After the defined times of incubation, the medium was aspirated and non-adherent cells removed by washing the wells with sterile ultra-pure water. Following, the adherent cells were fixed with 1 ml of methanol, which was removed after 15 min of contact. The plates were allowed to dry at room temperature, and 1 ml of CV (1% v/v) was added to each well and incubated for 5 min. The wells were then gently washed with sterile, ultra-pure water, and 1 ml of acetic acid (33% v/v) was added to release and dissolve the stain. The absorbance of the obtained solution was read at 570 nm in triplicate in a microtiter plate reader (Bio-Tek Synergy HT, Izasa, Lisbon, Portugal). The final absorbance was

standardized according to the volume find more of acetic acid and area of the wells (abs/cm2). Three to five independent assays were performed for each experiment. Scanning electron microscopy Structure of adhered and/or biofilm cells were examined by Scanning Electron Microscopy (SEM). For this, medium and non-adherent cells were extracted as described for CV staining

(above). Samples were then dehydrated with alcohol (using click here 70% ethanol for 10 min; 95% ethanol for 10 min and 100% of ethanol for 20 min) and air dried for 20 min. The bases of the wells were cut and were kept in a desiccator until analysed. Samples were then covered with gold for visualization in a S-360 scanning electron microscope (Leo, Cambridge, USA). Acknowledgements Authors would like to acknowledge Joana Azeredo and Rosário Oliveira for BI 2536 manufacturer enabling the experiments on biofilms formation in the Thalidomide Laboratory of Applied Microbiology from CEB/IBB, and to Isabel Miranda and Ana Dias from Laboratory of Microbiology Faculty of Medicine, University of Porto, for their assistance on hydrophobicity experiments. We also thank Hugh S. Johnson for the several critical readings of the manuscript regarding proper English usage. Sónia Silva is supported by a PhD grant from FCT, Refa SFRH/BD/28341/2006. Electronic supplementary material Additional file 1: Growth inhibition halos in the presence

of polyenes. Sterile filter disks were impregnated with 25 μg/ml amphotericin B (AmpB) and 2.5 μg/ml nystatin (Nys) and placed on top of YPD methyl-blue plates seeded with 5 ml of a wt or Cagup1Δ null mutant strain mid-exponential phase cultures. Halos of growth inhibition were measured (mm) after 2 or 3 days. (PNG 52 KB) Additional file 2: Growth inhibition halos in the presence of EBIs. Sterile filter disks were impregnated with the drugs and placed on top of YPD methyl-blue plates seeded with 5 ml of a wt or Cagup1Δ null mutant strain mid-exponential phase cultures. (1) YPD plates (control) and plates with the impregnated disks (2) clotrimazole 137.6 μg/ml, (3) ketoconazole 212.6 μg/ml, (4) fluconazole 91.8 μg/ml and (5) fenpropimorph 80 μg/ml. Halos of growth inhibition were measured (mm) after 2 or 3 days. (PNG 123 KB) Additional file 3: Colony morphology under non-hypha-inducing conditions.