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Chlamydospore formation by Paracoccidioides brasiliensis mycelial form
Abstract:
To investigate the role of some adverse environmental conditions in chlamydospore formation by the mycelial form of P. brasiliensis, we cultured four P. brasiliensis isolates (18, Bt4, 1183, Pb9) at 25 degrees C within solid agar medium either rich or poor in nutrients. Isolates 18 and 1183 were also cultured under anaerobiosis in a nitrogen atmosphere. Isolate 18 produced great number of terminal and intercalary chlamydospore after 7-10 days of culture in a medium poor in nutrients (2% agar with 0.1% dextrose and polypepton). The three other isolates also produced chlamydospores under the same conditions, but in lower numbers. Chlamydospore production by isolate 18 was abolished when the fungus was cultured in two agar media rich in nutrients (brain heart infusion and potato dextrose agar). Anaerobic incubation of isolate 18 under an atmosphere of N2 showed small mycelial outgrowth with numerous chlamydospores. At the electron microscopical level, the chlamydospores showed one or various nuclei and numerous mitochondria, indicating great potential for further development. Accordingly, chlamydospores produced multiple budding after only 24 h incubation at 35 degrees C. The results demonstrate that under adverse environmental conditions P. brasiliensis mycelial form produces chlamydospores within a short period of time.
Insights
Adverse environmental conditions trigger chlamydospore formation in Paracoccidioides brasiliensis (P. brasiliensis) mycelial forms. These structures are viable and can bud, indicating their role in fungal development and survival.
Area of Science:
- Mycology
- Environmental Microbiology
- Fungal Pathogenesis
Background:
- Paracoccidioides brasiliensis (P. brasiliensis) is a fungus that causes paracoccidioidomycosis.
- The mycelial form of P. brasiliensis can differentiate into chlamydospores under specific conditions.
- Understanding chlamydospore formation is crucial for comprehending the P. brasiliensis life cycle and disease transmission.
Purpose of the Study:
- To investigate the influence of adverse environmental conditions on chlamydospore formation in P. brasiliensis.
- To characterize the morphology and developmental potential of P. brasiliensis chlamydospores.
Main Methods:
- Culturing four P. brasiliensis isolates on nutrient-rich and nutrient-poor agar media at 25°C.
- Incubating P. brasiliensis under anaerobic conditions with a nitrogen atmosphere.
- Utilizing electron microscopy to examine chlamydospore ultrastructure.
- Assessing chlamydospore budding potential at 35°C.
Main Results:
- Nutrient-poor media significantly induced chlamydospore formation in P. brasiliensis isolates.
- Isolate 18 exhibited abundant chlamydospore production, while other isolates produced fewer.
- Chlamydospore formation was suppressed in nutrient-rich media.
- Anaerobic conditions also promoted chlamydospore production.
- Electron microscopy revealed chlamydospores with nuclei and mitochondria, suggesting developmental capacity.
- Chlamydospores readily budded at 35°C, indicating rapid development.
Conclusions:
- Adverse environmental conditions, particularly nutrient limitation and anaerobiosis, are potent stimuli for P. brasiliensis chlamydospore formation.
- P. brasiliensis chlamydospores are viable, possess developmental potential, and can rapidly bud, contributing to the fungus's survival and propagation.
- Chlamydospore formation represents an adaptive response of the P. brasiliensis mycelial form to unfavorable environments.