Figure 7.
Effect of the velocity of plasmid repopulation on the segregational stability of an incoming plasmid. Two extreme theoretical cases of immediate (A) or null (B) plasmid repopulation are displayed. These models assume that the plasmid does not burden the host cell. We defined “Pn” as the fraction of transformants after n generations; “a” is the initial number of transformants, and “b” is the number of non-transformed cells within the total bacterial population. In the case that immediate repopulation occurs (A), the steady-state plasmid copy number is reached before division of the transformants, and the plasmid is stably inherited to both daughter cells. Dotted circles in (A) represent the number of new plasmid molecules generated in each cell generation. If no repopulation occurs (B), the single, unreplicated plasmid copy is inherited by only one of the two daughter cells resulting from division of the transformants, giving rise to maximal segregational instability.