Microbes that use iron like oxygen

[Plazma Inferno!]

A pair of papers from a UW–Madison geoscience lab shed light on a curious group of bacteria that use iron in much the same way that animals use oxygen: to soak up electrons during biochemical reactions. When organisms—whether bacteria or animal—oxidize carbohydrates, electrons must go somewhere.
The studies can shed some light on the perennial question of how life arose, but they also have slightly more practical applications in the search for life in space.

http://phys.org/news/2016-04-microbes-iron-oxygen.html

 

[exchemist]

A pair of papers from a UW–Madison geoscience lab shed light on a curious group of bacteria that use iron in much the same way that animals use oxygen: to soak up electrons during biochemical reactions. When organisms—whether bacteria or animal—oxidize carbohydrates, electrons must go somewhere.
The studies can shed some light on the perennial question of how life arose, but they also have slightly more practical applications in the search for life in space.

http://phys.org/news/2016-04-microbes-iron-oxygen.html

Yes, it reminds us that there are several oxidation reactions used in natural metabolism, not just the one involving free oxygen that we are so familiar with. This one seems to be Fe (III) + e- -> Fe (II), i.e. exploiting the two oxidation state of ionic iron. There are also sulphate-reducing bacteria that use the oxidation states of sulphur.

Since free oxygen would have arrived on earth only after photosynthesis began, long after life itself started, these metabolic processes may be the oldest in terrestrial biology.

 

[timojin]

Yes, it reminds us that there are several oxidation reactions used in natural metabolism, not just the one involving free oxygen that we are so familiar with. This one seems to be Fe (III) + e- -> Fe (II), i.e. exploiting the two oxidation state of ionic iron. There are also sulphate-reducing bacteria that use the oxidation states of sulphur.

Since free oxygen would have arrived on earth only after photosynthesis began, long after life itself started, these metabolic processes may be the oldest in terrestrial biology.

Adding a little to your discussion . Mars the red planet It is assumed the red color of the soil is Fe2O3, if there would be bacteria on Mars that trieve on reducing Fe (III ) --- Fe (II ) there should be Oxygen available on Mars. As far Sulfur reducing bacteria I have in my water well, from time to time I get H2S odor in my water.

 

[iceaura]

The UW-Madison microbiology guys have been working on bacterial use of iron for electron handling in redox reactions since this guy joined their faculty: https://www.researchgate.net/profile/Brian_Fox4/publications

He wrote his PhD thesis on his discovery of one such structure, decades ago when he was a hot Irish fiddle player and a newly married young man.

One of his motives, then and since, is the bacterial remediation of various industrial contaminations.

Just for context. Liberalism: it works.

 

[timojin]

The UW-Madison microbiology guys have been working on bacterial use of iron for electron handling in redox reactions since this guy joined their faculty: https://www.researchgate.net/profile/Brian_Fox4/publications

He wrote his PhD thesis on his discovery of one such structure, decades ago when he was a hot Irish fiddle player and a newly married young man.

One of his motives, then and since, is the bacterial remediation of various industrial contaminations.

Just for context. Liberalism: it works.

I am not surprised about old work, it is known in the oil industry and coal industry about bacteria living on redox

 

[exchemist]

The UW-Madison microbiology guys have been working on bacterial use of iron for electron handling in redox reactions since this guy joined their faculty: https://www.researchgate.net/profile/Brian_Fox4/publications

He wrote his PhD thesis on his discovery of one such structure, decades ago when he was a hot Irish fiddle player and a newly married young man.

One of his motives, then and since, is the bacterial remediation of various industrial contaminations.

Just for context. Liberalism: it works.

Er...."liberalism"? I don't follow - can you explain a bit more?

(P.S. And quickly, before Wellwisher arrives! )

 

[Yazata]

A pair of papers from a UW–Madison geoscience lab shed light on a curious group of bacteria that use iron in much the same way that animals use oxygen: to soak up electrons during biochemical reactions. When organisms—whether bacteria or animal—oxidize carbohydrates, electrons must go somewhere.
The studies can shed some light on the perennial question of how life arose, but they also have slightly more practical applications in the search for life in space.

http://phys.org/news/2016-04-microbes-iron-oxygen.html

The news isn't that bacteria can use iron as electron-accepters in their respiration, that's been known for decades. (Iron is actually a rather good electron acceptor, certainly better than some of the other things bacteria use, though not as good as oxygen.) If there's anything new here, it's something about the details of the biochemistry that gets it done, or about the genomics that codes for it. The physorg article was vague about that, perhaps the journalist didn't understand it.

I found it odd that the article didn't name the bacterial genus either. (At least I don't recall seeing it.) I'm guessing that it's Geobacter.

https://en.wikipedia.org/wiki/Geobacter

Geobacter is one of the more interesting bacteria out there. It's an anaerobe (facultative?) that can use a number of metals as well as other things as electron acceptors in its respiration. Because it can't bring the iron it's using inside its cell, it extrudes tentacle-like cellular processes that contain electricity-conductive proteins. Interestingly, multiple Geobacter species cooperate together in environments where none could survive alone, each performing part of a larger biochemical task, using these biological wires of theirs to transfer electrons among themselves. That has led to their being the subject of research into biological fuel cells.

They are also of research interest in environmental cleanup work. It seems that they can reduce hydrocarbons and halogenated compounds that were resistant to other attempts to get them out of the environment. They can apparently respire using uranium as their electron accepter and make uranium precipitate out of water. I don't know the details of any of this and Exchemist can probably understand it better than me.

I don't understand how left-politics is relevant to the microbiology.

 

[Billy T]

Anerobic bacteria exist that can oxidize (in the general chemical sense - give electron to some substance) many things, including sulpher in the hot deep sea vents and many compounds. They "ruled the Earth" until green plants evolved, and polluted the atmosphere with oxygen. Now they find shelter in the guts of many animals, humans included (E-coli etc.) that still have very low O2 levels.

What surprised me was they can find enough un-oxidized iron to live. Are they mainly found deep inside the earth's crust.

 

[exchemist]

Anerobic bacteria exist that can oxidize (in the general chemical sense - give electron to some substance) many things, including sulpher in the hot deep sea vents and many compounds. They "ruled the Earth" until green plants evolved, and polluted the atmosphere with oxygen. Now they find shelter in the guts of many animals, humans included (E-coli etc.) that still have very low O2 levels.

What surprised me was they can find enough un-oxidized iron to live. Are they mainly found deep inside the earth's crust.

Billy, I think you are possibly getting confused. These bacteria reduce iron rather than oxidising it, just as sulphate-reducing bacteria reduce sulphur.

What they are doing is using iron or sulphur instead of oxygen in their respiration, i.e. as an oxidiser. When we breathe in oxygen and breathe out carbon dioxide our metabolism is oxidising carbohydrates to obtain energy. However, because the carbohydrate is oxidised, it follows that the oxygen is itself reduced. (The oxidation state of molecular oxygen is zero, while that in CO2 is -2.) Notionally giving electrons to something reduces it. Notionally abstracting electrons from it oxidises it.

For any interested readers, a simple example is, when you burn sodium: Na (zero) goes to Na (+1), while O2 (zero) goes to O (-2), and in the process oxygen strips an electron from sodium (both notionally and really in this case, as sodium oxide is ionic). If you burn coke (carbon), the resulting carbon dioxide is a covalent molecule rather than ionic, but to determine the oxidation state you pretend it is ionic and that 4 electrons have been stripped from carbon and 2 given to each oxygen, giving carbon an oxidation state of +4 and oxygen one of -2. The electrons are thus only "removed" notionally, in the covalent case. The concept of oxidation states derives from pretending that all compounds are ionic and that the electrons are given to the more electronegative element - oxygen in this case but it could equally be a halogen such as chlorine. It has less use in compounds with large numbers of elements and where it is hard to determine unambiguously which are the more electronegative of them.

In these bacteria, the iron is not the fuel, it is the oxidiser and is thus reduced, while the fuel (again carbohydrate) is oxidised.

P.S. Oxidation states are a useful concept in chemistry but can be something of a bastard to apply correctly - and even worse to explain.

 

[Billy T]

Billy, I think you are possibly getting confused. ...

No I spoke of the process of oxidation, and carefully defined it:
"oxidize (in the general chemical sense - give electron to some substance)"
As too many think "oxidation" must envolve oxygen.

When you speak of "iron being reduced," you speak of only one side of a binary process. I spoke of the whole chemical process, called "oxidation" which is the chemical transfer of one (or more) electrons from A to B.

 

[exchemist]

No I spoke of the process of oxidation, and carefully defined it:
"oxidize (in the general chemical sense - give electron to some substance)"
As too many think "oxidation" must envolve oxygen.

When you speak of "iron being reduced," you speak of only one side of a binary process. I spoke of the whole chemical process, called "oxidation" which is the chemical transfer of one (or more) electrons from A to B.

To give an electron to some substance is to reduce it:https://simple.wikipedia.org/wiki/Reduction_(chemistry)

Oxidation involves removing electrons from the thing being oxidised.

 

[timojin]

Anerobic bacteria exist that can oxidize (in the general chemical sense - give electron to some substance) many things, including sulpher in the hot deep sea vents and many compounds. They "ruled the Earth" until green plants evolved, and polluted the atmosphere with oxygen. Now they find shelter in the guts of many animals, humans included (E-coli etc.) that still have very low O2 levels.

What surprised me was they can find enough un-oxidized iron to live. Are they mainly found deep inside the earth's crust.

There is also interesting for me . If iron gets reduced who is the reducing agent , If we assume the initial is Fe3O4 = FeO, + Fe2O3 = FeO + Fe+++ O2 So Oxygen gets released. So I assume The bacteria reduces the Iron oxide not from Fe2O3 but from Fe3O4

 

[exchemist]

There is also interesting for me . If iron gets reduced who is the reducing agent , If we assume the initial is Fe3O4 = FeO, + Fe2O3 = FeO + Fe+++ O2 So Oxygen gets released. So I assume The bacteria reduces the Iron oxide not from Fe2O3 but from Fe3O4

The reducing agent is the carbohydrate that the organism is oxidising to obtain energy.

 

[timojin]

The reducing agent is the carbohydrate that the organism is oxidising to obtain energy.

Im not sure if it is deep down in the earth ?

 

[exchemist]

Im not sure if it is deep down in the earth ?

Don't forget that there are also bacteria that can chemosynthesise carbohydrate from CO2 and water, just as plants photosynthesise. So you do not have to have sunlight to have carbohydrate.

 

[Billy T]

To give an electron to some substance is to reduce it:https://simple.wikipedia.org/wiki/Reduction_(chemistry)

Oxidation involves removing electrons from the thing being oxidised.

I have no argument with this.* Yes one can speak of some subatance being reduced or of some substance being oxidized. They are the two halfs of the process I call oxidation (or could call reduction, but usually don't).

Again I was speaking of the whole process - One or more electrons being transfered for A to B, not of the half processes separately. That I spoke of the whold process does not imply I was confused.

* But note, in parallel with the part of your text now bold, the process of oxidation also involves adding electrons to the thing being reduced. For me, it is desirable to reserve term "oxidation" (and /or "reduction") as the names of the process, not as parts of a process. Then I speak of one thing as being reduced or another thing as being oxidized.

 

[exchemist]

I have argument with this. Yes one can speak of some subatance being reduced or of some substance being oxidized. They are the two halfs of the process I call oxidation (or could call reduction, but usually don't).

Again I was speaking of the whole process - One or more electrons being transfered for A to B, not of the half processes separately. That I spoke of the whold process does not imply I was confused.

If what you mean is that a redox reaction involves electron transfer, I am fine with that. In any redox reaction you have a substance that is oxidised and a substance that is reduced. All I am pointing out is that the electrons are (notionally, at least) given to the substance being reduced ; and taken from the one being oxidised.

What you originally said appeared - to my eyes at least - to be the opposite, viz. : ".... bacteria exist that can oxidize (in the general chemical sense - give electron to some substance) many things....." This, I felt, was liable to cause confusion to other readers.

 

[Billy T]

If what you mean is that a redox reaction involves electron transfer, I am fine with that. ...

Yes that is what I mean. I agree "redox" is a better term for the whole process I usually call oxidation, but as noted earlier could just as well have called reduction. It is so long ago that I did any chemistry, that I had forgotten the redox term.

BTW, you quoted me before I had edited to put the missing "no" in the first sentence. I'm a little dyslexic and read what should be there, but note it is not when it gets posted.

 

[exchemist]

Yes that is what I mean. I agree "redox" is a better term for the whole process I usually call oxidation, but as noted earlier could just as well have called reduction. It is so long ago that I did any chemistry, that I had forgotten the redox term.

BTW, you quoted me before I had edited to put the missing "no" in the first sentence. I'm a little dyslexic and read what should be there, but note it is not when it gets posted.

Ah OK, all is now clear.