".the scientists found that in the deepest soil, ATP (a compound produced by cell metabolism) is second only to the surface soil.this also means that there must be some life activities at the bottom of the soil, but what is it? If there is a biological weathering reaction, will electron transfer be involved in this process? An electron is a negatively charged particle that can move around the nucleus. the number of electrons in an atom changes frequently. atoms with more electrons are in the reduced state, while those with fewer electrons are in the oxidation state. all organisms need to acquire electrons to maintain their life activities. They usually obtain electrons from sugars and other organic compounds (i.e. food) in reduced state, and then use these electrons to generate energy in cell respiration. some microorganisms can also use simple inorganic compounds or atoms as electron sources. and organisms that use stone as an electronic source are called chemoautotrophs, which can eat rocks for a living. minerals rich in reduced iron, such as pyrite, biotite and hornblende, are potential food for bacteria. deprived of electrons, these minerals can undergo a chemical decomposition process, i.e. weathering, accompanied by changes in shape. this change should be observed under a microscope. as a result, scientists brought more weathered rock and soil containing microbes back to the laboratory and ground the rock to increase its surface area. then they mixed the rocks with microbes. 30 months later, they put the samples under a microscope. after 864 days of incubation with microorganisms, these rocks appear uneven and pitted, as if corroded by acid. in contrast, rocks in the control group (without microorganisms) retained sharp, smooth edges. bacterial oxidation. Image Source: napieralski et al. 2020 bacterial free control group. Image Source: napieralski et al. 2020, they detected abundant ATP in rock mixtures containing microorganisms, indicating that they were enjoying "food" - that is, these rocks. and another mystery is: who is eating rocks? When they examined the DNA of microbes in the samples, they found that almost all of them were bacteria, but no fungi. the researchers believe that either the amount of "food" in this area is not enough to support the survival of the fungi, or the culture conditions in their experiments cannot support the survival of the fungi originally present in the samples. in addition, they found that these chemoautotrophic bacteria do have a special ability: to take electrons from the external iron atoms. these bacteria take in electrons in a way called extracellular electron transfer. there is another benefit of this approach: these microbes can avoid the accumulation of oxidized iron atoms in the body, thus avoiding a potentially fatal threat. therefore, bacteria can indeed initiate and accelerate the process of rock weathering into soil. the soil on land breeds plants, and plants support almost all other life. link to the original text: the 2020 new tee of all things science is now on sale. Click to read the original text and learn more about it. Click here to accept our content update in time