Blastomyces dermatitidis, PCR based detection of its DNA from natural soil samples.

Tom Volk's Fungus of the Month for April 2007

by Joshua Burgess, William Schwan, and Tom Volk.

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Blastomyces dermatitidis is dimorphic, changing from mycelium to yeast and back depending on the temperature Oh no! Another repeat! This month's fungus, Blastomyces dermatitidis is featured once again to highlight some of our work. We wrote about this fungus earlier on this page, so I recommend reading that page first as a good intro to Blastomyces before going on with this paper.

Burgess, Joshua, William Schwan, and Thomas J. Volk. 2006. PCR based detection of DNA from the human pathogen Blastomyces dermatitidis from natural soil samples. Medical Mycology 44:741-748.


Blastomyces dermatitidis is the dimorphic fungal agent of blastomycosis, a disease that primarily affects humans and dogs. The clinical appearance of this mycosis is well characterized, but there is still little known about its environmental niche, having been isolated from nature only 21 times. We have developed a PCR-based assay to detect B. dermatitidis from soil samples using primers specific to a portion of the promoter region of the BAD1 virulence gene. An internal standard control, pTJV2-2, was constructed to validate the results from soil samples. The PCR detection limits for the control plasmid and B. dermatitidis genomic DNA were 0.1 and 500 femtograms, respectively. No PCR cross-reactivity was observed against bacteria, actinomycetes, and 13 other fungi that are genetically related or found in the same geographic areas. In spiked soil samples, this method was sensitive to 304 copies of pTJV2-2 DNA and 8,450 live B. dermatitidis yeast cells. Three of eight natural soil samples from a dog kennel near Lexington, KY in which dogs suffered from blastomycosis were positive using the described method, demonstrating its utility in detecting B. dermatitidis in its natural surroundings.

You can read a PDF of the article by clicking here

I hope you enjoyed learning about Blastomyces dermatitidis and its environmental niche. We hope that the methods described in this paper will lead to further studies in determining the natural niche of Blastomyces in nature

If you have anything to add, or if you have corrections, comments, or recommendations for future FotM's (or maybe you'd like to be co-author of a FotM?), please write to me at my email address

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