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Guttation

Short answer: Guttation, the release of liquid droplets, is common across the fungal kingdom. How much a fungus produces depends heavily on conditions such as the growth medium and temperature, and its biological role is only partly understood.

Lab studies have found the droplets carry secondary metabolites and proteins. Penicillium expansum exudates held 20 specialized metabolites, including the mycotoxins patulin and citrinin, and 194 proteins. Droplets from ochratoxin-producing Penicillium strains held up to 11 times more ochratoxin A than the mycelium beneath them. Toxigenic Stachybotrys chartarum (black mold) produced droplets with up to several thousand nanograms of satratoxins per milliliter. Enzymes such as β-glucosidase, catalase and peroxidase have been measured in the exudates of plant-pathogenic fungi.

VideoWrite-up5 sources
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What should you know about Guttation?

Quick facts. Each one stands alone and has a stable ID you can cite.

  1. Guttation droplets from some Penicillium molds hold far more ochratoxin A than the mycelium that produces them, up to 11 times more.

    DD-064-F01 · Write-up · Exhibit C (Concentrated toxins)

  2. Toxigenic black mold (Stachybotrys chartarum) can produce guttation droplets laden with satratoxins.

    DD-064-F02 · Write-up · Exhibit D (Black mold)

Video transcript: Guttation: Fungi That Sweat Droplets

DID YOU KNOW? Fungal guttation is the process where fungi excrete droplets of liquid from specialized structures or hyphal tips, often visible as tiny beads of moisture on the surface of fungal colonies. These droplets contain a mix of water, enzymes, secondary metabolites, and sometimes toxins, reflecting the fungus' metabolic activity. NOW YOU KNOW!

Burned-in captions, read frame by frame (see transcript.md) · 18.6s Reel ·

Video coming soonGuttation · Instagram Reel
Guttation: Fungi That Sweat Droplets Instagram Reel · · 18.6s

The write-up

Fungi that sweat droplets. The beads can carry enzymes, metabolites and sometimes mycotoxins.

  1. Exhibit A

    Common but not well understood

    Guttation is common across the fungal kingdom. How much a fungus produces depends heavily on conditions such as growth medium and temperature, and its biological role has been explored only partly.

  2. Exhibit B

    What's in the drops

    Researchers have found mycotoxins, antimicrobials, insecticidal and antiviral compounds, and proteins in fungal exudate droplets.

  3. Exhibit C

    Concentrated toxins

    In ochratoxin-producing Penicillium strains, droplets held 92.7–8,667 ng of ochratoxin A per milliliter. That was up to 11 times more than the mycelium beneath them and up to 176 times more than the agar.

  4. Exhibit D

    Black mold

    Fourteen of 15 Stachybotrys isolates produced droplets. In the toxigenic ones, the droplets held macrocyclic trichothecenes (satratoxins G and H) at up to several thousand nanograms per milliliter.

  5. Exhibit E

    Enzymes and proteins

    Penicillium expansum exudates contained 20 specialized metabolites, including patulin and citrinin, and 194 proteins, mostly involved in breaking down plant walls. Exudates of plant-pathogenic fungi show activity of enzymes such as β-glucosidase, catalase and peroxidase.

  6. Exhibit F

    A possible role

    In salt-tolerant Aspergillus versicolor strains from a former uranium-mining site, droplet formation was linked to tolerance of salt and metals. The droplets held about 2,900 detectable substances.

Questions people ask about Guttation

What does guttation intensity depend on most?

Its biological role is only partly understood.

Source: Write-up · Exhibit A (Common but not well understood) · Fungal guttation, a source of bioactive compounds, and its ecological role: a review (Biomolecules, 2021)

Which mycotoxin was concentrated in Penicillium droplets?

It reached up to 11 times the level in the mycelium.

Source: Write-up · Exhibit C (Concentrated toxins) · Fungal guttation, a source of bioactive compounds, and its ecological role: a review (Biomolecules, 2021); Guttation droplets of Penicillium nordicum and P. verrucosum contain high concentrations of ochratoxin A and B (Mycopathologia, 2007)

Which toxins were found in Stachybotrys droplets?

These are macrocyclic trichothecenes.

Source: Write-up · Exhibit D (Black mold) · Stachybotrys spp. and the guttation phenomenon (Mycotoxin Research, 2014, PubMed)

How many proteins were found in Penicillium expansum exudates?

Most were involved in breaking down plant walls.

Source: Write-up · Exhibit E (Enzymes and proteins) · Fungal guttation, a source of bioactive compounds, and its ecological role: a review (Biomolecules, 2021); Exudates secreted: Penicillium expansum's means of conquering the external environment (Postharvest Biology and Technology, 2025)

In Aspergillus versicolor, droplet formation was linked to what?

The strains came from a former uranium-mining site.

Source: Write-up · Exhibit F (A possible role) · Salt and metal tolerance involves formation of guttation droplets in species of the Aspergillus versicolor complex (PMC, 2022)

Test Your Knowledge

All quizzes →

5 questions, all from this case file. Answers are revealed instantly.

  1. What does guttation intensity depend on most?

    1. Moon phase
    2. Growth medium and temperature
    3. Spore color
    4. Sunlight only
    Show the answer

    Answer: B. Growth medium and temperature Its biological role is only partly understood. Source: Write-up · Exhibit A (Common but not well understood) · Fungal guttation, a source of bioactive compounds, and its ecological role: a review (Biomolecules, 2021)

  2. Which mycotoxin was concentrated in Penicillium droplets?

    1. Aflatoxin
    2. Ochratoxin A
    3. Ricin
    4. Botulinum
    Show the answer

    Answer: B. Ochratoxin A It reached up to 11 times the level in the mycelium. Source: Write-up · Exhibit C (Concentrated toxins) · Fungal guttation, a source of bioactive compounds, and its ecological role: a review (Biomolecules, 2021); Guttation droplets of Penicillium nordicum and P. verrucosum contain high concentrations of ochratoxin A and B (Mycopathologia, 2007)

  3. Which toxins were found in Stachybotrys droplets?

    1. Satratoxins
    2. Patulin only
    3. Cyanide
    4. Alcohol
    Show the answer

    Answer: A. Satratoxins These are macrocyclic trichothecenes. Source: Write-up · Exhibit D (Black mold) · Stachybotrys spp. and the guttation phenomenon (Mycotoxin Research, 2014, PubMed)

  4. How many proteins were found in Penicillium expansum exudates?

    1. 4
    2. 20
    3. 194
    4. 2,918
    Show the answer

    Answer: C. 194 Most were involved in breaking down plant walls. Source: Write-up · Exhibit E (Enzymes and proteins) · Fungal guttation, a source of bioactive compounds, and its ecological role: a review (Biomolecules, 2021); Exudates secreted: Penicillium expansum's means of conquering the external environment (Postharvest Biology and Technology, 2025)

  5. In Aspergillus versicolor, droplet formation was linked to what?

    1. Light production
    2. Salt and metal tolerance
    3. Spore dispersal by wind
    4. Freezing
    Show the answer

    Answer: B. Salt and metal tolerance The strains came from a former uranium-mining site. Source: Write-up · Exhibit F (A possible role) · Salt and metal tolerance involves formation of guttation droplets in species of the Aspergillus versicolor complex (PMC, 2022)

Cite this case file

Easterling, Marcus. "Guttation." The Detail Department (DetailEnjoyer), case file DD-064, last updated Aug 3, 2025. https://detailenjoyer.com/case/guttation/

Permalink: https://detailenjoyer.com/case/guttation/ · Last updated

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