Great intrigue
It is interesting that a large part of these microorganisms are extremophiles. This means that they are able to survive where we cannot. They are fine even at 100 degrees Celsius, they don’t need oxygen, and some like radioactive environments that are disastrous for us. It is this that suggests that they or their components could have come even from outer space. Models show that four billion years ago, temperatures on our planet’s surface and oceans fluctuated between 55 and 80 degrees Celsius. And both water and organic molecules are found in carbonaceous meteorites. It is these meteorites, as it is now believed, that were the main suppliers of water to the Earth, along with comets.
Archaea are found on our planet in hot springs, geysers, salt lakes, oil fields, but can also live in ordinary soil, swamps and our environment. Archaea are particularly abundant in the oceans, and planktonic archaea may be one of the most abundant groups of organisms on the planet. In the oceans, archaea can make up about 20 percent. cells of all microorganisms. Although when talking about the microbial community (microbiota) living inside and on the skin of a person, bacteria are usually thought of, but about 1.2 percent the gut microbiome may consist of archaea that control various life processes. Methanogens – archaea capable of excreting methane live in the human colon, podanten tissues, and vaginal microbiota. There is a growing body of research dedicated to analyzing the human archaeome, the population of archaea that make up the human microbiome and its role in our bodies. So far, no species dangerous to humans have been identified.
The greatest known extremes are Methanopyrus kandleri, which can survive 122 °C (the highest known temperature at which an organism can survive). Picrophilus torridus can grow at an ambient pH of 0 and a temperature of 65 °C. This archaea was isolated from a sulfur-rich volcanic crater in Japan. In 2003, scientists in the Guaymo basin (Gulf of California), 2600 m. discovered at depth the archaea Thermococcus gammatolerans, which not only lives at temperatures of 55-95 °C, but is the most γ-radiation-resistant organism known. It can withstand a dose of up to 30,000 grays (Gy, a unit of measurement of radiation). A person exposed to more than 5 Gy of radiation would die within two weeks.
The search for our first ancestor
We have long wanted to understand what the very first cell on Earth might have looked like, or in other words, the cellular ancestor of all of us. At last, there is hope that this may be possible through the use of comparative genomics.
Comparative genomics is fundamentally very similar to paleontology, comparing animal or human bones found on Earth to find similarities and thus link different life forms. To estimate how far they are from each other in time. When paleontologists study the evolution of vertebrates, for example, they use limb fossils. Places one next to the other according to similarity. This is how geneticists do these days, only they compare the genes of living or long-dead organisms. Comparative genomics is a branch of biological science that studies the origin, evolution, diversity and functions of genetic information. This important data resides in genomes, individual genes or protein structures.
Comparing the genes of the three domains of life: bacteria, archaea and eukaryotes revealed that these individuals descended from a common ancestor because they share genes. Those genes are mainly involved in protein synthesis. For example, they are part of ribosomes. However, the reproductive machinery of bacteria differs from that of archaea and eukaryotes. Archaea and bacteria are always unicellular. Meanwhile, eukaryotic cells are hundreds and even thousands of times larger than prokaryotes. They store more DNA.
Archaic, but useful
Such unique abilities of archaea can be put into practice. There are already industrial products that produce or use archaea. The aforementioned methanogens may not only be an important part of our microbiome. They are the most important link in the production of biogas (biomethane). Archaea can be used to reduce organic compounds in wastewater. They stimulate plant growth and can synthesize new antibiotics. Archaeal proteins have been successfully applied in biotechnology for many years – enzymes that work in high temperatures and organic solvent environments. One of the best-known examples that revolutionized the development of molecular biology methods is Pfu DNA polymerase (from the archaea Pyrococcus furiosus), which is already produced in bioreactors.
Unfortunately, because extremes require extreme conditions to survive, only a few can be grown in laboratories. VU Life Sciences Center scientists are also looking for ways to grow, study and, in the future, apply these unique microorganisms or their enzymes.
Science Festival “Erdvėlaivis Žemė” and the Lithuanian Society of Microbiologists invite you on September 17. together to celebrate the International Day of Microorganisms and to better know the invisible world of microorganisms around us. All events are free, but registration is required mokslofestivalis.eu.
The author of the text is Assoc. Dr. Renata Gudiukaitė
2024-09-03 23:46:34