The biogeochemical cycles of chalcogens play a major role in the environment, where the cycles of selenium (Se) and tellurium (Te) have been much less studied compared to those of the omnipresent elements oxygen and sulfur. Removal and recovery of Se/Te from wastes is desirable for ecosystem well-being and meeting future needs of these resources. To survive and grow, bacteria harvest energy by shuttling electrons to a variety of electron acceptors. Interestingly, a number of elements, including the Se/Te oxyanions are redox-active and can be used as electron acceptors by microbes. Thus, microbial metabolism alters solubility, thereby influencing transport, bioavailability and toxicity of the chalcogen oxyanions. In natural and engineered settings, biofilms are implicated in the transformation and immobilization of Se/Te. But, to develop industrial scale processes for removal and recovery, the rate must be accelerated. Identification of biofilm-components that mediate electron transfer to soluble Se/Te and solid-phase Se/Te might help to develop high-rate industrial scale processes. This IIF focuses on the identification of biofilm-components, exogenous electron shuttles that accelerate the reduction and recovery of Se/Te. A multi-disciplinary approach will be used for characterizing the reduction mechanisms, physiology and biofilm structure, thus the applicant acquires new skills available at the host institute. Experiments will be designed to find novel endogenous molecules, exogenous electron shuttles accelerating bacterial reduction of soluble Se/Te and solid-phase Se/Te. The fundamental insights obtained from the lab-scale studies will be translated to reactor-scale experiments for developing practical applications aiming at the removal and recovery as elemental Se/Te. The overall goal of this IIF is to train the applicant to develop more robust, economical and sustainable biotechnological processes for removal and recovery of Se/Te from industrial effluents.