TABLE 1.

Plasmid content of B. burgdorferi B31 clones derived after serial passages at 35°C

PassageaColony morphologybPlasmid(s) lostc
P1.1 derivedP1.6 derived
3Dcp9, lp21, lp25cp9
Elp28-4
Fcp9, lp25
6Ecp9, lp28-4
Fcp9, lp28-1, lp28-4
9ENEd
F
13E
Flp28-4
16D
E
Flp17, lp25
19Elp28-4cp9
F
22E
Flp17, lp25, lp28-2
25Ecp9cp9, lp21, lp28-4
Flp28-4cp9, lp21
  • a One passage represents a 1:500 dilution of a late-exponential-phase culture to 1 × 105 to 5 × 105 cells/ml after ca. 3 days of growth at 35°C.

  • b Representative clones were chosen on the basis of their differing colony morphologies. D, tiny, dense, defined border; E, small, dense center, defined border; F, large, diffuse, no defined border.

  • c Plasmid content was assessed by PCR of individual clones derived from P1.1 and P1.6 clones after the indicated number of passages, as described in Materials and Methods. Plasmids that were not detected by PCR are listed. Dashes indicate that a PCR product was obtained for all plasmids.

  • d NE, nonexistent. Plating of this passage resulted in colonies that all showed morphology F; no colonies with morphology E were obtained.