So obviously anything with sugars will ferment if left out, and since mushrooms metabolize stuff, I'm assuming they create and store sugars, even if at very low concentrations.

What are the considerations needed for fermenting, and distilling, ethanol from fungal crops - or any organism that does not require light (it can require imported material from a lit environment, e.g. livestock). What are the candidate sources of sugar for fermentation, the special adaptations required to traditional brewing/distilling, and what sorts of flavor profiles (or what are the determinants thereof) would one reasonably expect from these?

  • 3
    $\begingroup$ Yeast is a fungus. It doesn't produce sugars, it metabolizes them and produces alcohol and carbon dioxide. Producing and storing sugars is done by photosynthetic plants. $\endgroup$
    – Zeiss Ikon
    Jul 22, 2021 at 19:07
  • $\begingroup$ Does that mean that basically anything that lives out of sunlight can't be fermented at all? $\endgroup$ Jul 22, 2021 at 19:26
  • $\begingroup$ I'm no mycologist, but where would such organisms get energy to produce sugars? Without photosynthesis, there is only consumption (incomplete, as with yeast, or more complete as with animals. $\endgroup$
    – Zeiss Ikon
    Jul 22, 2021 at 19:36
  • $\begingroup$ Yeah, that's one of the things I'm asking here, by implication. Given that 'Mushroom Beer' is a trope for fantasy Dwarven cultures and the like (Dwarf Fortress holds that one makes wine, not beer, out of mushrooms), I'm trying to figure out what the ecology/agriculture cycle of that looks like. $\endgroup$ Jul 22, 2021 at 19:38
  • $\begingroup$ I always figured the Dwarves traded for grain, and used mushrooms in place of hops or gruit to flavor the beer. $\endgroup$
    – Zeiss Ikon
    Jul 22, 2021 at 19:40

3 Answers 3


Mushrooms instead of Yeast:

I like rek's very thorough answer, but I think we're getting bogged down in semantics about where the sugar source is. Fundamentally, since fungus needs food to grow, any fungus crop needs an energy source from something. If you produce fungus, it grows on SOMETHING that has energy. Where does that energy come from? Biomass.

A mushroom isn't that different from yeast. Under the right conditions, it can convert a carbon and energy source to ethanol. You just need the right enzymes (which you have). If you find one that does so, and selectively breed a mushroom to store excess ethanol, You have a drunken mushroom. You skip the fermentation step (which the mushroom does) and go straight to extraction and/or distillation. You could probably even eat the raw mushroom and potentially get drunk. No need for a brewer, although you could probably produce a more concentrated beverage by crushing or distilling.

Mushrooms bred this way could potentially produce ethanol from anything the mushrooms could grow on, although something with sugars/saccharides makes a lot more sense. Almost any plant material can provide saccharides (like cellulose). We're working today on getting yeast to turn low-quality biomass to various alcohols for fuel. But if the mushroom does what it does and is rewarded with humans/Dwarves supplying it with an endless source of biomass, it will succeed and continue to produce ethanol.

And if I go to a dwarven party and people wonder why EVERYONE wants the mushroom salad, I'll know why.


One example of polysaccarides occurring into fungi are beta-glucans

β-Glucans (beta-glucans) comprise a group of β-D-glucose polysaccharides naturally occurring in the cell walls of cereals, bacteria, and fungi, with significantly differing physicochemical properties dependent on source. Typically, β-glucans form a linear backbone with 1–3 β-glycosidic bonds but vary with respect to molecular mass, solubility, viscosity, branching structure, and gelation properties, causing diverse physiological effects in animals.

Glucans are arranged in six-sided D-glucose rings connected linearly at varying carbon positions depending on the source, although most commonly β-glucans include a 1-3 glycosidic link in their backbone.

Converting them to alcohol is a matter of having the right enzyme, not that different from being able to digest cellulose or not.

  • $\begingroup$ Do I correctly infer thereby that any deliberate fermentation at-scale would follow the basic chemistry of cellulosic ethanol? Or is that a whole different thing? $\endgroup$ Jul 22, 2021 at 19:39
  • $\begingroup$ @WilliamWalkerIII, the atoms are all there, they need to be properly rearranged $\endgroup$
    – L.Dutch
    Jul 22, 2021 at 19:42
  • $\begingroup$ So my understanding of cellulosic ethanol is that there's two methods, the syngas method, which seems entirely too high-tech for primitive techbase, but viable for advanced - which essentially skips the fermentation entirely and goes directly to distilled alcohol -- or the biochemical method which involves acid and then hydrolysis, a sort of cracking process AIUI, which could be done by anyone who has vinegar and heat. The resulting product of that is an unknown to me and part of what I'm interested in, what's that feedstock like for fermentation, what are its dominant flavors, etc? $\endgroup$ Jul 22, 2021 at 19:46

Both papers I could find on this subject required a sugar source (presumably allowed per 'imported material from a lit environment') but made use of mushrooms to convert it to alcohol:

Characteristics of wine produced by mushroom fermentation -- T Okamura et al. Biosci Biotechnol Biochem. 2001:

Saccharomyces cerevisiae is the main microorganism used in wine brewing, because this microbe has potent ability to produce alcohol dehydrogenase. We have recently discovered that some genera of mushroom produced alcohol dehydrogenase, and made wine by using a mushroom in place of S. cerevisiae. The highest alcohol concentration in this wine was achieved with Pleurotus ostreatus (2.6 M, 12.2%). In the case of Agaricus blazei, the same alcohol concentration (1.7 M, 8%) was produced under both aerobic and anaerobic conditions. This wine produced by A. blazei contained about 0.68% beta-D-glucan, which is known to have a preventive effects against cancer. The wine made by using Flammulina velutipes showed thrombosis-preventing activity, giving a prolonged thrombin clotting time 2.2-fold that of the control. Thus, the wine made by using mushroom seems to be a functional food which can be expected to have preventive effects against cancer and thrombosis.

The paper is available for free here.

Ethanol Production from Various Sugars and Cellulosic Biomass by White Rot Fungus Lenzites betulinus -- Kyung Hoan Im et al. Mycobiology. 2016 :

Lenzites betulinus, known as gilled polypore belongs to Basidiomycota was isolated from fruiting body on broadleaf dead trees. It was found that the mycelia of white rot fungus Lenzites betulinus IUM 5468 produced ethanol from various sugars, including glucose, mannose, galactose, and cellobiose with a yield of 0.38, 0.26, 0.07, and 0.26 g of ethanol per gram of sugar consumed, respectively. This fungus relatively exhibited a good ethanol production from xylose at 0.26 g of ethanol per gram of sugar consumed. However, the ethanol conversion rate of arabinose was relatively low (at 0.07 g of ethanol per gram sugar). L. betulinus was capable of producing ethanol directly from rice straw and corn stalks at 0.22 g and 0.16 g of ethanol per gram of substrates, respectively, when this fungus was cultured in a basal medium containing 20 g/L rice straw or corn stalks. These results indicate that L. betulinus can produce ethanol efficiently from glucose, mannose, and cellobiose and produce ethanol very poorly from galactose and arabinose. Therefore, it is suggested that this fungus can ferment ethanol from various sugars and hydrolyze cellulosic materials to sugars and convert them to ethanol simultaneously.

An alcohol produced directly or solely from the mushroom does not appear to be all that feasible due to very low carbohydrates in mushrooms: less than 4g per 100g (most lower), compared to 15g and up for grapes, corn (~25g), and wheat (~75g), as I'm seeing across various nutrition sites.


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