title: Construction and characterization of a photosynthetic bacterium genetically engineered for Hg2+ uptake.
abstract: A recombinant photosynthetic bacterium, Rhodopseudomonas palustris, was constructed to simultaneously express mercury transport system and metallothionein for Hg(2+) removal from heavy metal wastewater. The effects of essential process parameters, including pH, ionic strength and presence of co-ions on Hg(2+) uptake were evaluated. The results showed that compared with wild type R. palustris, recombinant strain displayed stronger resistance to toxic Hg(2+), and its Hg(2+) binding capacity was enhanced threefolds. In the range of pH 4-10, recombinant R. palustris maintained effective accumulation of Hg(2+). The presence of 10 mg L(-1) Mg(2+), Ca(2+), Zn(2+) or Ni(2+) did not significantly influence Hg(2+) bioaccumulation by recombinant R. palustris from solutions containing 0.2 mg L(-1) Hg(2+), while Na(+) and Cd(2+) posed serious adverse effect on Hg(2+) uptake. Furthermore, EDTA treatment experiment confirmed that different from wild type R. palustris that mainly absorbed Hg(2+) on the cell surface, recombinant R. palustris transported most of the bound Hg(2+) into the cells.
authors.affiliation: College of Life Sciences, Shenzhen University, Shenzhen, PR China. dengxu@szu.edu.cn
authors.forename: Xu
authors.initials: X
authors.lastname: Deng
authors.forename: Pei
authors.initials: P
authors.lastname: Jia
mesh_terms: D001673:Biodegradation, Environmental; D024861:Genetic Enhancement / Q000379:methods*; D008027:Light; D008628:Mercury / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology; D012241:Rhodopseudomonas / Q000502:physiology* / Q000528:radiation effects; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D018508:Water Purification / Q000379:methods*
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury