Publicação
Identification of environmental fungi with pathogenic potential
| Resumo: | Invasive fungal infections pose a growing threat to immunocompromised patients. Traditionally, environmental fungi are seen as non-pathogenic to humans. However, global warming may select for species that have acquired thermotolerance, a key step toward human pathogenesis. Important virulence factors and antifungal drug resistance have developed in environmental fungi, essential for their survival. The hypothesis that agricultural fungicides drive and select resistance mechanisms in nature before fungi contact the host is gaining attention. The widespread use of azoles in agriculture and medicine, coupled with climate change, may result in the emergence of new pathogenic fungi adapted to higher temperatures and resistant to antifungals. Monitoring environmental fungi with these characteristics may help identify emerging human pathogens and novel fungal diseases. Through isolation by a serial dilution method in media supplemented with fluconazole, this study found that several microorganisms from grape and soil samples treated with antimicrobials showed resistance to the fungicide fluconazole, with 38 % of grape and 45 % of soil isolates being resistant. The results suggested that the resistance persisted in grape samples from areas untreated with antifungals that year. The molecular identification through Sanger Sequencing allowed the detection of soil-resistant colonies of filamentous fungi, fewer bacteria and yeasts, while all resistant colonies from grape samples were yeasts. The microorganisms identified included species from the genera Penicillium, Umbelopsis, Phyllobacterium, Pseudomonas, Saccharomyces and Saitozyma, none of which has been reported as pathogenic. Analysis of virulence factors, such as thermotolerance, enzymatic activity and filamentation ability were performed to assess the potential of the isolated yeast strains to become opportunistic or harmful and revealed that S. cerevisiae presented resistance to fluconazole and could grow at higher temperatures and produce some extracellular enzymatic activity, while S. podzolica was able to filament and produce extracellular enzyme activity, potentially influencing their pathogenic potential. The results highlighted that climate change and continuous antifungal use in wine-making properties might increase resistance among environmental microorganisms and induce characteristics that may be considered virulence factors, thereby increasing their pathogenic potential. |
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| Autores principais: | Vasconcelos, Daniel Luciano Gonçalves |
| Assunto: | Fungi Invasive fungal infection Azole resistance Climate change Virulence factors Fungos Infeção fúngica invasiva Resistência aos azóis Alterações climáticas Fatores de virulência |
| Ano: | 2024 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Invasive fungal infections pose a growing threat to immunocompromised patients. Traditionally, environmental fungi are seen as non-pathogenic to humans. However, global warming may select for species that have acquired thermotolerance, a key step toward human pathogenesis. Important virulence factors and antifungal drug resistance have developed in environmental fungi, essential for their survival. The hypothesis that agricultural fungicides drive and select resistance mechanisms in nature before fungi contact the host is gaining attention. The widespread use of azoles in agriculture and medicine, coupled with climate change, may result in the emergence of new pathogenic fungi adapted to higher temperatures and resistant to antifungals. Monitoring environmental fungi with these characteristics may help identify emerging human pathogens and novel fungal diseases. Through isolation by a serial dilution method in media supplemented with fluconazole, this study found that several microorganisms from grape and soil samples treated with antimicrobials showed resistance to the fungicide fluconazole, with 38 % of grape and 45 % of soil isolates being resistant. The results suggested that the resistance persisted in grape samples from areas untreated with antifungals that year. The molecular identification through Sanger Sequencing allowed the detection of soil-resistant colonies of filamentous fungi, fewer bacteria and yeasts, while all resistant colonies from grape samples were yeasts. The microorganisms identified included species from the genera Penicillium, Umbelopsis, Phyllobacterium, Pseudomonas, Saccharomyces and Saitozyma, none of which has been reported as pathogenic. Analysis of virulence factors, such as thermotolerance, enzymatic activity and filamentation ability were performed to assess the potential of the isolated yeast strains to become opportunistic or harmful and revealed that S. cerevisiae presented resistance to fluconazole and could grow at higher temperatures and produce some extracellular enzymatic activity, while S. podzolica was able to filament and produce extracellular enzyme activity, potentially influencing their pathogenic potential. The results highlighted that climate change and continuous antifungal use in wine-making properties might increase resistance among environmental microorganisms and induce characteristics that may be considered virulence factors, thereby increasing their pathogenic potential. |
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