Microorganism is the driver for the biogeochemical cycing of metals in the environment.Noble metal ions,such as gold and silver,are highly toxic to most microbial cells.To resist their toxicity,microorganisms have developed various mechanisms for self-protection.The insights gained from the bacteria response to Au(Ⅲ)/Ag(Ⅰ)should improve our understanding of the fundamental mechanisms of gold and silver resistance in microorganisms and the impact of microbial processes on metal cycling in the environment.Herein,we report biogenic synthesis of gold and silver nanoparticles in Pantoea sp.IMH(JX861130).To the best of our knowledge,it is the first report that a strain belonging to Pantoea could reduce Au(Ⅲ)and Ag(Ⅰ).HRTEM images of whole cell and thin sections of strain IMH incubated with Au(Ⅲ)and Ag(Ⅰ)showed that abundant nanoparticles were distributed with increasing particle size from about 4 nm throughout the cytoplasm,~10 nm on the cell surface to 50 nm in the culture medium.XANES results indicated the nanoparticles formed in the microbial environment were Au(0)and Ag(0).SAED and XRD analysis of the gold and silver nanoparticles showed that the crystal planes of Au NPs were(111),(200),and(220),while that of Ag NPs was(111),validating the formation of metallic gold and silver crystals.FTIR and SERS analysis suggested the presence of capping protein/peptides,which may contribute to the stability of the biogenic gold and silver nanoparticles.Our whole genome sequencing results showed that Pantoea sp.IMH has MerR family transcriptional regulators(cueR/soxR)and gene clusters of As reduction(arsHCR),Cu resistance(copA).Therefore,the arsenate reductase ArsC,Cu(Ⅱ)exporting ATPase CopA,and MerR family transcriptional activator CueR/SoxR may be involved in Au(Ⅲ)bioreduction and resistance.