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

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. © 2016, Pleiades Publishing, Inc.