Mold Identification Photographs of Mold Growing on Petri Dishes or Mold Culture Plates or Settlement Plates InspectAPedia® -
Can photos provide reliable identification of mold on culture plates or petri dishes?
Limitations of mold cultures as a "mold test kit"
Usefulness of culturing for the identification and study of mold
90% error rate in capture of mold genera/species with some mold test methods
Do all molds grow on culture?
Do all mold spores settle out of air at the same rate onto culture plates?
Are all mold spores equally important in mold samples?
Questions & answers about culture tests for mold contamination
This article 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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In this article series 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. Because mold test validity and mold test accuracy are often confused, readers should see Cultures to "Test for Mold". Also see ACCURACY OF VARIOUS MOLD TEST METHODS. People who need to conduct mold inspection and testing indoors should see MOLD TEST PROCEDURES and TECHNICAL & LAB PROCEDURES.
At MOLD BY MICROSCOPE we provide lab photographs of mold under the microscope. A more extensive library of mold and particle identification pictures is at MOLD ATLAS & PARTICLES INDEX where we include a discussion of the characteristics and health concerns for specific molds. Photographs of mold in culture plates or petri dishes are at MOLD in the PETRI DISH, PHOTOS.
Mold Photos in Petri Dishes - Not so Useful for Environmental Sampling and Mold Identification - What Level of Magnification is Needed to Identify Mold?
Why Can't I Find More Photos of Mold in Petri Dishes?
Question:
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 EXPERT, WHEN TO 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.
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.
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?
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
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 septic 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.
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."
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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Additional technical contributors & reference sources for this article are listed below.
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Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com
Thanks to Tony K for discussing mold in petri dishes and indoor sampling or mold testing using cultures - July 2010.
MOLD ATLAS & PARTICLES INDEX, Pathogens, Allergens and Other Indoor Particles - actual and possible medical health effects of Mold (separate online document)
MOLD GROWTH ON SURFACES, PHOTOS Photos of what mold looks like in buildings, organized by mold growth on various kinds of building surfaces and contents or items found in buildings. Mold in situ. MOLD GROWTH on SURFACES, TABLE OF, Summary table of what mold genera/species are frequently found on various building surfaces and materials
MOLD BY MICROSCOPE Mold under the microscope - photo identification of the most common indoor molds found in buildings
Contact Us to suggest changes and additions to these online mold identification guides
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
Looking for Mold Procedure: what mold is often found where in buildings - simple technical presentation
How to Look For Mold, List of Articles: Hiring a Mold or IAQ Consultant, Getting a Remediation Plan
Recognizing Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
Stuff that is not mold but is often mistaken for it - things you may not want to test. Also, not all "black mold" is toxic - here are examples of harmless black mold.
Mold Investigation Tips for Home Inspectors how to find mold, where to look, what is likely to be important. Advice to building inspectors intending to inspect or test for toxic or problematic mold indoors, mold inspection methods, and mold test methods which are valid or invalid
Mold Test Kits - How to Collect and Send Your Own Mold Sample to our mold testing lab
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