Mold culture plate (C) Daniel FriedmanMold Identification Photographs of Mold Growing on Petri Dishes or Mold Culture Plates or Settlement Plates
     


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Photographs of mold culture test kit results: this article illustrates common results of mold test kits that use a culture medium, and along with several companion articles listed here, it explains the availability and usefulness of eye-level or low-power magnification photographs of mold growing on mold culture plates, settlement plates, and mold test kits to try to identify indoor mold contamination.

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Mold Photos in Petri Dishes - Not so Useful for Environmental Sampling and Mold Identification - What Level of Magnification is Needed to Identify Mold?

Mold culture (C) Daniel FriedmanFollowing the list of some of our online guides to building mold just below, we include photographs of what mold looks like when growing on culture media commonly used in home test kits for mold.

In this article series we discuss the validity of nearly all of the popular mold testing methods currently in use, pointing out the strengths and weakness of each approach to mold sampling in the indoor environment, beginning with air sampling for airborne mold levels indoors.

The use, accuracy, and reliability of mold culture test kits for screening buildings for mold contamination are discussed at MOLD CULTURE TEST KIT VALIDITY and MOLD CULTURE SAMPLING METHOD Also see Mold Culture Plate Test Errors.

 

Mold Test Kit Culture Plates: Why Can't I Find More Photos of Mold in Petri Dishes?

Mold petri dish (C) Daniel FriedmanQuestion:

I was disappointed as there were no photos at all of petri dish examples of mold, and this is the way most of us out here will be testing for mold. So, how do I explore what mold I have in my petri dish test? I have quarter sized discs of black/dark green mold growing. I did the airborne mold test.

My dog is always coughing and I am in pretty good health but feel a slight "tug" in my breathing, a slight heaviness in my lungs but not bad. I rent my apartment and my landlord is a total tool.

What can I do financially and health wise to explore my situation? Thanks for any tips!!! - Tony K

Reply: Microscopic Examination of Mold is Necessary for Reliable Identification

By Eye Examination of Culture Plates or Petri Dishes to Identify Mold?

The short answer is that you cannot reliably identify what mold is found in a petri dish simply by looking at some photos or color charts. Some mold genera or species might be ruled "out" or "possible" but expert examination of the sample using high-powered microscopy (or another definitive method) is needed.

About what you can do about mold, take a look at MOLD / ENVIRONMENTAL EXPERT, HIRE ? - for help in deciding if your situation honestly merits hiring an expert. Then see MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD. If you are using mold culture plates, because mold test validity and mold test accuracy are often confused, see Cultures to "Test for Mold". Also see MOLD GROWTH on SURFACES for an index of what mold genera/species are frequently found on various building surfaces and materials.

Mold petri dish (C) Daniel Friedman

We do have some photos of mold in petri dishes posted just above and online, at other of our online articles about the role and limitations of using mold cultures as "home test kits" at Cultures to "Test for Mold". (You'll see there that what grows in culture is not necessarily the dominant or most significant mold that is present in a building.)

Traditionally, petri dish or culture plate photos were included in early mold taxonomy texts, where color and texture of mold growth at that scale assisted in identification of cultures of a known genera down to species level.

These were photos of mold cultured in laboratories where it is sometimes possible to separate a genera of mold (Aspergillus sp.) into species or groups of species (Aspergillus niger) based on color and other macro-characteristics.


Penicillium in culture (C) Daniel Friedman


In the closeup of a mold culture petri dish growth shown in our photo at above-right, high-powered microscopic examination was necessary to identify Penicillium sp (photo at left) as one of the several mold genera growing among these green, gray,and dark gray colored mold colonies.

Sometimes we can make a pretty good guess about mold identification by the naked eye, if we see a particular color and texture of mold on a particular surface. For example this photo of mold on an orange is showing what is most likely a species of Penicillium.

But in general that "by eye" mold identification approach is not reliable.

Stereoscopic Microscope Photos of Mold to Identify It?

Fuligo septic (C) Daniel Friedman

An "in-between" level of magnification, between using the naked eye to look at mold culture growing in a petri dish and using a high powered microscope is the use of a stereo microscope to magnify mold growth on surfaces such as on culture media in a petri dish.

For example, our stereoscopic microscopy photo of Fuligo septica (left) is characteristic of that particular fungus.

Stereoscopic mold photos are often beautiful (like this stereoscopic photo of Stemonitis mold growth structures taken in our lab) and may be helpful in identifying a mold genera. Here, for contrast, is a high power microscope photo of Stemonitis mold spores.

But stereoscopic magnification is inadequate for reliable mold identification.

High Powered Microscopic Identification of Mold Spores

Fuligo septic  (C) Daniel Friedman


For environmental samples in which we need to identify mold genera/species or other particles, it's a different story.

As we operate a forensic lab that processes lots of materials including mold, collected by various means, we see that while petri dish photos are pretty, they are not diagnostic, nor can they be used alone for mold identification at that scale.

We need to examine mold structures and spores at 300x to 1200x to actually identify genera/species reliably. See MOLD by MICROSCOPE for examples.

The Fuligo septica mold spores in our photo provide very different information than what we can get by eye looking at a mold culture plate or petri dish.

Also see more photos at MOLD ATLAS & PARTICLES INDEX and our Alphabetic Index to Mold Genera or Species

At MOLD "TESTING" vs. MOLD "PROBLEM IDENTIFICATION" we discuss the question of what sorts of mold testing are most useful and which are actually diagnostic, giving information about the presence of a mold problem with enough information that you know what to do about it.

Additional Comments on Mold Culture Identification

Mold cultures involve the collection of particles by air sampling pump, by gravity settlement, or by lift from a surface using a swab or tape. Some sampling equipment (Anderson™ spore traps) can collect spores directly into a petri dish of culture medium, and are used for "viable spore sampling in air."

Mold Culturing is useful for genera speciation once you have collected a single or dominant sample whose importance (frequency in the building) you already know. As a "home test kit" for the presence of problematic mold in a building this is an unreliable method, as we describe below at "shortcomings."

Mold culture (C) Daniel Friedman Mold culture (C) Daniel Friedman

Our lab photo (above left) shows two different mold colonies growing on a culture plate where individual spores settled out of the air onto this surface.




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