Horizontal transfer of bacterial heavy metal resistance genes and its applications in activated sludge systems

Abstract

The bacterial nickel (Ni) resistance determinant ncc-nre of Alcaligenes 31A strain cloned to an IncQ broadhost-range plasmid pKT240 gave rise to pMOL222. The plasmid was subsequently mobilized into various Eubacteria and found to confer an increased Ni resistance on these recipients. An increase of Ni resistance was also observed after the transfer of pMOL222 into activated sludge bacteria by plate mating. The dissemination of pMOL222 into an activated sludge pilot stabilized the system during a heavy metal shock loading with 0.25 mM Ni.