Metabolic profile of Candida albicans and Candida parapsilosis interactions within dual-species biofilms.

Within the oral cavity, the ability of Candida species to adhere and form biofilms is well-recognized, especially when Candida albicans is considered. Lately, a knowledge gap has been identified regarding dual-species communication of Candida isolates, as a way to increase virulence, with evidences being collected to support the existence of interactions between C. albicans and Candida parapsilosis. The present work evaluated the synergistic effect of the two Candida species, and explored chemical interactions between cells, evaluating secreted extracellular alcohols and their relation with yeasts' growth and matrix composition. A total of four clinical strains of C. albicans and C. parapsilosis species, isolated from single infections of different patients or from co-infections of a same patient, were tested. It was found that dual-species biofilms negatively impacted the growth of C. parapsilosis and their biofilm matrix, in comparison with mono-species biofilms, and had minor effects on the biofilm biomass. Alcohol secretion revealed to be species- and strain-dependent. However, some dual-species cultures produced much higher amounts of some alcohols (E-nerolidol and E, E-Farnesol) than the respective single cultures, which proves the existence of a synergy between species. These results show evidence that interactions between Candida species affect the biofilm matrix, which is a key element of oral biofilms.