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Physiological characteristics of environmental isolates of pathogenic dematiaceous fungi
Abstract:
A total of 39 environmental isolates of pathogenic dematiaceous fungi (Fonsecaea pedrosoi: 14 isolates, Phialophora verrucosa: 6, Cladosporium carrionii: 9, Exophiala jeanselmei: 2, Ramichloridium subulatum: 6, Cladosporium tenuissimum: 1 and Phaeoisaria clematidis: 1) were evaluated for their various physiological characteristics including the ability to produce extracellular enzymes. Significant physiological characteristics included the ability of isolates of all the species except C. tenuissimum to decompose tyrosine, lyse human red blood cells, conversion of R. subulatum from filamentous to yeast form when cultured on Czapek-Dox agar and also on blood agar and the growth of C. tenuissimum on Sabouraud dextrose agar incorporating 3.6 M NaCl. Isolates of all the species except those of C. carrionii produced lipase, while only the isolates of P. verrucosa, E. jeanselmei and Ph. clematidis were positive for phospholipase.
Insights
This study evaluated physiological traits of pathogenic dematiaceous fungi. Key findings include species-specific enzyme production and growth characteristics, aiding in fungal identification and understanding pathogenicity.
Area of Science:
- Medical Mycology
- Environmental Microbiology
- Fungal Physiology
Background:
- Dematiaceous fungi are a group of pathogenic molds.
- Environmental isolation of these fungi is crucial for understanding their ecology.
- Physiological characteristics aid in the identification and classification of fungal species.
Purpose of the Study:
- To evaluate the physiological characteristics of 39 environmental isolates of pathogenic dematiaceous fungi.
- To identify key enzymatic and growth properties of various fungal species.
- To differentiate between species based on their physiological profiles.
Main Methods:
- Culturing of 39 environmental isolates belonging to seven species of pathogenic dematiaceous fungi.
- Assessment of physiological characteristics including extracellular enzyme production (tyrosine decomposition, red blood cell lysis, lipase, phospholipase).
- Evaluation of growth conditions and morphological changes (filamentous to yeast form conversion, salt tolerance).
Main Results:
- Isolates of most species, except Cladosporium tenuissimum, decomposed tyrosine and lysed human red blood cells.
- Lipase production was observed in all species except Cladosporium carrionii.
- Phospholipase activity was detected only in Phialophora verrucosa, Exophiala jeanselmei, and Phaeoisaria clematidis.
- Ramichloridium subulatum exhibited a filamentous to yeast form conversion under specific culture conditions.
- Cladosporium tenuissimum demonstrated growth on Sabouraud dextrose agar with 3.6 M NaCl.
Conclusions:
- Physiological characteristics like enzyme production and growth patterns are valuable for differentiating pathogenic dematiaceous fungi.
- The study provides insights into the metabolic capabilities and environmental adaptability of these fungi.
- Understanding these traits can contribute to improved diagnostics and management of fungal infections.