The use of alternative energies as fuel and the protection of arable soils as resource for food crop are of major concern in the current context of deficiency of fertile soils. Thus, the main aim of this thesis was to study the potential adaptation of the bioenergetic plant Miscanthus x giganteus on soils highly contaminated by metals and metalloids, and unsuitable for food crops. The experimental site is a former mine located in Limousin (France) where gold treatment induced heavily contaminated tailings, in the sixties. The vegetation cover is nowadays developing. The culture clearly highlighted adaptation capacities of the plant with a low transfer of potentially toxic elements even though soils were acidic, exceptionally contaminated (till 83000 mg As.kg-1, 15000 mg Pb.kg-1 and 1100 mg Sb.kg-1) and with low agronomic performances. Moreover, bioavailability represented only 1 to 5% of total concentrations according to the used reactant which corresponded to very high amounts, given values of total concentrations. These findings are directly link to the mineralogy of the site. M. x giganteus responded to metallic stress with a strong reduction of biomass yield, a slight disturbance of net photosynthesis rate and a reduction of stomatal conductance and substomatal CO2 concentration. Furthermore, the plant modified the potential activity of rhizospheric ammonia oxidizing bacteria and archaea involved in nitrification. As expected, the more the contamination was high the more M. x giganteus response was marked. Despite a clear reduced As, Sb and Pb transfer to aerial parts, values of measured concentrations could not allow an industrial revalorization. However, this plant could stabilize the soil. Agronomic improvements of the soil might enhance yields for an industrial revalorization.
