title: Osmoadaptative responses in the rhizobia nodulating Acacia isolated from south-eastern Moroccan Sahara.
abstract: Four strains of rhizobia nodulating Acacia were isolated from the Moroccan desert soil by trapping with seedlings of Acacia gummifera and Acacia raddiana, and were studied for their ability to tolerate high salinity and dryness conditions. The strains MDSMC 2, MDSMC 18 and MDSMC 50 were halotolerant (they tolerated up to 1 M NaCl) and they accumulated glutamate and mannosucrose. The synthesis of the latter solute, which is the major endogenous osmolyte, is partially repressed in the presence of glycine betaine. The strain MDSMC 34 was less halotolerant (growth inhibited by a concentration greater than 0.5 M NaCl), and accumulated trehalose (as the main endogenous osmolyte) and glutamate. Rhizobia from the Moroccan desert soil were highly resistant to desiccation and their tolerance to dryness was stimulated by osmotic pretreatment. Thus, the accumulation of mannosucrose or trehalose by desert rhizobia represents both an osmoadaptative response and a part of a desiccation tolerance mechanism.
authors.affiliation: Departement Osmorégulation chez les Bactéries, UMR-CNRS 6026, IFR 140, Université de Rennes 1, Campus de Beaulieu, Av. du Général Leclerc, 35042 Rennes, France.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Essendoubi
authors.forename: Fatiha
authors.initials: F
authors.lastname: Brhada
authors.forename: Jamal Eddine
authors.initials: JE
authors.lastname: Eljamali
authors.forename: Abdelkarim
authors.initials: A
authors.lastname: Filali-Maltouf
authors.forename: Sylvie
authors.initials: S
authors.lastname: Bonnassie
authors.forename: Sylvie
authors.initials: S
authors.lastname: Georgeault
authors.forename: Carlos
authors.initials: C
authors.lastname: Blanco
authors.forename: Mohamed
authors.initials: M
authors.lastname: Jebbar
mesh_terms: D000045:Acacia / Q000145:classification / Q000382:microbiology*; D000222:Adaptation, Physiological; D003889:Desert Climate; D003890:Desiccation; D018698:Glutamic Acid / Q000378:metabolism; D018869:Heat-Shock Response; D009018:Morocco; D009994:Osmolar Concentration; D012231:Rhizobium / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology*; D012988:Soil Microbiology; D014199:Trehalose / Q000378:metabolism
chemical_list: D018698:Glutamic Acid; D012965:Sodium Chloride; D014199:Trehalose