Theoretical origin of life; subterranean extremophiles (Introduction)

by David Turell , Friday, November 24, 2017, 19:08 (2556 days ago) @ David Turell

Life, however weird is everywhere. Life seems to appear on Earth easily. why? the Earth is made for it!:

https://aeon.co/essays/deep-beneath-the-earths-surface-life-is-weird-and-wonderful?utm_...

"The deep Earth supports an entire biosphere, largely cut off from the surface world, and is still only beginning to be explored and understood.

"The amount of water in the subsurface is considerable. Globally, the freshwater reservoir in the subsurface is estimated to be up to 100 times as great as all the available fresh water in the rivers, lakes and swamps combined. This water, ranging in ages from seven years to 2 billion years, is being intensely studied by researchers because it defines the location and scope of deep life. We know now that the deep terrestrial subsurface is home to one quintillion simple (prokaryotic) cells. That is two to 20 times as many cells as live in all the open ocean. By some estimates, the deep biosphere could contain up to one third of Earth’s entire biomass.

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"Within this hellish environment, though, are crucial ingredients for nurturing life. Underground water reacts with minerals in the continental crust, and the longer the water has been trapped down there, the more time there has been for the results of those reactions to accumulate along the flow path. The slow reactions between water and rock dissolve minerals into the water, and break up some of the water molecules, producing molecular hydrogen. This hydrogen is an important fuel for microorganisms in the deep subsurface.

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"Old-water ecosystems are dominated by hydrogen-utilising microorganisms such as sulphate-reducing bacteria and methane-producing archaea. Those methane-producing archaea, or methanogens, are microbes that visually resemble bacteria but are so structurally and genetically distinct that they belong to a completely separate domain of life. Sulfate-reducing bacteria and methanogens are among the life forms that appeared earlier in the evolutionary history. In contrast, young-water ecosystems are dominated by metabolically diverse and versatile bacteria of the phylum proteobacteria.

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"Subsurface microorganisms are estimated to be extraordinarily long-lived. In our studies, they show a turnover time as slow as 1,000 years, meaning that they divide only once every few thousand years. To put it in perspective, the common gut bacterium E.coli divides once every 20 minutes. One of the long-standing questions is, how do the deep microbes achieve such a slow-motion lifestyle?

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"Our studies of the proteobacteria-dominated communities (collected from several sites 1 to 3 km below land surface) show that they share a high degree of similarity with each other, as determined by a genetic marker known as the 16S ribosomal RNA. However, the same functional traits are carried out by different taxa. This variation cannot be explained by physical separation of the sites, nor by each location’s unique physico-chemical features – normally the most ecologically influential factors for such segregation. Neither depth nor water-residence time appear to be a significant contributor to differences, either. Future investigations on the origins of subsurface microorganisms, along with their evolution and movement over the geological history, will aid our understanding of the biogeography, or living landscape, of the subsurface. (my bold)

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"The molecular data, together with isotope geochemistry and thermodynamic modelling, presented a unified story that the most successful group down there is the betaproteobacteria, a class of proteobacteria that obtain energy through a coupling of nitrate reduction and sulphur oxidation in order to fix carbon dioxide for cellular growth. The demand for nitrate among deep microbes was unexpected;... More interesting, we deduce that deep microbial groups have established strong, paired metabolic partnerships, or syntrophic relationships, which helps the organisms overcome the challenges of extracting the limited energy that originated from rocks. Rather than competing directly with each other, these microbes establish a win-win collaboration. (my bold)

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"The commonality of species on the surface and subsurface posed a consistent research challenge. At all times, we had to make extensive analysis to be sure that any specimen found was not the result of contamination of the mines where we were executing our research.

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"And our journey into the inner life of the Earth is just beginning. We are interested in determining whether species from the deep subsurface truly are as isolated as they seem, and if the migrations go in both directions. It is possible that some subsurface organisms reappear on the surface via hot springs."

Comment: Note the cooperative behaviour of these strange organisms. Not Darwinian at all. Life blooms easily on Earth with God's control. Perhaps life started in this weird area.