My human colony on Mars uses gentically modified archea/bacteria to turn dust collected from the surface of the planet into construction material and breathable oxygen. Technicalities of the processing method are not relevant, colonist put dust into machine and machine outputs iron sludge for further refinement with oxygen as a byproduct.
My question is: how much of this is science and how much is it fiction? How far are we in aspect of bioengeneering to be able to create such organisms (to my knowlegde no such archea/bacteria exists in nature). How efficient could be this process in terms of kg of raw materials processed per hour/day? What would be the biology of such organism: should it be fed scraps, exposed to sunlight, could it sustain itself from processing iron-oxide itself?
Edit:
Now I see a fundamental problem with my idea - unless the organisms arrange the iron into immediately usable structure, the colonists would still need to smelt the sludge at the same temerature as the raw ore, so the whole process didn't contribute anything in refining. Which is fine, maybe the bacteria coats itself with iron shell as sugested by @L.Dutch and fills the prepared form with a porous, iron slabs ready for construction after treating them with hydraulic press.
But assuming that the colonists would actually want to smelt (or rather bake) the resulting substance, is there a chemical compund that is:
- soluble in water (I assume the organism wouldn't survive without water),
- contains iron,
- can be synthesized from iron oxide and
- turns into iron under temperature significantly lower than what is required to smelt iron ore or in some other low-energy process