10.
Summary
Escherichia coli Rl is an Ag
+-resistant strain that, as we have shown recently, harbours at least two large plasmids, pJT1 (83 kb) and pJT2 (77 kb). Tn5-Mob was introduced into the
E. coli Rl host replicon via conjugation on membrane filters. The transfer functions of plasmid RP4-4 were provided in this process and Tn5-Mob clones mated with
E. coli C600 yielded Ag
+-resistant transconjugants. This mobilization procedure allowed transfer and expression of pJT1 Ag
+ resistance in
E. coli C600. Prior to use of Tn5-Mob mobilization, it was not possible to transfer Ag
+-resistant determinant(s) into
E. coli by conjugation or transformation including high-voltage electroporation.
E. coli C600 containing PJTI and PJT2 displayed decreased accumulation of Ag
+ similar to
E. coli R1.
E. coli C600 could not tolerate 0.1 and 0.5 mM Ag
+, rapidly accumulated Ag
+ and became non-viable. Tn5-Mob mobilization may be useful in the study of metal resistance in bacteria, especially in strains not studied for resistance mechanisms.
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