Sciencemadness Discussion Board

Efficient non-photosynthetic food production?

Polverone - 23-8-2006 at 22:15

Suppose for a moment that you had access to modern technology and plenty of coal, sawdust, or natural gas, but you didn't have access to sunlight. How could you produce food? You could burn fuel to generate electricity, power lights with the electricity, and grow plants or algae under the light, but that would be extremely inefficient. Are there any purely synthetic methods to convert carbon compounds into human-edible carbohydrates, lipids, and proteins? Can humans eat free amino acids in large quantities? What about racemic amino acids?

Are there are any organisms that don't rely on photosynthesis that could be used to process simple organic compounds into reasonably palatable or at least life-sustaining substances that humans can eat indefinitely? Let's assume that micronutrients are available from stockpiles or (at worst) can be made with the aid of artificial light photosynthesis; only macronutrients are needed.

The_Davster - 23-8-2006 at 22:32

I have heard of plants growing completly without light under the influence of ionizing radiation. But something also about that they would not produce flowers under these conditions.
Whether or not the plant is suitable for eathing after is another matter:P

What about underground fungii, like truffles.

I have wondered about eating pure nutrients before, I imagine you would live, but be hungry all the time as you would not have much mass in your stomach.

12AX7 - 23-8-2006 at 23:50

Meh, toss in some polyester fiber or something for the intestine to grab on to. :P

Ingredients for an IV drip would probably be easier, if neglectful of the GI tract. You still have the problem of synthesizing required vitamins and proteins, surely a complex synthesis if ever there was one. At least a couple kilo batch could last you a long time.

Tim

not_important - 24-8-2006 at 00:13

Saturated fatty acids are not difficult; the needed unstaturated ones are harder, both getting double bonds in the proper place and keeping to cis orientation. I don't know if you would need to build them up into fats proper to be digestable; they get freed as part of digestion but large amounts of the free acids might cause problems.

Carbohydrates - a mix of natural and unnatural is easy, formaldehyde and Ca(OH)2 catalyst. But I wouldn't want to consume that. I know there are a bit better methods, however I believe that it remains rather inefficient to put them together.

Amino acids; these suggest it may not be too bad to use the free acids alone

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&a...
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&a...
http://www.garfield.library.upenn.edu/classics1983/A1983RN13...

But several of the amino acids are most cheaply made by fermentation processes that use sugars as food; that links back to making carbohydrates.

I wonder about the need for bulk, and specifically the several types of fiber which seems to be needed for health and good intestinal fauna balance. Perhaps mineral mass, clays and such, can provide some useful bulk.

Making it palatable will take additional energy, texture and taste are expensive.


Autotrophic bateria exist, many are phototrophes but some are chemotrophic. So far as I know, all non-photosynthetic metazoa are saprobes; this include non-photosynthetic plants (most of which are parasites) and fungi.

Allowing sawdust is cheating in a way, it is produced by photosynthetic plants; the fungi you can grow on it are thus saprobes. You can even use it to feed ruminates, giving you milk and meat. But its just stored up sunlight, and stored for only a short time at that. Coal and oil are the same sort of thing, just that the sunlight was stored for a longer time; hydro and wind power are more recently sunlight.

I think it could be done, but suspect that it is more efficient to use the energy to make light to grow plants. You get many of the vitamins and minerals that way, so you don't have to fudge on micronutrients. True, photosynthesis isn't that efficient; factoring converting an energy source to light makes it even worse - overall will be a few tenths of a percent. But if you look at the overall yields of some synthesis of natural materials, factoring the cost of making reagents used, I think you'll find the conversion of fuel to food no more efficient that way.

You might be able to do something like using coal and water, or natural gas, to make synth gas and from that ammonia and methanol or methane(if using coal). Feed ammonia and methane to the proper chemotrophes; or alternatively convert methanol to formaldehyde and that to carbohydrate glop, and feed that and ammonia the other chemotrophes. Use those as food for other bacteria, protozoa, and even metazoa.

12AX7 - 24-8-2006 at 11:37

Why not use chemical routes the plants use? Them enzymes and proteins can get some pretty keen fits and efficiently produce lots of very specific molecules. That's probably the best you can do without directly using biology.

Tim

Elawr - 24-8-2006 at 12:33

Any flux of energy has the potential to organize simple compounds and elements into stuff we could eat. All you need is the right mechanism. Organisms run on nanotechnology of the biosynthetic variety. As soon as we can learn how to assemble chemicals akin to enzymes and ribsomes atom by atom, then we'll be close to licking the problem. Anything is possible. Look at the extremophilic life forms on our own world only recently discovered. Entire ecosystems based on sulfur-eating microbes near deep ocean volcanic vents. Thriving in the abyss at 200 degrees C and 50 atmospheres of pressure! It is as if theres a law of nature that says: wherever you have suitable precursors and an energy differential, life will appear. I predict we'll turn up some kind of weird life in our own solar sytem. Perhaps some kind of cryophilic life on Titan, with ammonia or methane instead of H20 as its solvent, and gleaning energy from the feeble sunlight.

chemoleo - 24-8-2006 at 17:14

Get cracking processes to make mono- and polyols, such as ethanol, ethyleneglycol, propylenglycol, butanol, etc, as well as fatty acids by oxidation of alcohols. Add a variety of ammonia and nitrate sources, urea, guanidine, you name it, and I am sure you can get E. coli to grow on it. Grow these, and kill the bacteria with heat. Use the resultant nutrient-rich solution to grow fungi, and yeast upon. These will in turn synthesise all the nutrients you ever would require, including vitamins, and so on (besides, many vitamins such as asc. acid can be made chemically). Simply centrifuge the yeast, crack it and make food paste from it.

Even better, genetically modified bacteria could easily be tailored to overproduce a certain metabolic product that is required in bulk for humans, such as glucose etc. Fibers etc could probably replaced by clays and minerals as mentioned, or it could be made in bulk by fungi.

The limiting step is to provide the bulk material from coal gas water to a simple growth medium upon which microorganisms could feed efficiently.

Granted, the food wont be tasty. But we could survive on it.

Twospoons - 24-8-2006 at 17:35

The ultimate approach would be engineered bacteria designed to live in the human gut, and convert coal directly. This symbiotic system provides the bacteria somewhere to live, cuts out all the efficiency losses of industrial processes (which are generally rubbish at producing complex organics from simple sources), and makes available the various conditions in the gut that might facilitate utilisation of something like coal (ie teeth for grinding, acids, enzymes, heat etc).

ziqquratu - 24-8-2006 at 17:54

If you have access to sawdust in unlimited amounts, then there's your organic carbon source - a system using cellulase (I'm guessing that this would be the name of a celluose-degrading enzyme!) to produce monomeric sugars, which could then be consumed as food and also used to drive fermentations to produce other necessary substances, including amino acids, lipids, and vitamins.

Also, I think there are organisms that use energy sources other than light (from memory they term these "chemotrophic" or something similar, as opposed to "phototrophic" for photosynthetic organisms). Bit fuzzy on the details, though. I THINK these are the sort of bacteria etc. you might find in ocean vents and so forth, where neither light nor oxygen are plentiful.

not_important - 24-8-2006 at 18:29

Quote:
Originally posted by 12AX7
Why not use chemical routes the plants use? Them enzymes and proteins can get some pretty keen fits and efficiently produce lots of very specific molecules. That's probably the best you can do without directly using biology.

Tim


Most biochemists wish we could use the full routes plants do, they expend much effort in understanding those routes and mimicing them. But right today we can't come close to the plants.

not_important - 24-8-2006 at 18:36

Quote:
Originally posted by ziqquratu
If you have access to sawdust in unlimited amounts, then there's your organic carbon source - a system using cellulase (I'm guessing that this would be the name of a celluose-degrading enzyme!) to produce monomeric sugars, which could then be consumed as food and also used to drive fermentations to produce other necessary substances, including amino acids, lipids, and vitamins.

Also, I think there are organisms that use energy sources other than light (from memory they term these "chemotrophic" or something similar, as opposed to "phototrophic" for photosynthetic organisms). Bit fuzzy on the details, though. I THINK these are the sort of bacteria etc. you might find in ocean vents and so forth, where neither light nor oxygen are plentiful.


Some bacteria and many fungi can utilize celluose directly; fungi can often use the lignin. Unfortunately a lot of these don't produce what could be considered as food.

You are going to need a nitrogen source, be it artifical NH3, photosynthetic bateria fixing nitrogen, or the few chemotrophic rather fussy bacteria that can.

And again, getting the essential unstaturated fatty acids isn't going to be easy, currently the biological route is the most efficient and generally means photosynthetic means.

Polverone - 25-8-2006 at 19:33

Thanks for the replies. It seems that sawdust may make things significantly easier, if not actually easy. No non-photosynthetic organisms will produce the essential unsaturated fatty acids? So be it then.

I was actually wondering about this in a science-fictional sort of way: how would you provide food for (say) a long-term habitat orbiting Saturn? You wouldn't really have coal and natural gas, but you'd have carbon that could be recycled into simple organics (and more, if you pay the price) from CO2. The sun's light would be very weak at that distance. I was wondering if there was any more efficient to produce sustenance than growing things under artificial light. If the answer was "yes" I was going to consider its terrestrial application, as a potential way method of producing extremely cheap (if unpalatable) food, hence the inclusion of sawdust, but it looks like things may not go that far.

not_important - 26-8-2006 at 00:03

Some bacteria make poly-unsaturates, and some of those are not photosynthetic. But of those most are saprobes, meaning you will be feeding them biological materials, and a lot grow best in conditions found several km underwater.

It seems likely that bacteria could be bioengineered to produce enough PUFAs to be useful. But it's still likely you will need to feed them sugars or organic acids, and possibly organic/biological nitrogen.

There are problems or potential problems with new biological sources of food. Do a search on 'quorn' or 'soy allergy'. They same thing holds true for purely synthetic foodstuffs, they may require purification that removes side products to concentrations less than a part per million.

The thing is that on Earth you don't have to generate light, it happens automatically every day. Plants can use that low intensity energy, they've spent several billion years learning how to. Water is more of an issue than light. Out at Saturn, with 1% of the sunlight Earth gets, how to get and utilize energy is much more of a concern.

In terms of a space colony, I think that you would find that biological systems would compete with tearing everything down to carbon oxides and water, or even simply organics, and then builing up foodstuffs. Shine light on cyanobacteria, algae, or plants, and not only do they assemble carbohydrates, proteins, and fats that your body is used to, but they make O2 as well.

There's a lot that can been done to do better at using what we currently have. Grind up garbage, mix it with sewage. Ferment that to get methane, feed the sludge to fungi and bateria that break down the more resistant materials. Feed the CO2 produced to plants, algae or water plants growing in the output water; those can go into the methane fermentation or be used as animal feed. The water, with its load of combined nitrohen and phosphorus, can be used to irrigate; although an occasional low mineral content flooding of the fields will be needed to prevent mineral (especially sodium) buildup unless there is enough of a wet season.

Ruminates, as food or dairy animals, don't have to be feed diets that include grains such as corn or wheat, much of their food can be cellulose and inorganic or simple organic nitrogen; the bacteria in their gut turn tha into fatty acids and proteins. Humans can't directly use that cellulose, but they can eat cheeseburgers.

I think that the human aspect would be very important. People are fairly resistant to eating some new foods, or giving up their old ones. Set up a sample tray with the items clearly labled in the local languages; put lamb, beef, pork, guinea pig, dog, snake, blood pudding, tripe, sweetbreads, inago, zaza-mushi, jumiles, witchety grubs, palm weevil larva, milk, cheese, kaffir, dahi, eggs, tofu, tempe, natto, balou balou, soumbara, iru, ugba, kenima, tape ketan/ketella, poi, kim-chi, hum-choy, tempoyak on it. Go to some spot in the world, invite the locals to sample, observe their reactions. If some of those foods violate religious restrictions, be prepared to run.

Even purely synthetic foods may have problems. I know several people that have exteme food allergies, as in allergic to most foods they grew up with. In the process of determing what they are allergic to, and sometimes if they are reacting to whatever they've eaten recently, they had to live off one of several special 'food' stuffs that are effectively synthetic food. One described theirs as "laundry starch mixed with chalk, but tasting worse". They had a real hard time sticking to the stuff, they'd fall off the wagon and eat something normal knowing that they'd be puking their guts out in a few hours - "it's worth it". Making synthetic, or even microbial or other alternatives, into something palatable may take a lot of work and add appreciably to the cost of the food. Quorn costs more than meat, as an example.

Fried wood louse, I mean Land Lobster(tm), anyone?