title: Identification of effective Pb resistant bacteria isolated from Lens culinaris growing in lead contaminated soils.
abstract: Soil bacteria are a new phytoremediation system for the removal of heavy metals from soils. In this study, fifteen soil bacteria were isolated from root nodules of lentil growing in heavy metals contaminated soils, particularly by lead. Molecular characterization of the collection showed a large diversity, including Agrobacterium tumefaciens, Rahnella aquatilis, Pseudomonas, and Rhizobium sp. These soil bacteria had a wide range of tolerance to heavy metals. Among them, strains of A. tumefaciens and R. aquatilis tolerated up to 3.35 mM Pb; whereas Pseudomonas tolerated up to 3.24 mM Pb. The inoculation of lentil grown hydroponically with inoculums formed by these efficient and Pb resistant bacteria enhanced plant biomass. The treatment of this symbiosis by 1 mM Pb for 10 days or by 2 mM Pb for 3 days demonstrated that lentil had Pb accumulation capacity and can be considered a Pb accumulator plant, elsewhere, roots accumulated more Pb than shoots, and the inoculation decreased the Pb up take by the plants, suggesting that this symbiosis should be investigated for use in phytostabilization of Pb-contaminated soils. At the same time, a modulation in the antioxidant enzyme activity and a specific duration was required for the induction of the superoxide dismutase (SOD), peroxidase (POX), and ascorbate peroxidase (APX) response and to adapt to Pb stress. These results suggested that these enzymes may be involved in the main mechanism of antioxidative defense in lentil exposed to Pb oxidative stress.
authors.affiliation: University Tunis El Manar, Centre de Biotechnologie Borj Cedria, Laboratoire des Légumineuses, Hammam Lif, Tunisie.
authors.forename: Salwa Harzalli
authors.initials: SH
authors.lastname: Jebara
authors.forename: Souhir
authors.initials: S
authors.lastname: Abdelkerim
authors.forename: Imen Challougui
authors.initials: IC
authors.lastname: Fatnassi
authors.forename: Manel
authors.initials: M
authors.lastname: Chiboub
authors.forename: Omar
authors.initials: O
authors.lastname: Saadani
authors.forename: Moez
authors.initials: M
authors.lastname: Jebara
mesh_terms: D016960:Agrobacterium tumefaciens / Q000302:isolation & purification; D001419:Bacteria / Q000187:drug effects* / Q000302:isolation & purification*; D001673:Biodegradation, Environmental; D018533:Biomass; D002104:Cadmium / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D018527:Hydroponics; D007854:Lead / Q000378:metabolism* / Q000494:pharmacology*; D027806:Lens Plant / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology*; D018384:Oxidative Stress; D010544:Peroxidases / Q000378:metabolism; D018517:Plant Roots / Q000737:chemistry / Q000201:enzymology / Q000382:microbiology; D011549:Pseudomonas / Q000302:isolation & purification; D020638:Rahnella / Q000302:isolation & purification; D012231:Rhizobium / Q000302:isolation & purification; D053204:Root Nodules, Plant / Q000737:chemistry / Q000201:enzymology / Q000382:microbiology; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D007854:Lead; D010544:Peroxidases; D013482:Superoxide Dismutase
keywords: Rhizobium; heavy metals; lead; lentil; soil bacteria