Microorganisms are intimately involved in a plethora of biogeochemical processes in the environment including metal and mineral transformations as well as the cycling of metals, organometals, metalloids and radionuclides. These biogeochemical processes include adsorption, precipitation, and redox oscillations. An understanding of these biogeochemical processes is critical to predict the fate of metals and radionuclides in soils and aquifers, e.g. by developing reactive transport models and updating existing ones. Consequently an in-depth understanding of these processes will aid in devising appropriate remediation schemes. With this background, the proposed session invites abstracts related to laboratory and field-scale studies involving (i) the redox transformation of metals and radionuclides by microbes, their metabolites and autochthonous organic compounds such as humic substances, (ii) metal adsorption, precipitation and uptake by microbes, (iii) nano-scale characterization and reactivity of biogenic minerals, (iv) isotopic fractionation of metals and radionuclides coupled to microbial metabolism, (v) toxicity of metals and nanoparticles to microbes, (vi) evolution of microbial communities in response to metals, radionuclides and concentration gradients, and (vii) non-invasive in-situ and ex-situ analytical techniques including microscopy and spectroscopy to probe microbe-metal interactions.