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Abstract:
The survival of propagules from 4 pathogenic fungi, Trichophyton mentagrophytes, Trichosporon cutaneum, Candida albicans, and Microsporum gypseum was studied in seawater subjected to different temperature (20--35 degrees C) and salinity (6--50%) levels in diurnal rhythm of 12 h cycles. Survival was measured by viability of propagules over a period of 52 weeks. All fungi, except T. cutaneum at 35 degrees C survived the experimental conditions for 52 weeks. Temperature was the most influential factor. When temperature increased, M. gypseum responded with enhanced viability whereas survival for C. albicans and T. cutaneum was inhibited. At 35 degrees C, T. cutaneum was not viable after 6--7 weeks even though it survived the initial 5 weeks with less loss of viability than the other test organisms. No correlation was seen between salinity level and loss of viability. Diurnal light had an inhibitory effect on T. cutaneum and C. albicans survival under in vitro conditions approximating those of seawater in Hawaii. M. gypseum had the highest level of survival over 52 weeks under usual in situ conditions simulated in vitro, followed by T. mentagrophytes, T. cutaneum, and C. albicans. Survival for 52 weeks even when salinity and temperature levels exceed those of the natural habitat indicates that seawater which washes sand beaches can be an environmental niche for potentially pathogenic fungi.
Insights
Pathogenic fungi like Microsporum gypseum can survive in seawater for up to 52 weeks, indicating beaches may serve as a niche. Temperature significantly impacts fungal survival, while salinity shows no correlation.
Area of Science:
- Environmental microbiology
- Medical mycology
Background:
- Pathogenic fungi can pose health risks in recreational water environments.
- Understanding fungal survival in marine settings is crucial for public health.
Purpose of the Study:
- To investigate the survival of four pathogenic fungi in simulated seawater conditions.
- To determine the influence of temperature, salinity, and light on fungal viability over 52 weeks.
Main Methods:
- Four pathogenic fungi (Trichophyton mentagrophytes, Trichosporon cutaneum, Candida albicans, Microsporum gypseum) were exposed to varying temperatures (20-35°C) and salinities (6-50%) in a 12-hour diurnal cycle.
- Fungal propagule viability was assessed weekly for 52 weeks.
- In vitro conditions simulated seawater in Hawaii.
Main Results:
- Microsporum gypseum demonstrated the highest survival rate over 52 weeks.
- Temperature was the most critical factor; higher temperatures inhibited Candida albicans and Trichosporon cutaneum.
- Trichosporon cutaneum viability decreased significantly at 35°C after 6-7 weeks.
- Salinity did not correlate with fungal viability loss.
- Diurnal light inhibited Trichosporon cutaneum and Candida albicans survival.
Conclusions:
- Seawater, particularly at sand beaches, can act as a viable environmental niche for pathogenic fungi.
- Fungal survival is influenced by temperature and light, suggesting potential seasonal variations in risk.
- Further research is needed to assess the public health implications of pathogenic fungi in marine environments.