A Dermatophyte Growing on DTM

Photograph of an uninoculated flask of dermatophyte test medium (DTM) showing its initial acidic pH (Phenol red is yellow).
Photograph of a dermatophyte growing in a flask of dermatophyte test medium (DTM) showing an alkaline pH (Phenol red is red).
An uninoculated flask of DTM with its acidic pH (yellow)
A dermatophyte growing on DTM. Note alkaline end products.
As the dermatophytes, such as this Microsporum, utilize the keratin in the medium during their growth, they produce alkaline end products. These products cause the phenol red pH indicator in the DTM to turn from its initial yellow color (acid) to red (alkaline).
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Microbiology Laboratory Manual by Gary E. Kaiser, PhD, Professor of Microbiology
is licensed under a Creative Commons Attribution 4.0 International License.
Last updated: September, 2017