OPPORTUNITIES BEHIND GEOBACTER AU RESPIRATION. HYBRID NANOSTRUCTURES ISOLATION AND CHARACTERIZATION

MARIA VICTORIA ORDÓÑEZ; INCHAURRONDO JI; HOPPE, C; BUSALMEN JP

Parana

Congreso; LIV Reunion Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2018

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Geobacter sulfurreducens is an anaerobic gram(?) bacteria capable of using a wide range of electron acceptor including insoluble Fe(III) (hydr)oxides and anode electrodes, thus expelling electrons beyond cells limits. C-type cytochromes named Omc (Outter membrane cytochromes) are the main redox proteins involved in external electron transfer. We have previously described the capacity of Geobacter to use Au(III) ions as electron acceptor, thus forming AuNPs that help improve current production in electrogenic biofilms. In this work we go forward on the isolation and characterization of nanostructures synthetized by Geobacter cultures grown in batch. Au respiration was performed at standard growing conditions for 1 week period. Soluble fraction containing gold NPs as well as biological material was then obtained and applied to a sucrose discontinuous gradient to achieve nanoparticle size separation. TEM microscopy from different fractions showed that NPs separation from cellular debris was achieved finding smaller NPs (2-10 nm) in 30% sucrose fraction and larger NPs in 60% sucrose fraction mostly of spherical shape. Perfoming SDS polyacrylamide electrophoresis of these fractions we detected several proteins together with NPs, including c-type cytochromes as observed by TMBZ stain. Of 5 cytochrome detected in the initial material, four of MR 78, 65, 50 and 45 kDa were also found in the sucrose fractions. Results indicate conjugates of cytochromes-AuNPs would form, thus obtaining hybrid nanostructures with particular electrochemical properties that were analysed with electrochemical techniques. This results may also explain Au(III) respiration mechanism.