In the subsoil of the seabed there is a considerable amount of microbes. But the conditions that prevail there, as darkness, high pressure and shortage of nutrients, prevent microorganisms develop their life cycle with the rate at which they would if they were in a more favorable environment.
Knowing the speed of the life cycle of these microbes has an interest that goes beyond the merely academic. These very slow growing bacteria are important within the set of processes affecting the global storage of carbon, including carbon dioxide. 70 percent of our planet is covered by the sea, which means that 70 percent of the planet is made up of seabed sediments stored ancient organic matter. In some places, deposits have more than one hundred meters thick and between ten and thirty percent of the total living biomass on earth is currently in the mud of the seabed. The bacteria on the seafloor convert organic carbon into carbon dioxide (CO2). The speed of their life cycle is therefore essential for the levels of CO2 on the planet.
The team of microbiologist Bente Lomstein at the University of Aarhus in Denmark, noted the extent to which organic carbon metabolism occurs at a much slower pace on the seabed compared to what happens in other known ecosystems. The average generation time of bacterial cells in these ecosystems is very long: one thousand to three thousand years. However, many bacteria have been studied in the laboratory or in nature reproduce within hours.
There is extremely high pressure (which may be of the order of several hundred atmospheres), the total darkness and the lack of nutrients which microorganisms do spend much time in sleep.
The team of Lomstein and Alice Thoft Langerhuus has also analyzed the strategy used by bacteria to survive in such extreme conditions.
Many of these microorganisms are not active, but in the form of endospores, which have a robust shield that protects you from this harsh environment.
The analysis techniques developed for this research may also be useful to explore the average speed of the cycle of life on other ecosystems under harsh conditions, such as communities of microorganisms trapped in the permafrost, which have an extremely low biological activity.
In essence, the permafrost (or permafrost) is ice mixed with mineral and organic particles, and in many areas of the world’s cold regions form a layer that lies underground. There is sufficiently protected from the sun’s rays so that much of the material remains frozen continuously for thousands or even millions of years.