| Congresso Brasileiro de Microbiologia 2023 | Resumo: 20-2 | ||||
Resumo:A wide variety of fungal species inhabit the soil and perform functions such as recycling compounds, mobilizing nutrients for plants, and infecting susceptible hosts like insects. However, for these activities to take place, the fungi must be able to cope with antifungal activities, including those performed by free-living amoebas. Amoebas can predate on microorganisms through phagocytosis and digestion, using them as a source of nutrition. The survival of fungal cells within amoebae depends on their ability to produce virulence determinants. These include secondary metabolites, which are bioactive molecules derived from the activity of proteins encoded by genes that are clustered together in fungal genomes, known as biosynthetic gene clusters (BGCs). To increase our knowledge about fungal secondary metabolites with potential activity against amoebas, we used entomopathogenic fungi to evaluate their outcome when confronted with amoeba cells. The rationale is that fungal pathogens, such as the entomopathogenic Metarhizium anisopliae and Beauveria bassiana, would be better suited to survive the antifungal activity posed by amoebas than other soil-borne fungal species. This improved fitness would have arisen from the evolution of virulence determinants, such as several BGCs. To evaluate this hypothesis, we conducted interaction assays between the amoeba Acanthamoeba castellanii and some soil-borne fungi, including the entomopathogens M. anisopliae and B. bassiana. As a control, we used Aspergillus niger, which is generally not recognized as a pathogen. We evaluated the phagocytosis rate, conidial germination rate, fungal survival, as well as the mortality rate of A. castellanii. The results revealed that all fungal species were quickly phagocytized by A. castellanii and were capable of germinating inside the host cells. However, both B. bassiana and M. anisopliae displayed an increased proportion of germinated spores compared to A. niger. When comparing the time-course mortality rate of amoeba cells incubated with the distinct fungi, a complex pattern could be observed, suggesting that these fungi use distinct mechanisms to kill amoebas. Further studies employing RT-qPCR to identify expressed BGCs and the generation of null mutants will provide definitive proof of the participation of BGCs as modulators of amoebic antifungal activity. Palavras-chave: Acanthamoeba castellanii, Beauveria bassiana, Biosynthetic gene clusters , Metarhizium anisopliae, Virulence determinants Agência de fomento:CNPq; CAPES; FAPERGS | |||||