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Evaluation of proteolytic activity to differentiate some dematiaceous fungi
A Espinel-Ingroff1, P R Goldson, M R McGinnis
1Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0504.
Abstract:
A total of 123 isolates of Cladosporium spp., Exophiala spp., Fonsecaea spp., Lecythophora hoffmannii, Phaeoannellomyces werneckii, Phialophora spp., Wangiella dermatitidis, and Xylohypha bantiana were tested for proteolytic activity by using 26 different formulations of gelatin, milk, casein, and Loeffler media. Other physiological properties examined included hydrolysis of tyrosine and xanthine, sodium nitrate utilization in Czapek Dox agar, and thermotolerance. Isolates of Exophiala jeanselmei, Fonsecaea compacta, Fonsecaea pedrosoi, W. dermatitidis, and X. bantiana lacked proteolytic activity. Proteolytic activity was variable among the remaining species, depending on the type of medium used. Thermotolerance had value in distinguishing some taxa.
Insights
This study investigated proteolytic activity in various fungal species. Proteolytic activity varied by species and medium, with thermotolerance aiding in distinguishing some fungal taxa.
Area of Science:
- Medical Mycology
- Fungal Physiology
Background:
- Fungi, particularly dematiaceous molds, can cause opportunistic infections.
- Understanding their physiological characteristics, such as proteolytic activity, is crucial for accurate identification and clinical management.
Purpose of the Study:
- To evaluate the proteolytic activity and other physiological properties of 123 isolates from various dematiaceous fungal species.
- To determine the utility of these properties, including thermotolerance, in fungal identification.
Main Methods:
- Tested 123 isolates of Cladosporium, Exophiala, Fonsecaea, Lecythophora hoffmannii, Phaeoannellomyces werneckii, Phialophora, Wangiella dermatitidis, and Xylohypha bantiana.
- Assessed proteolytic activity using 26 formulations of gelatin, milk, casein, and Loeffler media.
- Examined hydrolysis of tyrosine and xanthine, sodium nitrate utilization, and thermotolerance.
Main Results:
- Exophiala jeanselmei, Fonsecaea compacta, Fonsecaea pedrosoi, W. dermatitidis, and X. bantiana isolates showed no proteolytic activity.
- Proteolytic activity was variable among other species and dependent on the specific medium used.
- Thermotolerance proved useful for distinguishing certain fungal taxa.
Conclusions:
- Proteolytic activity is not a universal characteristic among the tested dematiaceous fungi.
- A combination of physiological tests, including assessment of proteolytic activity and thermotolerance, can aid in the differentiation of these fungal species.