Interrelation between Cells and Extracellular Polymeric Substances (EPS) from Acidiphilium 3.2Sup(5) on Carbon Surfaces

The interrelation between cells and extracellular polymeric substances (EPS) from the acidophilic bacterium Acidiphilium 3.2Sup(5) was investigated on two different carbon surfaces (carbon fibre cloth and graphite rods). This bacterium was chosen due to its ability to directly transfer electrons to carbon surfaces in aerobic conditions, which makes its use especially attractive in microbial fuel cells (MFC). The characterization of the bacterial adhesion and interrelation with the EPS was carried out using a combination of scanning (SEM) and transmission (TEM) electron microscopy. The extraction of the EPS was performed using EDTA and their characterization accomplished by chemical analyses and FTIR spectroscopy. The cellular lysis provoked by the extraction of EPS was determined by the protein/carbohydrate ratio. Chemical analyses showed that the main components of the EPS were proteins and carbohydrates, whereas FTIR spectroscopy showed the presence of a great majority of carboxyl, hydroxyl and amino groups. The tendency of cells was to adhere to superficial carbon imperfections, which after certain time were covered by a matrix of EPS.