Extraction of extracellular polymeric substances from the acidophilic bacterium Acidiphilium 3.2Sup(5)

Extraction of extracellular polymeric substances (EPS) from Acidiphilium 3.2Sup(5) was investigated using five methods: EDTA, NaOH, ion exchange resin, heating and centrifugation. The bacterium studied presents promising application in microbial fuel cells (MFCs). The degree of cellular lysis provoked by each method was determined by UV-visible spectroscopy of cultures before and after EPS extraction. In addition, two electron microscopy techniques (TEM and SEM) were employed to determine the degree of attachment and the growth of the biofilm overtime on two solid supports: carbon fibre cloth and graphite rods. The main constituents of the EPS extracted by all methods were proteins and carbohydrates, as confirmed by FT-IR analysis, showing the major presence of carboxylic, hydroxylic and amino groups. The greater extractions of EPS were obtained using EDTA. This method also produced a less degree of cellular lysis. Furthermore, both the amount and the chemical composition of EPS strongly depended on the extraction method used.