After 12 years of painstaking work, scientists have finally learned how to reproduce one of the most mysterious species of microorganisms on Earth.
When scientists analyzed the DNA of biomaterials taken from the bottom of the Arctic Ocean back in 2010, they found something amazing. A previously unknown organism belonging to the archaea - a domain of unusual microorganisms - was found to have signs linking it to a completely different domain, eukaryotes.
The researchers named their find Lokiarchaeota, after the Loki's Castle hydrothermal vent near Greenland, where it was found. For almost ten years they racked their brains over whether they really managed to discover something unique, or whether it was just biological "dirt" that distorted the overall picture. However, now all doubts are over: for the first time in history, scientists have managed to grow Lokiarchaeota in laboratory conditions.
In practice, this means that now microbiologists have a unique chance to conduct many necessary experiments that will help us look far into the past and find the very first living things that inhabited the young Earth. The research results are published in the journal Nature.
The tree of life is divided into three main branches. One of them is occupied by bacteria - unicellular microbes that do not have a nucleus and membrane-bound organelles. They move through undulating structures called flagella. Another branch is eukaryotes, organisms whose cells contain nuclei and membranes. These include people, animals, plants, and algae.
And then there are archaea. They are very similar to bacteria in the sense that they lack nuclei and membrane-bound organelles, and they also use flagella. However, there are several key differences. Archaea are divided according to a completely different principle. Their cell walls are made from a different material. Their RNA is quite different from the RNA of bacteria. All these features make it possible to distinguish archaea into an independent branch.
However, Lokiarchaeota breaks down this system, presenting itself as a hybrid of archaea and eukaryotes. And she is not alone: researchers have also discovered relatives of this amazing microbe, also named after the gods of the Scandinavian pantheon: Thorarchaeota, Odinarchaeota and Heimdallarchaeota. Together they are called the "Asgardian Archaeans". There is an assumption that they can be the sources of all eukaryotic life on Earth. Scientists believe she was born when the Asgardian consumed a bacterium, thus creating a new type of microorganism.
Ordinary bacteria, placed in a nutrient medium, double their numbers in just half an hour. It took Lokiarchaeota a full 20 days. Neither the change in the substrate nor a number of other side measures were able to speed up the process. The result of their painstaking work, which took 12 years, scientists named Prometheoarchaeum syntrophicum after the famous titan Prometheus.
Curiously, Prometheus will only multiply in the presence of one or two other microorganisms: the archaea Methanogenium and the bacteria Halodesulfovibrio. When Prometheoarchaeum breaks down amino acids into food, it produces hydrogen, which other microbes happily absorb. If this does not happen, then the excess of hydrogen in the medium slows down the already not the fastest growth. This makes bacteria true symbionts, and the type of symbiosis in this case is syntrophic: the growth and reproduction of one species depends on what the other eats.
In addition, the archaean-from-the-test tube revealed long tentacles, inside which the symbiont microbes found refuge for themselves. Scientists suggested that when the concentration of oxygen on Earth began to increase, this organism entered into symbiosis with bacteria that actively use oxygen - thereby the chances of survival for both increased dramatically.