Universidade do Minho. Departamento de Engenharia Biológica (DEB)
Abstract
Biofilms are structurally complex microconsortia of surface adhering cells embedded within
an extracellular matrix (ECM) composed of substances produced and secreted by cells or
derived from cell lysis. One of the recently discovered bacterial biofilms ECM components is
the extracellular DNA (eDNA). Although the investigation on eDNA in fungal biofilms is
scarce, preliminary studies suggest that eDNA may play a role in biofilms formed by the
opportunistic fungal pathogen Candida albicans. Thus, the present study aimed at
determining the eDNA content of C. albicans SC5314 biofilm ECM and the effect of DNase I
treatment on biofilm formation and biofilm cells susceptibility to antifungals, as indicators of
the role of eDNA in C. albicans biofilms.
Results from our experiments showed that the ECM of C. albicans biofilms formed under
conditions of flow for 48 h contained 3045.4 ± 227.3 ng eDNA/mg of protein. Additionally,
using a microtiter plate model, we observed that different DNase treatments (0.02 - 2 mg/ml)
did not affect further biofilm development by C. albicans adherent cells. However, DNase (>
0.03 mg/ml) promoted a general biomass reduction on C. albicans preformed biofilms.
Finally, DNase (0.13 mg/ml) did not change C. albicans biofilm cells susceptibility to
fluconazole, but increased their susceptibility to amphotericin B and caspofungin, as
indicated by the lower SMIC compared to biofilms grown without DNase.
This work presents evidence for the role of eDNA in C. albicans biofilm integrity and
antifungal resistance consistent with eDNA being a key element of the ECM
