INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
CARACTERIZACIÓN BIO-ELECTROQUÍMICA DE CULTIVOS LÍQUIDOS AEROBIOS DE LA MICROALGA Scenedesmus dimorphus
Autor/es:
BELIGNI, M. VERÓNICA; BUSALMEN, JUAN PABLO
Reunión:
Congreso; X CONGRESO ARGENTINO DE MICROBIOLOGIA GENERAL SAMIGE; 2014
Institución organizadora:
Samige
Resumen:
The use of microbial metabolism for the conversion of chemical energy into electricity has given raise to a series of bio-electrochemical devices. In the most promising approach, bacteria that transfer electrons directly to electrodes, have been utilized in hybrid anodes of microbial fuel cells (MFCs). Current production in MFCs depends largely on the kinetics of the reduction that takes place at the cathode. Power output has been shown to be proportional to the concentration of dissolved O2 in the catholyte, but increasing the dissolved O2 concentration is limited by its solubility in water. The addition of photosynthetic organisms to the cathodic compartment of MFCs has been proposed as a way to reduce cathodic limitation, due to their ability to increase the concentration of O2 to much higher concentrations than its solubility, process driven by the photo-oxidation of water during photosynthesis. In addition, this strategy has the environmental added value of enabling electricity generation from sunlight and carbon dioxide. The bio-electrochemical properties of photosynthetic microorganisms have not been characterized to detail. Specifically, although electron transfer between cathodes and microalgae has been proposed, the mechanisms have not been described. In this work, we initiate the characterization of bio-electrochemical properties of the green microalga Scenedesmus dimorphus in aerobic liquid cultures, in relation to three different electrode materials: stainless steel, graphite and platinum. We measured the open circuit potential (OCP) of cell cultures at different cell densities, either during light or dark periods. We also measured current generation when potentials from 0 to -0.9 V were applied. OCPs showed characteristic values for each material, with slight variations with culture conditions. Current generation on the other side, depended on the light:dark cycle, but this was strictly related to the concentration of O2 in the culture. In fact, current production using the three electrode materials showed a linear relationship with O2 over a wide range of concentrations, from 2 to above 20 mg/L of dissolved O2 . Platinum proved to be the best of the three electrode materials. Current production using platinum was 3-fold higher than using graphite and 2- to 6-fold higher than that provided by stainless steel at the most negative potentials that were applied (-0.4 to -0.9 V). Furthermore, at potentials more compatible with the use as a bio-cathode in Geobacter sp. MFCs (e.g. -0.15 V), platinum was 8-fold better than graphite and 60-fold better than stainless steel for current generation. However, considering the high cost of platinum, graphite electrodes constitute, overall, an appropriate option for use in photosynthetic MFCs