[set fair (OP)]

A friend was asking me about aphids and ants a couple of weeks ago, then I was watching Putin's weatherman describing a nuclear winter.

So the aphids feed on sap. In order to get enough protein they drink excess amounts of sugary water. This is secreted and ants lap up the calories and guard the aphids. It follows that ants have another source of protein. Maybe some ants and termites get their protein from wood. It may not contain much protein but the insects eat a specific fungus which they cultivate by providing it with wood. It would make sense if they use a  fungus which fixed nitrogen and produced protein. They've had millennia to coevolve with the fungus. So could we use the same fungus to feed ourselves on wood during a nuclear winter?

[alancalverd]

Yes. Try "Quorn" mycoprotein (other brands are available). It's a very adequate substitute for beef. Not sure what substrate they use, possibly sterilised horseshit (the real stuff, not what comes out of politicians' mouths) as preferred by mushroom growers, but maybe other organic fibers.

[paul cotter]

Referring to the original question "could we eat wood?", of course we can. I recommend oak for starters, mahogany for the main course and teak for desert. It will not deliver any nutrition unfortunately and one's dentist bill could be problematic. Bottom line: not recommended. Fungi cannot produce a high nitrogen content substance such as protein is without a feedstock with high nitrogen content- wood on it's own would not be sufficient. I know about those fungus cultivating ants but I don't know the details of what they use.

[Bored chemist]

Wood has a nitrogen content of about 0.1% or less.
Proteins are about 14% nitrogen.
So wood is about 1% protein.
But, if the fungus "eats" the wood, oxidises the cellulose and lignin for energy and keeps hold of the nitrogen then it can accumulate enough nitrogen to make its proteins from.
And, in principle, we can eat that protein.
Mushrooms are about 3% protein.
That's not bad.
But by the simple expedient of feeding the mushrooms to pigs, we can get bacon (36% protein)
The question is how much effort is that compared to growing beans?
OK, in a nuclear winter, that's not easy.
But, if we still have a society, we can still burn oil, run the generators and run the grow lights.

We know how to do that so it might be the easy option.

How about taking teh wood, treating it with dilute acid, neutralising it with chalk and then fermenting it to alcohol and distilling that off.
The nitrogen is left behind.
Add slaked lime  and redistill it and you will get ammonia.
You can react that with acid and feed that "fixed nitrogen" to ruminants like cattle and sheep (which can probably digest sawdust- though I doubt they would be happy or healthy).
The best thing to do is not vote for people like Putin, or those who praise/ admire him.

It's all fun and games until the energy runs out. Everything else can be recycled.

[alancalverd]

On my planet, there is plenty of nitrogen in the atmosphere. Following a nuclear war, quite a lot of it will be available as chemically reactive oxides. But there will be a shortage of edible sheep.

[Bored chemist]

On my planet the reactive oxides of nitrogen in a nuclear winter will be short-lived because they will be reduced by organic stuff in smoke.
The N2O might survive for a while, but I don't think it will achieve a lot.

[diverjohn]

So termites have bacteria in their guts that digest the normally indigestible cellulose. So what happens if we put some of those microbes into our GI tract ? will they produce sugars that we can digest?

[evan_au]

a  fungus which fixed nitrogen and produced protein

I see mixed responses on whether this is true.
- In digesting wood, fungi free the protein that was originally in the wood. They incorportae the released protein into the growing fungi.
- Some discussions say that fungi themselves can't fix atmospheric nitrogen - this is only done by prokaryotes
- Some fungi have a symbiotic relationship with bacteria that can fix atmospheric nitrogen.

This paper tested a theory that a particular fungus could fix atmospheric nitrogen by itself - they found that fungus growth was best when the symbiotic bacteria were present; they conclude it is the bacteria which fix nitrogen.
https://pubmed.ncbi.nlm.nih.gov/15381850/

[evan_au]

termites have bacteria in their guts that digest the normally indigestible cellulose

Many herbivores have microbes in their guts which digest cellulose.
- But the cellulose must first be crushed very thoroughly to give the microbes free access to the cellulose, which is why cows and sheep spend so much of the day chewing

The cellulose breakdown process is very slow, which is why herbivores have physically large guts, and long transit time
- The energy extracted is relatively low
- Humans have small relatively guts and medium transit time, which is possible because the food is "pre-digested" by external processes like grinding, fermenting and cooking.
- And cooked meat (protein+fat) forms a portion of the diet for many humans.
- So the conditions in our guts are probably not ideal to host cellulose-digesting bacteria
- And the anaerobic conditions in out guts are not suitable for nitrogen fixation.

Maybe we could genetically engineer bacteria that can quickly digest cellulose, and are at home in the human gut?
- But humans prefer to do things externally - in the environment or in domesticated animals
- It means we carry around less "baggage".