title: Taxonomic and symbiotic diversity of bacteria isolated from nodules of  Acacia tortilis  subsp. raddiana in arid soils of Tunisia.
abstract: A collection of rhizobia isolated from Acacia tortilis subsp. raddiana nodules from various arid soils in Tunisia was analyzed for their diversity at both taxonomic and symbiotic levels. The isolates were found to be phenotypically diverse. The majority of the isolates tolerated 3% NaCl and grew at 40 °C. Genetic characterization emphasized that most of the strains (42/50) belong to the genus Ensifer, particularly the species Ensifer meliloti, Ensifer garamanticus, and Ensifer numidicus. Symbiotic properties of isolates showed diversity in their capacity to nodulate their host plant and to fix atmospheric nitrogen. The most effective isolates were closely related to E. garamanticus. Nodulation tests showed that 3 strains belonging to Mesorhizobium genus failed to renodulate their host plant, which is surprising for symbiotic rhizobia. Furthermore, our results support the presence of non-nodulating endophytic bacteria belonging to the Acinetobacter genus in legume nodules.
authors.affiliation: Laboratoire de biotechnologies végétales appliquées à l'amélioration des cultures, Faculté des sciences de Gabès, Université de Gabès, Cité Erriadh, Zrig 6072 Gabès, Tunisia.
authors.forename: A
authors.initials: A
authors.lastname: Fterich
authors.forename: M
authors.initials: M
authors.lastname: Mahdhi
authors.forename: A
authors.initials: A
authors.lastname: Lafuente
authors.forename: E
authors.initials: E
authors.lastname: Pajuelo
authors.forename: M A
authors.initials: MA
authors.lastname: Caviedes
authors.forename: I D
authors.initials: ID
authors.lastname: Rodriguez-Llorente
authors.forename: M
authors.initials: M
authors.lastname: Mars
mesh_terms: D000045:Acacia / Q000382:microbiology*; D010802:Phylogeny; D012231:Rhizobium / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D016962:Sinorhizobium meliloti / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D013559:Symbiosis; D014416:Tunisia
chemical_list: D012987:Soil