Physicochemical Characterization of Acidiphilium sp. Biofilms

The biofilm formation of a strain of the extremophile bacterium Acidiphilium sp., capable of donating electrons directly to electrodes, was studied by different surface characterization techniques. We develop a method that allows the simultaneous study of bacterial biofilms by means of fluorescence microscopy and atomic force microscopy (AFM), in which transparent graphitic flakes deposited on a glass substrate are used as a support for the biofilm. The majority of the cells present on the surface were viable, and the growth of the biofilms over time showed a critical increase of the extracellular polymeric substances (EPS) as well as the formation of nanosized particles inside the biofilm. Also, the presence of Fe in Acidiphilium biofilms was determined by X‐ray photoelectron spectroscopy (XPS), whereas surface‐enhanced infrared absorption spectroscopy indicated the presence of redox‐active proteins. Acidiphilium biofilms are grown on graphitic flakes and are characterized by different physicochemical techniques. Combined fluorescence–AFM microscopy is applied to study the biofilm formation over time and to detect nanosized particles that are, in turn, analyzed by X‐ray photoelectron spectroscopy and attenuated total reflection surface‐enhanced infrared absorption spectroscopy.