RAS academician, head of RAS Institute of Microbiology Microbial Community Department, G.A. Zavarzin and leading research fellow of the same laboratory T.N. Zhilina (Doctor of Science, Biology) attempted to reconstruct the cradle of life. They came to a conclusion that life could have appeared not in the ocean, but in continental soda lakes, moreover, such lakes can still be found on Earth today.
As a model the scientists have chosen extremely alkaline (pH –9-10) highly mineralized lakes of Eastern-African rift, equatorial lake Magadi, first of all, which is located in the area of recent volcanic activity, and low-mineralized lakes of Central Asia and Baikal Area, located in East Siberian steppes along the Enisey, Selenga and Onon. Only microorganisms can inhabit such lakes, plants cannot grow there and cattle don’t drink their waters, there are almost no pastures around the lakes. Such lakes have conditions quite similar to those of Earth 3 billion years ago. However, for the lake to become a cradle for primordial life, these microorganisms should not only be numerous, but diverse as well? Which means it should include all known systematic groups of microorganisms. All soda lake microbial population has been thoroughly examined. It turned out that number of species in soda lakes is equal to that in ordinary lakes.
These microbial communities are a well-balanced trophic chain: wastes or decay products of certain microorganisms serve as food source for others and the foundation of this food system are photosynthetic cyanobacteria.
However, comfortable conditions for microorganisms are not enough for life initiation. These lakes should host organisms more complex, that microorganisms, otherwise life, once appeared, wouldn’t have a chance for further evolution. There are such organisms: examined soda lakes are inhabited with unicellular algae (some of them are tolerant to soda concentration of 260g/l) and one species of soil algae. The presence of these algae in soda lakes indicates relationship between soda lakes’ microbial population and microbial flora of surrounding soils – that’s the way life appeared on the firm ground.
According to the scientists’ opinion, their results allow considering natural communities of soda lakes to be analogues of terrestrial communities of early Proterozoic era. The scientists also think that these unique models of early life should become microbial reserve parks, because they are worth saving.