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Several arsenic compound-resistant bacteria were isolated from Jung-Rang stream. The isolates, D-3, D-12, and D-14 were characterized phenotypically and genetically, and identified as Serratia liquefaciens, KkbsieUa oxytoca, and KkbsieUa pneumoniae, respectively. A plasmid of 67 kb was found in Kkbsiella oxytoca D-12 and designated as pMH12. Transfer of this plasmid from D-12 to E coli HB101 was occurred, and the resulting transconjugant strains expressed the same level of heavy metal resistance as the donor strain. The physical presence of this plasmid in transconjugant was detected with agarose gel electrophoresis. Arsenite-sensitive derivatives of isolate D-12 were obtained with Mitomycin C treatment which cured pMH12. Antibiotics and heavy metal resistances were also examined to be used as a proper marker for the isolates in gene cloning. Isolate D-12 has resistance to several heavy metal ions such as Cd2+, Zn2+, and He´. Also, all the other arsenite resistant isolates showed resistance to several heavy metal ions and antibiotics.
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