Tracking Down the First Oxygen Users

sciencehabit writes "None of us would be here today if, billions of years ago, a tiny, single-celled organism hadn't started using oxygen to make a living. Researchers don't know exactly when this happened, or why, but a team of scientists has come closer than ever before to finding out. They've identified the earliest known example of aerobic metabolism, the process of using oxygen as fuel. The discovery may even provide clues as to where the oxygen came from in the first place."

Oxidizer, not fuel

[Un pobre guey]

Oxygen is not the fuel. It is the oxidant to the fuel to release energy.

Re:Where the oxygen came from...

[SJHillman]

We already know the guys who produced the oxygen (or at least we have a good idea), we're interested in the ones who used it.

Re:Oxidizer, not fuel

[Megahard]

While "oxidation" is lexically derived from oxygen, there's a specific chemical definition for oxidation, namely the loss of electrons. LEO GER is the acronym beginning chemists learn. So while you can play around with the words the chemistry is well-defined. Oxygen is the oxidant because it transfers elections to the reductant or fuel or whatever you want to call it.

Re:Where the oxygen came from...

[turbidostato]

"My understanding ... is that atmospheric oxygen at levels high enough to sustain oxygen based metabolism came from plants and trees"

Your understanding is quite wrong.

By the time there were "plants and trees" the major part of the biosphere already was oxigen dependant.

The change of the atmosphere from reductive to oxidative predates trees by about two billion years -the start of the proterozoic age is marked about 2.4 billion years ago (with a strong spike around the precambric which still predates trees by about 300 million years).

Re:Oxidizer, not fuel

[mcgrew]

"Fuel" and "fire" and "burn" are all just lies to children.

Not lies to children, but the obvious. Of course, what may seem obvious often isn't ("the world is flat"). You and I know that if you combine a piece of wood and oxygen, both are converted, but you have to know how it works first. But at any rate, "fire" is a synonym of "oxidation". Fire is what you get when you combine a combustable material, oxygen, and heat. It's real, it's no lie. The combustable material is the fuel, oxygen is the oxident, and "burn" is the conversion of the fuel and oxygen to a different form. It's semantics, not lies.

Either that, or Iron is also a "fuel" with an end result of "rust" ash.

Actually, rust is steel's ashes, and you can make steel burn quite fast of you get it hot enough; ask any blacksmith. You can make sparklers out of pieces of wire coat hangers or bailing wire, coated with saltpeter mixed with flour or sugar. The sparkles on any sparkler you buy at a fireworks stand is the steel's flames, and that's exactly what you see if you put a thin piece of steel in a forge with the bellows going. Take the steel out of the fire and it sparkles like a sparkler, and leaves rust behind.

Re:Where the oxygen came from...

[djl4570]

Cyanobacteria changed the chemistry of the oceans as well. Before oxygen production the oceans contained large quantities of dissolved iron. When oxygen was produced the dissolved iron oxidized and precipitated out as rust. The banded iron formations are a relic of this epoch. It wasn't until the oceans reached equilibrium between oxygen and iron that surplus oxygen was released into the atmosphere.