Theoretical origin of life; zircons with 4.1 byo evidence: (Introduction)

by David Turell @, Wednesday, October 10, 2018, 15:31 (721 days ago) @ dhw

As new extremophiles are found, they support the idea that life can handle any condition anywhere:

"In a surprise to scientists, cyanobacteria have been found thriving nearly 2,000 feet below the strange landscape, where sunlight, water, and nutrients are scarce. Researchers previously thought these microbes could survive only while basking in the sun's rays, although they are otherwise a versatile bunch; researchers have found them alive nearly everywhere on Earth.


"Cyanobacteria hold an important role in Earth's history: They were responsible for pumping oxygen into the atmosphere, paving the way for life to swim, slither, hop, gallop and fly around the planet. That's why the new study, published today in Proceedings of the National Academy of Sciences, is pushing scientists rethink what can survive deep below our feet—and perhaps even the types of critters we should look for in our search for life on Mars and beyond.


"Control samples helped the team determine that the microbes did not come from contamination due to the drilling fluid nor from processing in the lab. And the cyanobacteria were not found in random locations, as you might expect if the samples had been doused in contaminated liquid. Instead, they were congregating along the fractures in the rock, eking out an existence in the tiny pockets of air.


"The cyanobacteria don't appear to differ greatly from the same kinds of microbes that thrive at the surface. Metagenomic analysis suggests that they are descendants of rock-dwelling lineages who make their living in tough environments, such as in the desert or within shadowy caves.

"But even in the darkest of caves, cyanobacteria were thought to capture some of the scanty photons that ricochet into the space, using the energy from sunlight to split water and generate electrons during photosynthesis. So how do the subsurface bacteria survive without light?

"These cyanobacteria seem to be largely chowing down on hydrogen gas, as evidenced by the lack of hydrogen wherever there were lots of cyanobacteria in the cores. The gas is a common food source for microbes, particularly those in the subsurface that have few other options.

"The subsurface cyanobacteria, however, seem to be processing and releasing hydrogen electrons using coopted machinery that their surface kin use for photosynthesis. In particular, the microbes seem to be capitalizing on the system's “safety valve,” an electron release mechanism that produces small amounts of energy.

"Microbes on the surface don't really need this extra energy thanks to the abundance of sunlight, relying on the valve only to keep their cells from frying when light is aplenty. But the subsurface cyanobacteria seem to survive in part on the tiny sips of energy that result from the valve releasing pent-up electrons.

“'They don't have to replace much machinery to be able to do this.”

Even so, reusing the photosynthesis system is not necessarily a surprise, says Virginia Edgcomb, a marine and subsurface biosphere microbiologist who also wasn't involved in the study. Microorganisms that live in challenging environments have to be adaptable to survive.

“'It's sort of the 'eggs in a basket' analogy,” she says. “It doesn't make sense to put all your eggs in one basket, because you need to be flexible. You need to be able to use different things as carbon sources, different things as electron acceptors, because chances are your conditions are pretty limiting and unpredictable.'”

Comment: First, this shows life can figure out survival anywhere, but secondly, this is an ideal organism with which life was helped to evolve by progression to oxygen breathing complex forms. God as designer looks very bright in using this bacteria as a ratchet for evolution to progress. Photosynthesis is an extremely complex quantum process key to oxygen production, but can be altered to achieve survival using different energy sources. Only a clever designer could create this.

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