FIG. 4.

Stabilizing pSW140K by plasmids that carry traC. E. coli DT-5(pSW140K), an E. coli HB101 mutant that contains mutated traC (empty squares), was transformed with pF101 (filled squares) and pML12 (empty circles) to determine how traC affected the stability of pSW140K, which was also tested in E. coli HB101 (filled diamonds), E. coli DH5α (empty triangles), and E. coli DH5α(pF101) (filled triangles). Cells were initially cultured in LB-Km broth and then subcultured in LB or LB-Am broth for 84 generations. Nonpigmented colonies on LB or LB-Am agar, indicating the loss of pSW140K, were counted.