title: Cr-resistant rhizo- and endophytic bacteria associated with Prosopis juliflora and their potential as phytoremediation enhancing agents in metal-degraded soils.
abstract: Prosopis juliflora is characterized by distinct and profuse growth even in nutritionally poor soil and environmentally stressed conditions and is believed to harbor some novel heavy metal-resistant bacteria in the rhizosphere and endosphere. This study was performed to isolate and characterize Cr-resistant bacteria from the rhizosphere and endosphere of P. juliflora growing on the tannery effluent contaminated soil. A total of 5 and 21 bacterial strains were isolated from the rhizosphere and endosphere, respectively, and were shown to tolerate Cr up to 3000 mg l(-1). These isolates also exhibited tolerance to other toxic heavy metals such as, Cd, Cu, Pb, and Zn, and high concentration (174 g l(-1)) of NaCl. Moreover, most of the isolated bacterial strains showed one or more plant growth-promoting activities. The phylogenetic analysis of the 16S rRNA gene showed that the predominant species included Bacillus, Staphylococcus and Aerococcus. As far as we know, this is the first report analyzing rhizo- and endophytic bacterial communities associated with P. juliflora growing on the tannery effluent contaminated soil. The inoculation of three isolates to ryegrass (Lolium multiflorum L.) improved plant growth and heavy metal removal from the tannery effluent contaminated soil suggesting that these bacteria could enhance the establishment of the plant in contaminated soil and also improve the efficiency of phytoremediation of heavy metal-degraded soils.
authors.affiliation: Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering Faisalabad, Pakistan.
authors.forename: Muhammad U
authors.initials: MU
authors.lastname: Khan
authors.affiliation: Bioresources Unit, Austrian Institute of Technology GmbH Tulln, Austria.
authors.forename: Angela
authors.initials: A
authors.lastname: Sessitsch
authors.affiliation: Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering Faisalabad, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Harris
authors.affiliation: Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering Faisalabad, Pakistan.
authors.forename: Kaneez
authors.initials: K
authors.lastname: Fatima
authors.affiliation: Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering Faisalabad, Pakistan.
authors.forename: Asma
authors.initials: A
authors.lastname: Imran
authors.affiliation: Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering Faisalabad, Pakistan ; Earth Sciences Department, King Fahd University of Petroleum and Minerals Dhahran, Saudi Arabia.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Arslan
authors.affiliation: Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering Faisalabad, Pakistan.
authors.forename: Ghulam
authors.initials: G
authors.lastname: Shabir
authors.affiliation: Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering Faisalabad, Pakistan.
authors.forename: Qaiser M
authors.initials: QM
authors.lastname: Khan
authors.affiliation: Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering Faisalabad, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Afzal
keywords: Cr-resistant bacteria; Prosopis juliflora; endophytic bacteria; heavy metals; phytoremediation; plant growth-promoting bacteria; rhizobacteria