title: Adsorption kinetics of Pb and Cd by two plant growth promoting rhizobacteria.
abstract: A bench study was carried out to characterize the kinetics of two plant growth promoting rhizobacteria (PGPR) Azotobacter chroococcum and Bacillus megaterium to adsorb heavy metals from solution. Adsorption of Pb(2+) and Cd(2+) by bacterial cells was processed quickly with an equilibration achieved within 5 min. The adsorptions were fitted well with Freundlich and Langmuir isotherm models. The comparison of isotherm parameters indicated that A. chroococcum had a stronger capacity to bind metal ions than B. megaterium, with an average increase of 59.8% for Pb(2+) and 75.6% for Cd(2+), respectively. Both bacteria had a stronger affinity to Pb(2+) than Cd(2+) since Pb(2+) was more easily bound with the phosphoryl groups on the cell surface than Cd(2+). This demonstrated that the presence of bacteria in the rhizosphere may result in the reduction of mobile ions in soil solution.
authors.affiliation: Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Hong Kong, PR China.
authors.forename: S C
authors.initials: SC
authors.lastname: Wu
authors.forename: X L
authors.initials: XL
authors.lastname: Peng
authors.forename: K C
authors.initials: KC
authors.lastname: Cheung
authors.forename: S L
authors.initials: SL
authors.lastname: Liu
authors.forename: M H
authors.initials: MH
authors.lastname: Wong
mesh_terms: D000327:Adsorption; D001410:Bacillus megaterium / Q000166:cytology / Q000378:metabolism; D002104:Cadmium / Q000378:metabolism*; D007700:Kinetics; D007854:Lead / Q000378:metabolism*; D063245:Plant Development; D010944:Plants / Q000382:microbiology*; D012231:Rhizobium / Q000166:cytology / Q000378:metabolism*; D012996:Solutions; D013997:Time Factors
chemical_list: D012996:Solutions; D002104:Cadmium; D007854:Lead