Methane Photosynthesis

[Vaktus]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4284464/

I found a paper exploring non-oxygenic photosynthesis. One of which where methane takes the place of carbon dioxide and hydrogen the place of oxygen.

CH4+H2O+photons→CH2O+2H2

Apparently, this method uses a fourth of the energy required for organisms to create biomass than than our own form of photosynthesis. Not only that, but when one gram of that biomass is broken down, it only gives a fourth of the energy of oxygenic biomass.


This makes me wonder what life would be like on such a world. Thoughts?

[iancampbell]

Given the figures you put forward, it ought to mean that life on such a world would have roughly the same energy budget as ours - albeit with four times the material throughput. One thing that might help is that hydrogen diffuses a lot better than oxygen does.

One thing I don't know about is any hydrogen carrier system comparable to haemoglobin/haemocyanin (Earthly organisms use both).

On top of all that, if the energy requirement is lower then perhaps it works with lower-energy photons, so a hydrogen cycle would be favoured on a planet of a cool star?

In any case, we may actually be able to check. Titan has significant levels of hydrogen and methane.

[Drashner1]

Perhaps something like this could be the basis for the Muuh and the biosphere of Muuhhome? There was a recent question about the Muuhhome biosphere.

Todd

[Vaktus]

Perhaps something like this could be the basis for the Muuh and the biosphere of Muuhhome? There was a recent question about the Muuhhome biosphere.

Todd

Well, I'm not sure if it could be used for a Muuhome. In the paper I posted, if I read it correctly, their environmental conditions for this type of photosynthesis uses liquid water. Maybe this process can use water-ice instead?

Also, the life that uses this method of photosynthesis would most likely have far more energy to use than the biosphere of titan worlds unless they receive only a small amount of photons.

[Vaktus]

Given the figures you put forward, it ought to mean that life on such a world would have roughly the same energy budget as ours - albeit with four times the material throughput. One thing that might help is that hydrogen diffuses a lot better than oxygen does.

One thing I don't know about is any hydrogen carrier system comparable to haemoglobin/haemocyanin (Earthly organisms use both).

On top of all that, if the energy requirement is lower then perhaps it works with lower-energy photons, so a hydrogen cycle would be favoured on a planet of a cool star?

In any case, we may actually be able to check. Titan has significant levels of hydrogen and methane.

Maybe for a carrier system they use hydrides?

I think this type of photosynthesis uses liquid water instead of the water-ice found on Titan and other similar worlds.

[stevebowers]

This would be useful for sky-plankton in the atmosphere of a gas giant. I imagine skyplanton cells to look like bubbles of pure hydrogen, using the tiny density difference between hydrogen and helium to stay afloat. It would be very useful if the photosynthesis process used (or produced hydrogen) as a major component.

[Rynn]

My initial thoughts are: Cool! Next thoughts: this would be really useful to engineer into organisms or specialist crops to deal with atmospheric methane pollution. The thought after that is what to do with all the formaldehyde. Formaldehyde does quickly break down and on a world where this is the predominant photosynthesis reaction it stands to reason that life would have evolved a resistance to it, or it would be quickly broke down by the plants for other uses. In fact formaldehyde can be combined with a variety of organic molecules to form plastics. So the plants of this world might not only be weird in their method of photosynthesis they may also have naturally occuring plastic tissues...

This would be useful for sky-plankton in the atmosphere of a gas giant. I imagine skyplanton cells to look like bubbles of pure hydrogen, using the tiny density difference between hydrogen and helium to stay afloat. It would be very useful if the photosynthesis process used (or produced hydrogen) as a major component.

Plastic sky-plankton in gas giants...Awesome

[Vaktus]

This would be useful for sky-plankton in the atmosphere of a gas giant. I imagine skyplanton cells to look like bubbles of pure hydrogen, using the tiny density difference between hydrogen and helium to stay afloat. It would be very useful if the photosynthesis process used (or produced hydrogen) as a major component.

Perhaps this reaction would be better?

CO2(aq) + 4 H2(aq)→CH4(aq) + 2 H2O(aq)

though, this reaction produces less energy the colder the environment is and lesser the CO2 is in the atmosphere.

[stevebowers]

Carbon compounds in a Eujovian gas giant tend to be methane already, so this might be problematic.

[iancampbell]

One possible energy-yielding reaction in a reducing atmosphere might be the hydrogenation of multiply-bonded molecules - ideally, all the way to methane. For example, although I haven't done the maths I feel this reaction would be exothermic:

C2H2 + 3H2 = 2CH4

(a triply-bonded compound being fully hydrogenated)

This reaction goes very slowly indeed without catalysis, but enzymes do more difficult things than this.