Publicação
Effect of pH on Candida tropicalis virulence factors
| Resumo: | Candidiasis is the most prevalent opportunistic fungal infection of humans and has been increased dramatically in recent years, namely due to Candida tropicalis. The increased incidence of C. tropicalis in human candidiasis may be in part due to the improvement of the identification methods, the increase incidence of immunocompromised patients and to the fact that C. tropicalis is well adapted to environmental stress conditions and highly tolerant to antifungal drugs. Candida tropicalis’ pathogenicity is mediated by a number of virulence factors, as adhesion and biofilm formation on abiotic and biotic surfaces, secretion of hydrolytic enzymes and filamentous forms development. Additionally, C. tropicalis strains are causative agents of local and systemic infections in a diversity of human body niches with a high range of pH values and their exact adaptation mechanism to this environmental factor is not yet fully understood. Thus, the main goal of the work reported in this thesis was to investigate the role of pH on C. tropicalis virulence, namely on biofilm formation ability (structure and matrix composition), filamentous forms development and on its capability to colonize/invade human vaginal epithelia. The proteome of biofilm cells grown at different pHs was also examined, in order to disclose alterations in protein profiles as a result of C. tropicalis ability to adapt to different human body niches. With this work it was possible to demonstrate that C. tropicalis clinical isolates were able to forms biofilm at acidic, neutral and alkaline environmental although these were more extent at alkaline environments (pH 8.0). Moreover, SEM and CLSM images revealed that environmental pH (pH 7.0 and 8.0) is an important inducer of filamentation, colonization and invasiveness of human vaginal tissue. The proteins profile expressed by C. tropicalis biofilms cells growing at pH 4.0, 7.0 and 8.0 and obtained by electrophoresis 2-D were compared, and the results revealed consistent differences among pHs, with highest similarity between the acidic and neutral environments comparatively to alkaline environment. Summarizing, this work underlines C. tropicalis adaptability to pH and the influence of environmental pH on its virulence factors. |
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| Autores principais: | Ferreira, Carina Sofia Vieira |
| Assunto: | Engenharia e Tecnologia::Biotecnologia Industrial |
| Ano: | 2015 |
| 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: | Candidiasis is the most prevalent opportunistic fungal infection of humans and has been increased dramatically in recent years, namely due to Candida tropicalis. The increased incidence of C. tropicalis in human candidiasis may be in part due to the improvement of the identification methods, the increase incidence of immunocompromised patients and to the fact that C. tropicalis is well adapted to environmental stress conditions and highly tolerant to antifungal drugs. Candida tropicalis’ pathogenicity is mediated by a number of virulence factors, as adhesion and biofilm formation on abiotic and biotic surfaces, secretion of hydrolytic enzymes and filamentous forms development. Additionally, C. tropicalis strains are causative agents of local and systemic infections in a diversity of human body niches with a high range of pH values and their exact adaptation mechanism to this environmental factor is not yet fully understood. Thus, the main goal of the work reported in this thesis was to investigate the role of pH on C. tropicalis virulence, namely on biofilm formation ability (structure and matrix composition), filamentous forms development and on its capability to colonize/invade human vaginal epithelia. The proteome of biofilm cells grown at different pHs was also examined, in order to disclose alterations in protein profiles as a result of C. tropicalis ability to adapt to different human body niches. With this work it was possible to demonstrate that C. tropicalis clinical isolates were able to forms biofilm at acidic, neutral and alkaline environmental although these were more extent at alkaline environments (pH 8.0). Moreover, SEM and CLSM images revealed that environmental pH (pH 7.0 and 8.0) is an important inducer of filamentation, colonization and invasiveness of human vaginal tissue. The proteins profile expressed by C. tropicalis biofilms cells growing at pH 4.0, 7.0 and 8.0 and obtained by electrophoresis 2-D were compared, and the results revealed consistent differences among pHs, with highest similarity between the acidic and neutral environments comparatively to alkaline environment. Summarizing, this work underlines C. tropicalis adaptability to pH and the influence of environmental pH on its virulence factors. |
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