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Exploring the idea of "living" matter, (possibly non-carbon based if necessary), decomposing by bacteria (or similar) into sugar.

In our world, sugars are held quite valuable by living systems, so this would be like throwing away fuel.

What kind of composition would these bacteria have to have chemically, and what kind of composition would their food have to have, for this to make sense in their (preferably not immediately dangerous to human) environment?

The organism should be able to excrete any form of sugar that is digestible to humans.

(Note that this is "Science Based" but doesn't have to be exact like "Hard Science")

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    $\begingroup$ Are you familiar with "bees"? Have your organisms make basically honey for storage purposes. Just as a general note, questions such as "What kind of composition would these bacteria have to have chemically" are so complex that they should remain unanswerable for a couple hundred years more. $\endgroup$
    – Raditz_35
    May 11, 2018 at 12:24
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    $\begingroup$ @Raditz_35 to be fair, bees store honey in their own hives for their own consumption,, bees don’t just deposit honey in the environment for anyone to eat $\endgroup$
    – taylor swift
    May 11, 2018 at 12:32
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    $\begingroup$ Bees, and many fruits, store a lot of sugar for later use/offspring. I'm primarily wondering what kind of organisms would completely discard sugar. $\endgroup$
    – DoubleDouble
    May 11, 2018 at 12:33
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    $\begingroup$ @DoubleDouble Edit your question accordingly then. The answer would be "an organism that can't digest glucose (or whatever sugar)". Take for example en.wikipedia.org/wiki/Raffinose , that's a sugar that can't be digested by you. Perhaps the article will even answer your question, even though I still claim that it can't be really answered, you can only describe the issue and be more precise and use fancy words (see the wikipedia article) $\endgroup$
    – Raditz_35
    May 11, 2018 at 12:37
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    $\begingroup$ Just an aside note--lately I've been thinking about the way plants "Throw away" so much energy to create mass (Breaking Co2 into carbon and oxygen takes energy but they want to re-use the carbon to build hydrocarbons). I think that the free oxygen created by this process powers nearly every useful chemical reaction that happens on our planet including all other life. $\endgroup$
    – Bill K
    May 11, 2018 at 16:25

8 Answers 8

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Aphids excrete sugar. Maybe your creatures can do the same.

aphid exreting honeydew

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

Aphids secrete "honeydew": sugar rich secretions that fall onto your car and make a sticky mess. This is good stuff with caloric value for humans and ants and other things too. https://en.wikipedia.org/wiki/Honeydew_(secretion)

Why would the aphids forgo energy? It is energy for them as well. It is because there is so much. The aphids need to process a lot of the protein-poor sap to get enough protein for themselves. With that sap is more sugar than they can use, which makes it waste to be excreted.

For your bacteria the issue needs to be carbon vs nitrogen. Carbon is energy and nitrogen is required for anabolic synthesis of tissues. If you have an excess of carbon you need to process it and get rid of it to obtain the associated nitrogen. Carbon-rich, nitrogen-poor environments are common on Earth and elsewhere. Outside of Earth, one circumstance where available nitrogen is bound up in a surfeit of carbon is tholins:

Tholins (after the Greek θολός (tholós) "hazy" or "muddy"; from the ancient Greek word meaning "sepia ink") are a wide variety of organic compounds formed by solar ultraviolet irradiation or cosmic rays from simple carbon-containing compounds such as carbon dioxide (CO2), methane (CH4) or ethane (C2H6), often in combination with nitrogen (N2). Tholins do not form naturally on modern-day Earth, but they are found in great abundance on the surface of icy bodies in the outer Solar System, and as reddish aerosols in the atmosphere of outer Solar System planets and moons.

Wave your hands now! Your tholin-dwelling bacteria extract their needed nitrogen from the excess of carbon by partly oxidizing the carbon, substituting oxygen for nitrogen. Freed from its carbon cage, the nitrogen is available to the bacteria for protein synthesis. The partly oxidized carbon is left as a nitrogenless but delicious waste product.

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    $\begingroup$ +1. Better than my answer, I'm afraid. $\endgroup$
    – Mołot
    May 11, 2018 at 13:06
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    $\begingroup$ +5 if I could for the educational purposes alone... $\endgroup$
    – WernerCD
    May 11, 2018 at 19:29
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    $\begingroup$ and poetic! Hal Clement, is that you, reincarnated? $\endgroup$
    – Spike0xff
    May 13, 2018 at 3:30
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Aspergillus oryzae also known as koji is a mold. It is capable of breaking starches and other polysaccarides into sugar. It does this for its own benefit, but actually produces more sugar than it can use itself.

Sugar however is a preservative and an antibiotic. If you can produce excess sugar, and you have evolved to tolerate elevated sugar levels you have an advantage over other organisms that might want to use a food source.

Koji will enter into a symbiotic relationship with yeast, the koji will produce sugar, the yeast will ferment the sugar into alcohol. Yeast and koji are tolerant of levels of sugar and alcohol that would be toxic for other microorganisms, so the koji and the yeast, united, can utilise food sources that they could not exploit alone.

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    $\begingroup$ Is it really symbiotic? What does the Koji get from the yeast? $\endgroup$
    – Tyler S. Loeper
    May 11, 2018 at 19:02
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    $\begingroup$ Toxic alcohol to poison competitors. I don't know if such a relationship exists in our world (this is a worldbuilding answer) but I know it exists between lactic acid bacteria and some yeasts. $\endgroup$
    – James K
    May 11, 2018 at 20:45
  • $\begingroup$ @TylerS.Loeper Toxic alcohol to poison other bacteria and the removal of equally poisonous monosaccharides. $\endgroup$
    – The Daleks stand with Ukraine
    Sep 7, 2020 at 22:09
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Ants and aphids

Aphids "are small sap-sucking insects and members of the superfamily Aphidoidea" (Wikipedia). They live on plants and feed passively by tapping the elaborated sap, which is basically a solution of sugars in water, flowing trough the plant host. They don't use all the sap they take, and excrete the excess in the form of honeydew, which is a concentrated solution of sugar.

Some species of ants farm aphids; the ants take care of the aphids and protect them, and feed on the "honeydew the aphids release from the terminations of their alimentary canals" (Wikipedia).

An ant guards its aphids An ant extracting honeydew from an aphid

Left: an ant guards it aphids; photograph by Agrinberg, available on Wikimedia under the CC BY-2.0 license. Right: an ant extracting honeydew from an aphid; photograph by Jmalik, available on Wikimedia under the CC BY-SA-3.0 license.

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There is a massive difference between a creature that consumes sugar and discards what it cannot process vs a creature that releases sugar as a waste material. If that difference is irrelevant to you, then aphids!

From an energy perspective, sugar is a poor material to excrete as a waste material because it is high energy density. It is a good energy store.

You would have to hypothesize a biochemisty that uses a chemical that has a higher energy density than sugar, but then breaks down into sugar as the energy is extracted and excreted as waste. This would likely include an environment so rich in high-energy density material that excreting sugar as waste would have been evolutionary viable.

Maybe Gasoline could be a naturally occurring and highly abundant material. This would require a chemist to verify if its realistic.

Perhaps the single-celled organisms that evolved to become multi-celled beings managed to harness nuclear radiation and therefore organic chemicals just gunk up their 'digestive' system. Basically they consume food for the amino acids and maybe lipids, but the carbohydrates are just excreted as waste. Good luck explaining how the cells would be protected from the radiation though, that would be an entirely different WB question.

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Aspergillus oryzae (koji)

Look up Aspergillus oryzae. It is a member of a very abundant group of molds Aspergillus and this microorganism actually creates simple sugars from complex carbohydrates. So I think it works well with what you are looking for. It is not a bacteria, but I guess the gene clusters could be transferred from these fungal organisms to bacteria, if needed. As far as "non carbon based" goes, however, I think it is not compatible with the very nature of what sugars are! (basically carbon chains).

I don't know if they "discard" the sugars, per se, but they clearly don't use them. Indeed, in the process of making saké, there are two "fermentation steps". The first "fermentation" is done with koji, which is a starter culture of Aspergillus oryzae. I use quotations for "fermentation" as it is in fact a saccharification process. And the koji molds don't use the fermentable sugars, because the actual fermentation is done in a separate step (meaning the sugars have accumulated in the culture medium, before the actual fermentation).

The actual fermentation is done, of course, with a strain of the classical wine yeast saccharomyces that use those sugars and converts them to alcohol. Yeast can not use complex sugars to produce alcohol, which means that Aspergillus oryzae produce true simple sugars.

Considering that saké are usually very high in alcohol (commonly 12-15% abv) and that fermentation is not sustainable above 15% abv (for most yeast), it means that they have access to large amounts of fermentable sugars generated during the koji "fermentation".

So these Aspergillus guys use complex carbohydrates as source of food (like starch of cellulose) and output simple sugars. They are also used for the preparation of certain foods.

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Many bacteria do excrete sugars in the form of exopolysaccharides in biofilms, so bacteria do excrete sugar molecues in the wild. Maybe combining this with the raffinose comment above, you could imagine a world where bacteria can manufacture both D and L glucose but organisms can't digest D glucose, so that bacterial biofilms on this world contain a lot of D glucose (or a polysaccharide the easily breaks down into D glucose).

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Edit: this answer is actually better, but I believe mine still provides usable solution.

There is no sense to discard sugar

Not with biology and biochemistry as we know it. Sugar is readily available energy source. metabolic pathways to extract that energy, with or without use oxygen, are really old and relatively short.

Discarding energy makes no evolutionary sense. Evolution generally minimizes energy spent. Gathering energy just to throw it away gives no benefit, using it for growth and procreation will always be preferred.

How it might evolve?

The only reason do "discard" sugar that makes sense, is to store it for future use. Bees do exactly this. Carrots and potatoes do similar thing (store internally). There is no reason for bacteria / yeast / algae biofilms and other colonies not to evolve this trait, if food is available for them for some time, and hunger is regular. If conditions change and food will always be plentiful, they will store it, and store, and store, and never use it.

This will not be stable. Evolution will get rid of this trait, probably rather soon. But in the narrow window between environmental change and evolution catch-up, you can have your microorganisms appear to work as you want them to.

Composition of microorganisms and their food

Actually, it will be really similar to composition of microorganisms now, and their food. Metabolic pathways to create glucose exists. There just need to be a reason for them to be used in this specific way.

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    $\begingroup$ I've already pointed that out in the comments, but I'm gonna point that out again: We discard a lot of potential energy that's sugar-based, take cellulose, chitin or my example of raffinose. $\endgroup$
    – Raditz_35
    May 11, 2018 at 13:18
  • $\begingroup$ @Raditz_35 none of it is really digestible to humans, right? So out of the question. And everything humans can use, microorganisms also can. And we do not excrete it, we just do not absorb it. In case of humans, reason (or as close to reason as we can say talking evolution) was that developing / keeping metabolic pathways for these was more energy-intensive than it was worth. byt when we really do excrete sugar, in sweat or with piss, it means we are ill, usually seriously. $\endgroup$
    – Mołot
    May 11, 2018 at 13:26
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    $\begingroup$ Aphids discard sugar. $\endgroup$
    – Mermaker
    May 11, 2018 at 13:55
  • $\begingroup$ If a microorganism for example never has access to some random sugar, there is absolutely no reason for it to produce the necessary proteins to digest it. I don't think you can have " everything humans can use, microorganisms also can" as a universal rule. I don't know if this is actually the case, but there is no real reason for this to be true, one can even quite easily create such a microorganism in a lab I assume with current technology $\endgroup$
    – Raditz_35
    May 11, 2018 at 14:05
  • $\begingroup$ @Raditz_35 Some humans can't even properly digest lactose, which is a sugar. $\endgroup$
    – fyrepenguin
    May 12, 2018 at 1:02
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Why not photsynthetic algae or plankton?

Algae and plankton use UV radiation while capturing CO2 from the atmosphere to bind and create sugar and some more complex variants of it to use as food. If in your world there has been a recent raise in CO2 concentration(would also rise water acidity) or a rise on radiation levels, these organisms could be on a superreproductive/high activity phase.

This would mean that they would be constantly producing more of those sugars than they need while also multiplicating rapidly. The high concentration of sugar inside them would mean that a part of it would end up filtering out into the environment (these beings usually live in water, so you would end up with sugary water). If it is not released at enough speed, some of these beings would/could end up dying with sugar intoxication. After death, the membrane of these beings usually ruptures, releasing the sugar and other chemicals.

This would even allow you to have people carrying containers of water mixed with these organisms to have them produce sustenance when needed by exposing them to the air and sun.

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