anoxygenic photosynthesis to generate new water at hydrogen vents

doctordirt · 2017-06-22 19:19:51

Anoxygenic photosynthesis evolved on earth more than 3800 years ago.

Although Mars has no surface bodies of liquid water, hydrogen vents could provide the substrate to create water via anoxygenic photosynthesis.

Oxygenic photosynthesis, overall reaction:

H2O + CO2 = CH2O (carbohydrate) + O2

Anoxygenic photosynthesis using hydrogen, overall reaction:

2H2 + CO2 = CH2O + H2O

There are still species of cyanobacteria on Earth that can go both ways. In the presence of hydrogen, they turn off the oxygenic photosystem and use the (far more productive) hydrogen-based photosystem. Without hydrogen, they resort to the (less productive) oxygenic photosynthesis.

So, with sunlight and a small puddle of water at a hydrogen vent, a colony of these cyanobacteria could generate more and more water, limited only by the supply of hydrogen.

Once the puddle grows large enough, these same cyanobacteria could colonize outward, resorting to oxygenic photosynthesis.

Although oxygenic photosynthesis consumes water, the oxygen produced can be used to make more water:

e.g. CH2O + O2 = CO2 + H2O

Robert R. Northup Ph.D. biogeochemist

RobertDyck · 2017-06-22 19:47:58

If you could find a hydrogen vent, sure. Black smokers on Earth's ocean floor use chemosynthesis, they don't need light at all. Bacteria and archaea use minerals and hydrogen directly as their energy source.

The Microbes That Keep Hydrothermal Vents Pumping

Methanopyrus kandleri is a heat- and salt-loving species of Archaea that makes its home on the chimney walls of smokers. It harvests energy from hydrogen gas and releases methane, a process known as methanogenesis. It's this process that gives the microbe its name: Methanopyrus translates to “methane fire.” Methanopyrus kandleri has been isolated from hydrothermal sediments at Kolbeinsey Ridge off the coast of Iceland and the Guaymas Basin in the Gulf of California. In the laboratory its cells can even divide at 122°C, the highest temperature known to be compatible with microbial growth, though it grows best at 98°C.
Scientists isolated species of Pyrolobus (“fire lobe”) and Pyrodictium (“fire network”) Archaea also from chimney walls. These heat-loving microbes (which grow optimally at temperatures above 100°C) get their energy from hydrogen gas and produce hydrogen sulfide from sulfur compounds from the vents. Hydrogen sulfide is highly toxic to most animals, including people. However, animals at hydrothermal vents have special biochemical adaptations that protect them from hydrogen sulfide.

SpaceNut · 2017-06-22 20:16:08

Would a methane vent due as there seems to be a chance that these exist on mars....

doctordirt · 2017-06-22 22:28:47

There is clear evidence that hydrogen is continuously escaping the Martian atmosphere.

Absent an underground source venting new hydrogen to the surface, all hydrogen should have left the planet thousands of millions of years ago.

Hydrogen can be combined with carbon dioxide to generate methane (methanogenesis) and water, but the organisms that do this can only capture the chemical energy of the components.

Anoxygenic photosynthesis also captures sunlight energy, in addition to the chemical energy of hydrogen oxidation, for even greater growth yield.

Methane isn't so useful as substrate, unless fairly strong oxidant is available.

I suspect that methane is too light to remain in the Martian atmosphere, as is the case with water vapor.

RobertDyck · 2017-06-22 22:48:45

I would say "Ok", but I have to point out a weakness in your argument. I hope you won't take this as an attack. I greatly appreciate a new perspective, new ideas. But science criticizes everything, every new idea must withstand critical review.

You claim the fact hydrogen has been measured escaping into space is the reason there must be hydrogen vents. That doesn't hold. Yes, there is hydrogen escaping. However, solar wind impacts the upper most atmosphere directly. That imparts enough energy to dissociate water into monoatomic hydrogen and hydroxyl (H+ and OH-). And hydrogen can be accelerated to escape velocity. So the expected source of hydrogen is water. The Earth is bombarded by snowball size ice meteoroids every day. They deliver new water to our planet. Furthermore volcanoes release water. Much of the water is from subduction, but there could be water from the mantle as well. Mars has a lot of meteors; just look at its surface. Orbiters haven't measured meteor impacts, but based on craters its expected there are quite a few. So Mars should get snowball meteoroids just as Earth does. And the frozen pack ice of Elysium Planetia is believed to have come from volcanic eruption of Cerberus Fossae fissures just 2 to 10 million years ago. Most of that water was from melting permafrost, but it still means active volcanism. Volatiles in volcanic eruptions contribute to the atmosphere and hydrosphere.

louis · 2017-06-23 05:30:35

Reminds me - these critters are pretty interesting too:

https://en.wikipedia.org/wiki/Iron-oxidizing_bacteria

Iron oxidising bacteria - could we use them on Mars to make oxygen out of iron oxide? Don't know whether it would be a less energy intensive method than others.

Last edited by louis (2017-06-23 08:05:15)

Antius · 2017-06-23 07:53:45

louis wrote:

Reminds me - these critters are pretty interesting too:

https://en.wikipedia.org/wiki/Iron-oxidizing_bacteria
Iron oxidising bacteria - could we use them on Mars to make oxygen out of iron oxide? Don't whether it would be a less energy intensive method than others.

Cosmic rays must generate small quantities of oxygen and hydrogen through radiolysis of water in the Martian regolith. Maybe iron-oxidising bacteria are living in the regolith right now.

The Martian regolith is 0.2-1.0% perchlorate by weight. This is a powerful oxidising agent. Some bacteria have enzymes capable of breaking this down into free oxygen and chloride compounds.

This could be one admittedly dubious explanation for the free organics found on Mars.

doctordirt · 2017-06-23 17:31:19

Admittedly, I never studied Martian geochemistry before.

I guess with no ozone shield, UV has had thousands of millions of years to bring about photooxidation.

It almost sounds hopeless to establish microorganisms, even if you could create liquid water for them, with so much perchlorate around.

doctordirt · 2017-06-23 17:40:23

louis wrote:

Reminds me - these critters are pretty interesting too:

https://en.wikipedia.org/wiki/Iron-oxidizing_bacteria
Iron oxidising bacteria - could we use them on Mars to make oxygen out of iron oxide? Don't know whether it would be a less energy intensive method than others.

Iron oxidizing bacteria consume oxygen, rather than produce it. Oxygenic photosynthesis required at least 1000 million years of oxygen production just to rust away the iron in the earth's crust, before any traces of free oxygen could begin to accumulate in the atmosphere.

The popular misconception that the rise of oxygenic photosynthesis caused an "oxygen catastrophe" mass extinction is proven wrong in the long record of banded iron formations. There was never a sudden rise in oxygen. It was an incredibly slow process.

doctordirt · 2017-06-23 17:46:02

RobertDyck wrote:

I would say "Ok", but I have to point out a weakness in your argument. I hope you won't take this as an attack. I greatly appreciate a new perspective, new ideas. But science criticizes everything, every new idea must withstand critical review.
You claim the fact hydrogen has been measured escaping into space is the reason there must be hydrogen vents. That doesn't hold. Yes, there is hydrogen escaping. However, solar wind impacts the upper most atmosphere directly. That imparts enough energy to dissociate water into monoatomic hydrogen and hydroxyl (H+ and OH-). And hydrogen can be accelerated to escape velocity. So the expected source of hydrogen is water. The Earth is bombarded by snowball size ice meteoroids every day. They deliver new water to our planet. Furthermore volcanoes release water. Much of the water is from subduction, but there could be water from the mantle as well. Mars has a lot of meteors; just look at its surface. Orbiters haven't measured meteor impacts, but based on craters its expected there are quite a few. So Mars should get snowball meteoroids just as Earth does. And the frozen pack ice of Elysium Planetia is believed to have come from volcanic eruption of Cerberus Fossae fissures just 2 to 10 million years ago. Most of that water was from melting permafrost, but it still means active volcanism. Volatiles in volcanic eruptions contribute to the atmosphere and hydrosphere.

You're right. I finally looked it up. They are talking about monoatomic hydrogen escaping, not H2.

On the other hand, based on Earth's geochemistry, unless Mars has cooled so much that there is no movement of magma, it should still be venting hydrogen (H2) somewhere. In fact, I could swear I saw a news story less than two weeks ago about this having been confirmed.

SpaceNut · 2017-06-23 18:37:59

Maybe from a Maven report... Top 10 Mars Discoveries Made By MAVEN In 1,000 Days In Orbit Around The Red Planet

3. The amount of hydrogen in the upper atmosphere varies by a factor of 10 during different seasons through the Martian year. The hydrogen comes from the lower atmosphere, where sunlight breaks up water into hydrogen and oxygen. However, the seasonal variation is both unexpected and not well understood.

https://www.nasa.gov/content/goddard/ma … here-loss/

knightdepaix · 2017-06-24 22:15:37

Antius wrote:

Cosmic rays must generate small quantities of oxygen and hydrogen through radiolysis of water in the Martian regolith.
The Martian regolith is 0.2-1.0% perchlorate by weight. This is a powerful oxidising agent. Some bacteria have enzymes capable of breaking this down into free oxygen and chloride compounds.

louis wrote:

https://en.wikipedia.org/wiki/Iron-oxidizing_bacteria
Iron oxidising bacteria - could we use them on Mars to make oxygen out of iron oxide? Don't know whether it would be a less energy intensive method than others.

Can there be a mutualism between two types of iron-oxidizing and metal reducing bacteria at methane venting sites? The iron oxidizing ones oxidize perchlorates and oxides to free oxygen by photosynthesis or methane to carbon dioxide and water. They pass on metal ions including iron. The metal reducing bacteria takes the metal ions, carbon dioxide and water and reduce the ions to free metals by photosynthesis or methane oxidation. In other words, photosyntheses take place for both types when light radiation is enough, methane oxidation -- or hydrogen for what it worth -- when light radiation is not enough. Similar to how the light curve describes compensation point for plants on Earth, the rate of photosynthesis generating free metal and oxygen relates the rate of respiration generating carbon dioxide and water.

How much methane are left in Mars for bacterial uses?

Or a three party mutualism also include the photosynthetic plants -- or bacteria -- that pick up the carbon dioxide and water from aforementioned bacteria and release carbohydrates and oxygen. The plants pass on some amount of carbohydrates that the bacteria use in addition of methane.

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#1 2017-06-22 19:19:51

anoxygenic photosynthesis to generate new water at hydrogen vents

#2 2017-06-22 19:47:58

Re: anoxygenic photosynthesis to generate new water at hydrogen vents

#3 2017-06-22 20:16:08

Re: anoxygenic photosynthesis to generate new water at hydrogen vents

#4 2017-06-22 22:28:47

Re: anoxygenic photosynthesis to generate new water at hydrogen vents

#5 2017-06-22 22:48:45

Re: anoxygenic photosynthesis to generate new water at hydrogen vents

#6 2017-06-23 05:30:35

Re: anoxygenic photosynthesis to generate new water at hydrogen vents

#7 2017-06-23 07:53:45

Re: anoxygenic photosynthesis to generate new water at hydrogen vents

#8 2017-06-23 17:31:19

Re: anoxygenic photosynthesis to generate new water at hydrogen vents

#9 2017-06-23 17:40:23

Re: anoxygenic photosynthesis to generate new water at hydrogen vents

#10 2017-06-23 17:46:02

Re: anoxygenic photosynthesis to generate new water at hydrogen vents

#11 2017-06-23 18:37:59

Re: anoxygenic photosynthesis to generate new water at hydrogen vents

#12 2017-06-24 22:15:37

Re: anoxygenic photosynthesis to generate new water at hydrogen vents

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