Mycelium metabolites or mushroom pee
Yellow liquid on mushroom mycelium: contamination or normal fungal reaction?
Sometimes you can observe healthy mycelium with small amounts of clear orange, yellow or brown liquid forming on the surface of the mycelium.
It can be noticed in spawn jars during colonization period.
It can be noticed on mushroom cake during casing layer colonization or fruiting period.
What is it? Is it something to be wary of?
What is Secondary Metabolites?
Secondary metabolites (aka mushroom exudate, mushroom urea, mushroom piss) — it is a waste products of fungal metabolism or mushroom exudate.
🔬 Biochemical analyses of the exudates showed that acid phosphatase, β-glucosidase, acid and alkaline protease, RNase polygalacturonase and cellulase enzymes as well as oxalic acid and ammonia were present.
In short and simpler they consist of acids, exopolysaccharides, waste products and antibiotics, which are naturally secreted by mycelium cells.
Often they can be found on different kind of mushrooms: wild mushrooms, magic mushrooms and various edible mushrooms.
Metabolites are natural immune response of the mycelium to stress or pathogens.
How to determine metabolites?
✅ Liquid is transparent.
✅ WITHOUT slime.
✅ WITHOUT odor.
✅ Color: yellow, orange or brown.
Mycelium Metabolites or Wet Bubble
If mycelium ingests excess of anything that may become toxic enough to eventually harm, disable or kill it, mycelium produces waste exopolysaccharides, acids, excrete enzymes and tries rid itself off that excess.
Metabolites are a reaction to stress or response to contamination (especially bacteria). Mushroom urea often accompanied overlay.
Metabolites (or exudate) is a natural mushroom antibiotic and immunity reaction. It’s not contamination itself. But it means that your mycelium struggles with pathogen microorganisms or stress.
🔴 Newbie cultivators often confuse secondary Metabolites with Mycogon aka Wet Bubble contamination.
It seems similar to metabolites, but it has its specific features (an amber liquid with a rotten smell oozes from primordia and clots of mycelium).
Main causes of mycelium metabolites
Metabolites are a reaction to:
🆘 lack of fresh air exchange
🆘 direct sunlight
🆘 high temperature
🆘 lack or excess of nutrients in the substrate
🆘 mycelium tissue damage
🆘 a symptom that mycelium is fighting with pathogenic microorganisms
🆘 this also happens if you mix several strains of mushrooms and they struggle between each other
🆘 a signal that mycelium is fighting pathogenic microorganisms
🆘 appear with stroma and overlay
Check out Fruiting conditions. Pinhead initiation. Growing parameters for Psilocybe Cubensis to adjust microclimate.
If mushroom mycelium struggles with contaminants, such mushroom cake requires close attention. Very often mycelium copes with mild contamination successfully. However, if slime and/or odor appears, such mushroom cake or spawn jar should be disposed immediately.
Occasionally, snow-white mycelium can turn beige, yellow or even brown during colonization period in the jar or during fruiting period in the growbox. It is also a kind of fungus exudate — waste products of mycelium.
This case can be as a reaction of fungal immunity to a minor contamination. It means mycelium struggles successfully! Observe and be attentive.
Minor pigmentation is very common in mushroom growing and nothing to worry about!
🔴 Newbie cultivators confuse pigmentation with Aspergillus yellow spp. (Aspergillus flavus)
Check out our full guide of all possible contaminants at all stages of mushroom cultivation in How To Recognize whether Mushrooms Contaminated or Not section.
Have a Happy Growing and Healthy Shrooms 🙏