Abstract: The competition between edible ectomycorrhizal fungi ( EMF) and other ectomycorrhizal fungi have been studied in greenhouse and in the field taking into account different environmental conditions and using molecular tools as well as morphological methods . Approximately 100 ectomycorrhizal species were identified in soil fungal communities in productive areas of Boletus edulis sensu lato and in truffières of Tuber magnatum and Tuber borchii . The bacterial communities occurring in T. magnatum and T. borchii fruiting bodies during different stages of their maturation were also characterized. α- Proteobacteria, were found as major constituents of the bacterial community associated with truffle ascoma , independentely of the degree of maturation. These bacteria include members of the Sinorhizobium􊄯 Ensifer and Rhizobium􊄯Agrobacterium groups, and Bradyrhizobium spp ., which are well known for their ability to fix atmospheric nitrogen. Our studies raise two important questions about truffle biology: 1 ) can the composition of microbial soil communities infuence EMF fruiting body production ?2) can nitrogen fixing bacteria play a role in truffle nutrition ?

Key words: Edible ectomycorrizal fungi communities