The role of proteins of the outer membrane of Shewanella oneidensis MR-1 in the formation and stabilization of silver sulfide nanoparticles

Abstract

Silver sulfide nanoparticles stable in aqueous solutions were obtained in presence of the cells of the bacterium Shewanella oneidensis MR-1 in aqueous solution containing an equimolar mixture of AgNO₃ and Na₂S₂O₃. Proteins absorbed on the surface of Ag₂S nanoparticles were identified for the first time by MALDITOF/TOF. Among these proteins, multiheme cytochromes MtrC and OmcA, as well as the MtrB membrane porin, which forms a complex on the outer cell membrane, were detected. It was shown that an insoluble precipitate consisting of agglomerated Ag₂S nanoparticles with a wide size distribution was formed in the absence of the cells. The role of the detected proteins in the mechanism of the formation and stabilization of the Ag₂S nanoparticles in the studied system is discussed.