Highlights of nitrogen fixation research

At the present time, the precise taxonomial status of many strains classified as #Bradyrhizobium$ still remains unclear. There is a need to develop a reliable grouping method, specifying the genetic relationships between these strains. Phenotypic methods as auxanography or protein profiling did not prove valuable for classification of bradyrhizobia and were not in good agreement with phylogenetic data. The purpose of this work is to develop a strategy to analyse the diversity of bradyrhizobia and to identify genomic groups among our collection of strains isolated from 9 small legume species in Senegal. #B. japonicum$, #B. elkanii$ and representatives of previously described groups by Moreira et al. (1993) and Dupuy et al. (1994) were included as references. Bacterial diversity was assessed by two different techniques, PCR-RFLP analysis of the IGS region between 16S and 23S rDNA (IGS) and the AFLP technique. Groupings of strains obtained by the two methodologies will be presented and compared. 16S rDNA PCR-RFLP analysis of strains representative of IGS clusters from small legumes was also performed. (Résumé d'auteur