Japanese researchers have shown that aerobic microorganisms from sediment from the South Pacific ocean is able to feed and multiply, even after lying in the clay for tens of meters below the bottom 101 million years, reported in Nature Communications. For example, these bacteria can be studied evolutionary processes, characteristic for bacteria with an extremely slow metabolism, and the limits of life on Earth.
In the sediments at the bottom of the seas and oceans is inhabited by a variety of bacteria: they make 12-45 percent of the total mass of microorganisms and about 0.6–2% of the biomass of all living beings on the planet. Apparently, the microorganisms that live in the bottom sediments can settle for very small amounts of they need for life substances. Tracks aerobic (needing oxygen) bacteria are found even in the clay in the cracks of volcanic rocks composing the bottom of the South Pacific gyre. Samples (cores), Japanese researchers pulled from the depths of 51, 109,6, and 121,8 metres below the seabed. However, the work did not study the metabolism of the bacteria found.
Now, some of the authors previous work, in particular Morono Yuki (Yuki Morono) and his colleagues from the Japan Agency for science and technology for marine mineral resources (JAMSTEC) and the Rhode Island University, presented the results of cultivation of microorganisms, which they found in cores raised from a depth of 74.5 feet below the bottom (3700-5700 meters below sea level). Bacteria were revealed by staining with fluorescent dye SYBR Green I, which binds to DNA molecules and sequencing of 16S ribosomal RNA.
Fragments of the substrate with the cells added nutrients and oxygen in small concentrations (1/16, atmospheric). In molecules of nutrients present isotopes of carbon and nitrogen 13C and 15N (they are heavier than the more common 12C and 14N), and by the way, how many of these isotopes will be in the cells after a certain period of time, evaluated, feeding the bacteria grow if they are, and if so, how quickly.
Age samples of clay were determined by the content of cobaltranged from 4.3 to 101.5 million years. Almost all, including the most ancient, found viable organisms from the groups Actinobacteria, Bacteroidetes, Firmicutes, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Chloroflexi , and some others.
Best cultivation yielded aerobes: they ate and quickly multiply. For 68 days from the start of incubation, some have increased the number of tens of thousands of times. Thus cells on average 3.09 times faster absorbed “heavy” nitrogen than carbon. From the addition of specific organic substances, the composition of the crops were practically independent, but depended on the time that has passed since the beginning of cultivation. It is also noted that many of the “resurrected” species are able to sporulate.
The authors notethat to resume the activity managed approximately 99.1 percent of the found microorganisms. It is obvious that these bacteria in their natural habitats should be an extremely low metabolic rate, otherwise they would not be “alive.” It is interesting to find out how they have adapted to the “slow life” and how much was modified for the 100 million years until the land has changed much of the flora and fauna. Most likely, and the evolutionary processes they went slower than terrestrial bacteria.
Bacteria and archaea are able to survive where others usually can not exist. For example, in the Iberian pyrite belt found cyanobacteria at a depth of 607 meters — and this despite the fact that such organisms need to photosynthesize, and sunlight so profoundly almost does not penetrate. And in the Atacama desert, where lack of other key conditions for photosynthesis — water, cyanobacteria have learned to produce this substance from plaster.