Heavy metals, electrophilic toxins and reactive oxygen species are common stressors of cellular live and are the cause of many human health problems such as mental disorder, inflammatory disease and numerous cancers. Plants and microorganisms are vulnerable to the same chemical stressors, but some of these species have acquired remarkable resilience that allows them to strife under very hostile conditions. Elucidation of the underlying mechanisms may provide novel strategies for therapeutic interventions in metal- or redox-induced medical disorders. Sulfur and selenium containing small molecules are key components of cellular defence systems against chemical stress. Microbial resistance to extreme stress often relies on unusual small molecules with remarkable properties. In this project we will investigate the biosynthetic origin and physiological role of a seleno-compound produced by the plant associated bacterium Variovorax paradoxus . This metabolite is also present in humans, but its physiological effects are largely unknown