Geobacter sulfurreducens electroactive biofilms on Fe2O3/FTO support-electrodes for developing a sodium acetate electrochemical biosensor

Abstract

Geobacter sulfurreducens is an essential microorganism in biogeochemical cycles. It is used biotechnologically in bioremediation and electricity production. The importance of G. sulfurreducens lies in its capacity to contact extracellular electron acceptors, including several electrode materials. Taking advantage of the versatility of G. sulfurreducens to grow on different surfaces, it is possible to design and synthesize new electrodes that can expand and improve the applications of these bacteria. In this work, we performed multidisciplinary research studies to demonstrate an innovative application of this well-known microbial system. The interaction between fluorine-doped tin oxide (FTO) and ordinary glass with G. sulfurreducens was enhanced by modifying the surface with Fe2O3 films. As confocal laser microscopy analyses revealed, the enhancement promoted biofilm development, whose parameters were significantly better than the bare support-electrodes. Furthermore, we provided evidence that G. sulfurreducens interacted with and dissolved the Fe2O3 film during incubation. Then, when we added sodium acetate to the system, the microbial metabolism was activated and decreased the electrochemical response of this compound. We benefited from that behavior to develop a voltammetric-based robust biosensor that could measure sodium acetate at high concentrations with an acceptable linear interval, from 10 to 110 mM, with LOD = 5.9 ± mM and LOQ = 18.1 ± 1.5 mM.