Conjugative plasmid mediated inducible nickel resistance in Hafnia alvei 5-5

Authors

  • Jeong Eun Park Department of Biology, Research Institute for Basic Science, Kyunghee University, Seoul, Korea
  • Kho Eun Young Department of Biology, Research Institute for Basic Science, Kyunghee University, Seoul, Korea
  • Hans-Günter Schlegel Institut für Mikrobiologie, Georg-August-Universität, Göttingen, Germany
  • Ho Gun Rhie Department of Biology, Research Institute for Basic Science, Kyunghee University, Seoul, Korea
  • Ho Sa Lee Department of Biology, Research Institute for Basic Science, Kyunghee University, Seoul, Korea

Keywords:

transconjugant, nickel-resistant bacteria, inducible nickel resistance, TnphoA´-1 insertion mutagenesis

Abstract

Hafnia alvei 5-5, isolated from a soil-litter mixture underneath the canopy of the nickel-hyperaccumulating tree Sebertia acuminata (Sapotaceae) in New Caledonia, was found to be resistant to 30 mM Ni2+ or 2 mM Co2+. The 70-kb plasmid, pEJH 501, was transferred by conjugation to Escherichia coli, Serratia marcescens, and Klebsiella oxytoca. Transconjugant strains expressed inducible nickel resistance to between 5 and 17 mM Ni2+, and cobalt resistance to 2 mM Co2+. A 4.8-kb Sal–EcoRI fragment containing the nickel resistance determinant was subcloned, and the hybrid plasmid was found to confer a moderate level of resistance to nickel (7 mM Ni2+) even to E. coli. The expression of nickel resistance was inducible by exposure to nickel chloride at a concentration as low as 0.5 mM Ni2+. By random TnphoA´-1 insertion mutagenesis, the fragment was shown to have structural genes as well as regulatory regions for nickel resistance. Southern hybridization studies showed that the nickel-resistance determinant from pEJH501 of H. alvei 5-5 was homologous to that of pTOM9 from Alcaligenes xylosoxydans 31A.

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Published

2010-03-09

Issue

Section

Research Articles