Résumé
Five species of Acacia (Acacia ehrenbergiana Hayne, A. nilotica (L.) Delile, A. seyal Delile, A. tortilis(Forssk.) Hayne and A. laeta Delile) indigenous to Tamanrasset (Algeria) were investigated for theirnodulation status and nodular endophytic diversity. A. ehrenbergiana showed the highest nodulationability across the different sites in this region, indicating the widespread occurrence of compatiblerhizobia in the soils. Altogether 81 strains were purified. Among this endophytic strain collection, onlyfour bacterial endophytes nodulated their respective host plants. On the basis of partial 16S rDNAsequencing, they were affiliated to Ensifer sp., Ensifer teranga, Mesorhizobium sp. and Rhizobium sp.Among the 79 non- symbiotic endophytes, 24 representative strains on the basis of PCR-RFLP profileobtained with MSPI enzyme digestion were characterized. They belonged to nine genera, namely: Paenibacillus, Ochrobactrum, Stenotrophomonas, Pseudomonas, Microbacterium, Rhizobium,Agrobacterium, Brevibacillus and Advenella. The isolated nodular endophytes in this study revealed astrong tolerance profile to salinity and high temperature. Principal component analysis confirmed thatno correlation was found between bacterial tolerance to a maximum temperature of growth and soildepth of sampling. This tolerance profile was distributed over the three levels of soil depth sampling:20, 40 and 60 cm. On the other hand, there was no relationship between in vitro tolerances of rhizobialstrains to NaCl and high temperature and corresponding edaphoclimatic characteristics of the samplingsites. This study is a contribution to nodular bacterial diversity knowledge of desert African Acaciaspecies growing in preserved ecosystems.