Physicochemical properties of electroactive yeasts surfaces: Seen any effect on extracellular electron transfer and biofilm formation?

This study aimed to understand the biofilm formation of three electroactive yeasts on carbon felt electrode based on XDLVO theory and how physicochemical properties of both electrode and microorganisms surfaces affect current generation. The three yeast (W. anomalus, C. tropicalis and P. fermentans) strains showed a maximum current density of 34±0.002, 30±0.004 and 28±0.004 mA/m². The physicochemical characterization of the electrode and the yeast stains surfaces was carried out by the sessile drop technique. Moreover, the interfacial free energy of surface adhesion to the carbon was determined. Based on the value of interfacial free energy, the three yeasts should be able to attach to carbon felt. It was established by ESEM and epifluoresence microscopy that the three yeast strains adhered on carbon felt, as predicted theoretically, with adhesion levels of 4,34 %, 3,15 % and 2,85 % found with W. anomalus, C. tropicalis and P. fermentans, respectively. The correlations between physicochemical properties of the three yeast strains and the current generated were evaluated. Pearson s correlation showed that the current generated correlated significantly and negatively with cell surface hydrophobicity (r = - 0.89, P= 0.05) and significantly and positively with electron acceptor character γ+ (r = 0.84, P=0.01). However, there was no significant correlation with electron donor character γ-.