According to a new analysis carried out by scientists from Montana State Univesity, microbes living in hot sources in the American National Park Yellowstone can explain the evolution of the use of oxygen by organisms.
The lower geyser pool (Lower Geyser Basin) is a thermal complex in which the temperature reaches up to 88 degrees Celsius. It is inhabited by unique mikoorganisms that genetically resemble ancient bacteria or archaeons.
In one of the local thermal pools – Octopus Spring – there is a fairly high level of dissolved oxygen. In the second, called Conch Spring, there is a lot more highly toxic dissolved hydrogen sulfide.
Researchers from Montana State University analyzed these chemical differences to discover the mystery of survival of life before – and during – a great oxidation event [inaczej GOE – Great Oxidation Event – przyp. red.] About 2.5 billion years ago.
Yellowstone National Park – an illustrative photoShutterstock
The evolution of ancient life
The oldest microbes that appeared on Earth were able to use trace amounts of oxygen in their biochemistry. However, the rapid appearance of highly reactive molecular oxygen required them to develop completely new tactics. At high concentrations of hydrogen sulfide, it can block breathing mechanisms in the oxygen organisms we know. That is why scientists were even more interested in how ancient life evolved in hot sources, fighting and using growing oxygen levels.
A team of scientists was managed by a geomicobiologist Bill Inskeep, who has been studying microbes living in the Yellowstone park for almost 30 years.
– Imagine an attempt to create streams of hot water with the right amount of oxygen and hydrogen sulfide. It would be very difficult to recreate this kind of experiment in the laboratory. And it is so cool about studying these environments. We can observe in the exact geochemical conditions that these organisms need for development – said Inskeep.
The team analyzed several samples with microbes from both sources in a genetic angle, thanks to which they could compare their diversity and oxygen activity in both environments.
A greater variety of oxygen microorganisms appeared in Octopus Spring, which must use other microorganisms to survive. They are not able to produce food for themselves, as it happens in other microorganisms. In this pool, life was much more diverse. Almost all microorganisms were active for oxygen breathing.
But even in a poor environment in oxygen and containing hydrogen sulfide, such as Conch Spring, where microorganisms were much less diverse, the potential of the use of oxygen appeared, but hidden.
Hot springs in the Yellowstone American National Park – an illustrative photoAdobe Stock
They don't need large amounts of oxygen
In both sources, various enzymes have been found that neutralize oxygen by adding hydrogen. Interestingly, microorganisms in Conch Spring can produce one, even when there is very few oxygen.
– These enzymes are active at oxygen levels at the nanomolar level [a więc bardzo, bardzo małym – red.]which explains their high production observed in Conch Spring sulfide conditions, “said the Inskeep.
Their results have shown that these genetically ancient, thermophilic microbes breathe at oxygen levels, which are usually considered too low to support such activity and in conditions that are considered too toxic. And since these microorganisms have such skills, it means that they could also have life forms functioning before goee.
At the beginning of the existence of the land, the microbes had to develop in really extreme conditions. However, it turns out that some of them managed to survive and develop even despite very small amounts of oxygen.
Source of the main photo: Adobe Stock