What does mold look like under the microscope? These mold spores and their photographs (both on site and under the microscope) have been collected in the U.S., Spain, Mexico, France, as well as in other countries. These are aerobiology laboratory photos of mold under the microscope.
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In this article we provide lab photographs of mold under the microscope.
The photo at page top shows Stachybotrys chartarum mold spores under the microscope, and next to them is a photo of the Stachybotrys spore-producing structure or conidiophore.
Other photographs and articles at this website will help you find and recognize problematic toxic or allergenic mold in buildings.
Nearly all of our mold spore photographs shown at this mold spore identification assistance page are from field samples collected in buildings.
What makes these photographs helpful is that they are "real world" examples of mold spore occurrence, including the surrounding debris and sometimes rough growth patterns of mold spores that occur in situ in buildings.
Mold grown in the laboratory or on cultures is often very crisp, beautiful, and perhaps more easy to identify. But the actual physical structures of mold growth for a given genera and species may vary significantly depending on the material on which the mold is growing - its food. Photographs of mold spores under the microscope shown here are in that sense, more "natural" than those obtained from culture.
Photographs of Mold Under the Microscope
Mold spore photographs are arranged alphabetically here. For example, if you are looking for what Stachybotrys chartarum spores and growth structures or conidiophores look like under the microscope, just scroll down to the "S" section of our identification photographs of mold under the microscope.
Index to Building Mold Genera/Species in This Document
Acremonium like Mold Spore Photographs
Here is a laboratory microscopic photograph of Acremonium like mold growth found on wet "fuzzy" basement vinyl flooring and at a water heater leak in Missouri.
Agrocybe sp. mold spore photographs
Photograph of an Agrocybe spore (see Basidiomycetes). Individual Agrocybe spores are common in outdoor air samples collected with spore traps.
The photograph of Alternaria spores in a cluster (above left) shows these spores with their proper coloration. The Alternaria sp. photograph at above right demonstrates the confusion in spore coloration and thus in spore identification that can occur when a novice microscopist relies too heavily on fuchsin stains for spore detection.
Alternaria mold spores are very common in outdoor air and are likely to be found in outdoor air samples and are often found in indoor air samples as well. Growing on a building surface (or in culture) Alternaria sp. will also appear in spore chains (photo at left) and attached to fungal hyphae.
Our Alternaria sp. mold spore chain photo (left) also includes skin flakes and at bottom center an Ascomycete.
Comparing the Alternaria spores to the human skin cells and to the smaller Ascomycete you can see that Alternaria fungal spores are quite large among members of the Fifth Kingdom.
Arthrinium sp. mold spore photographs
Arthrinium fungal spores (in close-up at 1200x) form group of at least twenty species, some of which are ovate or lemon-shaped. Possible examples of A. phaeospermum are shown below. This fungus is often confused with the ubiquitous Chaetomium sp. fungal spore when the latter is not fully hydrated. Look for not a fold in the spore (dessicated) but a hyaline band at the junction of the two sides, and look for the birth scar (bottom of the spore at below right) - that's an Arthrinium sp. spore not Chaetomium sp. [Thanks our instructors, mycologists Dr. Harriet Burge and Dr. John Haines.]
Chaetomium sp. is an Ascomycete, born in groups of 8, and without a birth scar as it emerges from a perethicium not by growing on a fungal hypha. And the center fold on Arthrinium will extend pretty much to the ends of the spore.
Aspergillus sp. mold spore photographs
Photographs of Aspergillus sp. mold spores under the microscope Aspergillus niger culture, Penicillium culture, Penicillium spores - Aspergillus and Penicillium spores are difficult to differentiate when they are found in air that you may see them reported in test results as "Pen/Asp".
Watch out: Most Pen/Asp spores are round, hyaline (colorless) and small and lack surface features to aid in their precise identification by microscope when the spores are found alone, or in air samples (and if not in spore chains). In that case the spores may not even be identified as (potentially harmful) molds and may just be called "amerospores" in the lab report.
But when these spores appear in chains (as that's how they are born) they should not be labeled as "amerospores", and at least some of these airborne spores in the Aspergillus/Penicillium group can be identified from the spore alone, however, such as Aspergillus niger
Also see our lab photographs of dense surface growth of Aspergillus niger and Aspergillus fumigatus side by side, in the same surface sample, but not quite intermixed.
We find lots of the fungus spores shown above, Aureobasidium pullulans, a black yeast fungus, growing on wet or damp wood in buildings, especially on plywood roof sheathing in poorly-vented building attics.
This yeast-like fungus is also often found on caulk or damp window frames in bathrooms. Aureobasidium may be pink or black in color. More detail is at MOLD ATLAS & PARTICLES INDEX. And we discuss this mold further at Recognize Harmless Black Mold.
Biolaris-Drechslera sp. mold spore photographs
Lab microscopic photographs of an Bipolaris-Drechslera spores are provided below. In lab reports Bipolaris sp. and Drechslera sp. fungal spores are often grouped together as a class because of physical similarity.
Ceratocystis/Ophistoma - the Ophistomoid Cosmetic Black Sapstain or Bluestain Molds on Lumber
Laboratory microscopic photographs of Ceratocystis/Ophistoma type mold are a bit tricky in surface samples such as collected from moldy lumber, because usually this mold is dry, often encysted, and because it is not likely to be growing on an indoor surface, the sample may lack clear identifying particles or structures.
Here at above right we show a sketch of the perithecium, ascospores, and conidia of Endoconodiphora coerulescens from the July-August 1953 issue of Mycologia Vol XLV No. 4.
Our photograph at above left shows a fungus found under a basement stairwell that we classified as Ceratocystis/Ophistoma, and in this photograph you can see an enlarged closeup of mold fragments from that sample.
Watch out: Because this dark colored fungal growth appears "black" on wood surfaces, scaring some folks into unnecessary and costly "toxic black mold remediation" projects, we discuss the cosmetic Ceratocystis/Ophistoma mold group in detail at Recognize Harmless Black Mold.
Lab microscopic photographs of an Chaetomium spores: Chaetomium sp. (C. globosum, C. aureum, and others) are very common indoor molds found especially where drywall or other paper covered products have been wet.
Chaetomium sp. (photo below left) is an Ascomycete and is ubiquitous in water damaged buildings, especially on drywall paper. We find Chaetomium fungal growth often co-existing with Stachybotrys sp./ S. chartarum (photo below right - the S. chartarum are the ovate black spores) Where Chaetomium mold growth has been found indoors in spore clusters like this it is probably appropriate to investigate the building leak history and to remain alert for the presence of other indoor mold reservoirs.
Watch out: What Chaetomium fungal spores look like in the microscope depends a lot on how they are prepared (what mountant chemicals) and the extent of spore hydration. So Chaetomium that is not well hydrated remains "folded" to produce a center furrow that can cause it to be mistaken for Arthrinium sp. (a mistake we see in Grant Smith's execllent book of mold photos) and other molds.
Our Chaetomiium sp. photo at below left illustrates both hydrated and under-hydrated spores. At below right we see a close-up of a few Chaetomium spores at 1200x via our Polam microscope.
Cladosporium sp. mold spore photographs
Microscope photographs of Cladosporium sp.: Cladosporium sp. are the most common mold spore found in outdoor air in many areas, so common in fact that Cladosporium is called "the king of molds". The photograph of Cladosporium sp. spores in a cluster (above left) shows these spores with their proper coloration.
The Cladosporium sp. photograph at above right demonstrates the confusion in spore coloration and thus in spore identification that can occur when a novice microscopist relies too heavily on fuchsin stains for spore detection. However both photographs show the characteristic dark scars at the attachment point for these mold spores.
Our photograph at left shows the dominant spherical spores produced by Cladosporium sphaerospermum - another common indoor and attic/roof-sheathing mold.
Curvularia sp. mold spore photographs
Curvularia mold spores at above left may not be looking their best in this field photo but this is what you're likely to see at the microscope. The Curvularia sp. at above right was in better condition, showing its attachment scar as well.
Drechslera sp. mold spore photographs
Microscope photographs of Drechslera sp. fungal spores - under the microscope Drechslera and Bipolaris mold spores are both large, segmented spores such as the member shown here, and may require additional careful examination to differentiate the two.
Epicoccum sp. mold spore photographs
Microscope photographs of Epicoccum sp. (E. niger)fungal spores under the microscope are large, segmented spores such as the member shown here.
Fuglio septica mold & mold spore spore photographs
Fuglio septica is shown under the stereoscopic microscope (less than 100x) at above left, while Fuglio septica mold spores are shown at above right. This fungus is affectionately called "dog vomit mold" by some field investigators as when found growing outdoors on bark chips that's about what it looks like. We do not normally find this mold growing indoors.
Ganoderma sp. mold spore photographs
Microscope photographs of Ganoderma basidiospores such as G. applanatum & G. tsuge dominated the air at a recent fungal spore study workshop sponsored by the University of Montreal. Here is where they were coming from.
Gonadobotryum mold spore microphotographs
Here are microscopoic photographs of Gonadobotryum sp. mold collected during a building investigation. We often find Gonadobotryum sp. mold growth present as a parasite, growing on top of other fungi, especially in the Ceratocystis/Ophistoma group on framing lumber.
The presence of Gonadobotryum sp. mold on framing lumber is probably not a health concern; it has not been reported as producing mycotoxins but we would not rule out its possible role as an allergen.
Meruliporia Incrassata - "Poria" "House Eating Fungus" Mold Microphotographs
Here are microscopoic photographs of Meruliporia incrassata mold spores collected in a building where extensive structural rot was found and "yellow mold" was visible on some of the rotting lumber.
We discuss this fungus in more detail at Meruliporia Mold Photographs.
Nigrospora sp. mold spore photographs
Nigrospora sp. mold spores are often round, smooth, and black under the microscope.
It is useful to check out black round "spores" under the microscope using top lighting in order to distinguish them from paint droplets where paint has been sprayed in the building. If the round spherical objects are all smooth but their size varies, or if toplighting shows that the "spores" are white or some other color, you're probably looking at spray paint droplets, not Nigrospora sp. mold spores.
Oidium (Mildew) sp. mold spore photographs
Oidium sp. is one of the most common appearances of the sub-group of molds in the mildew family.
This mold is often found in outdoor air. We do not normally find mildew growing on any indoor surface in buildings because the mildews are obligate parasites - growing only on living plants.
These spores are easy to identify by their color (none or hyaline), and their shape as well as their cellular inclusions or surface decorations visible in any sharply focused microscope at 400x or higher.
Penicillium sp. mold spore photographs
Penicillium sp. mold spores are very easy to identify when their spore producing conidiophores are collected in a surface sample (photograph at left).
But individual Penicillium sp. spores found in air or dust samples are difficult to distinguish (visually) from many Aspergillus spores as well as some other genera/species including some mold spores from a very different group, the Basidiomycetes.
A lab report of the presence of Amerospores (a generic name for unidentified small round colorless un featured spores) should not be assumed to have detected Penicillium sp.
Periconia sp. mold spore photographs
Periconia sp. mold spores are common at low levels in both indoor and outdoor air and dust samples.
Phoma sp. mold spore photographs
Phoma sp. mold spores are sometimes found indoors on building surfaces where leaks and rot damage are present.
Puffball mold spore photographs
Puffball mold spores (Basidiomycetes) are common in outdoor air samples in some seasons.
The spores are easily distinguished by their little hyphal stem attachments making them look a lot like tiny balloons.
If you ever stomped on those brown dried fungal clumps (when you were a kid), sending clouds of brown dust into the air, these photos show what you were sending aloft.
Native americans used puffball spores for medicinal purposes as well, possibly as a clotting agent on wounds.
Smut spore photographs
Smut spores common in outdoor air samples, would be unusual indoors.
Stachybotrys sp. / Stachybotrys chartarum black mold spore photographs
Stachybotrys sp. "black mold" spore photographs under the microscope as well as on building surfaces are provided here.
Some other more common mold spores such as Penicillium and Aspergillus (see above) may cause illness or may be associated or aggravate with some types of asthma. Stachybotrys mold, in another form, Memnoniella echinata we've found to be particularly reactive even in small quantities. When found on building surfaces it should be removed.
Stemonitis mold & mold spore photographs
Stemonitis mold & photographs of stemonitis mold spores common growing indoors on wet oriented strand board.
Torula sp. mold spore micro-photographs
Torula sp. fungal spores are shown in this lab photograph taken through the microscope, probably Torula herbarum.
We often encounter this mold on wet moldy or rotted plywood subfloors in buildings.
Ulocladium mold spore micro-photographs
Ulocladium sp. is often confused with similar looking versions of Stemphylium sp. and with some species of Alternaria sp. particularly as immature Alternaria spores can look like the simpler ovate cross-septated Ulocladium chartarum. And worse there are species of Ulocladium (U. alternariae - cf Ellis) that look like (and are even named after Altenaria sp.).
The differentiation between species of Alternaria and Ulocladium is not difficult once you've been instructed by a mycologist. The "tail" you see on the Alternaria-like mold spores still attached to hyphae (photo below right) comprises the attachment point for the spore to its hyphae. The "tail" on an Alternaria spore is at the opposite end of the mold from its attachment.
That is, an Alternaria spore is attached to its hyphae at its larger "head" end, not by its tail.
Ulocladium chartarum (below-left). Ulocladium sp. (below right).
Below are microphotographs of U. chartarum grown in culture by the author [DF].
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Frequently Asked Questions (FAQs)
May I know if I can spot on cloth and wonder if that is cause by mold, what would be the test charge with microscopy identification in your side? - Ann 5/11/11
If you are discussing mold on clothing or a cloth curtain, in my opinion it would not be economically justified to test it unless that test were necessary as part of a wider environmental investigation. The cost of testing a tape or vacuum sample of surface mold is typically $50. - which is more than the cost of having the item professionally cleaned or in some cases just replaced.
Question: can you see mold spores under a regular light microscope? What about cellular structures & nucleii?
if you were looking under a regular light microscope at fungus, would you see spores and would you see anything inside cell such as nucleus or would you need a more powerful microscope? - Alan 5/21/2012
Take a look at the mold spore photographs in the article above. The highest magnification we can use under most light microscopy is around 1200x, enough to see small spores down at the 1 micron level. In some cases of larger spores or more likely larger pollen grains, one can sometimes make out internal parts and components of an individual pollen grain or mold spore, but not the nucleus of an individual cell.
Our basement flooded during hurricane Irene in 2011. When we finally got power, we used a heavy industrial vac to remove the water from the basement. We moved everything into a dryer corner of the basement, and ran dehumidifiers. The entire basement seemed to dry within a matter of 2 days.
Reader further comment:\
I took pictures of the things that were precious to me; gave thanks and praise to God for the blessings that I had and still have, and then threw everything out!
At MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD we provide procedures for cleaning up a mold problem, and at EMERGENCY RESPONSE, IAQ, GAS, MOLD as well as at DISASTERS: BUILDING INSPECTION & REPAIR we describe procedures for handling building flooding following a hurricane, storm surge, sewer backup or similar problem.
At BOOK MOLD, CLEANING you can read about how we deal with books or papers that people want to save after flooding. Basically, if you have moldy papers that you need to save but cannot afford to clean, try drying them in sunlight (some folks try a microwave located outdoors), followed by gentle wiping and then store these modly items in a dry air-tight plastic box. The items will not have been cleaned and should not be handled without appropriate precautions, but they can at least be retained.
Thank you for the question.
Questions & answers or comments about what building mold looks at under the light microscope at magnifications from 10x to 1200x. .
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