Stability of the pSW100 replicon in E. coli strains. E. coli strains HB101(pSW100K), HB101(pSW140K), and MG1063(pSW140K) (circles with an empty diamond), DH5α(pSW100K) (filled triangles), DH5α(pSW140K) (filled squares), ATCC 25257(pSW140K) (filled diamonds), ATCC 25256(pSW140K) (empty circles), ATCC 23744(pSW140K) (empty squares), and ATCC 23846(pSW140K) (squares with a cross) were cultured in LB-Km broth overnight and subcultured in LB broth with an inoculation size of 1% for 84 generations. Cells were plated on LB agar after every 14 generations of culturing. The percentages of the colonies that had lost their orange color, indicating the loss of pSW140K, were calculated. The stability of pSW100K was examined by replica plating the cells on LB and LB-Km agar.