A Monte Carlo simulation of plasmid replication during the bacterial division cycle

Plasmids have cell cycle replication patterns that need to be considered in models of their replication dynamics. To compare current theories for control of plasmid replication with experimental data for timing of plasmid replication with the cell cycle, a Monte Carlo simulation of plasmid replication and partition was developed. High‐copy plasmid replication was simulated by incorporating equations previously developed from the known molecular biology of ColE1‐type plasmids into the cell‐cycle simulation. Two types of molecular mechanisms for low‐copy plasmid replication were tested: accumulation of an initiator protein in proportion to cell mass and binding of the plasmid origin to the cell membrane. The low‐copy plasmids were partitioned actively, with a specific mechanism to mediate the transfer from mother to daughter cells, whereas the high‐copy plasmids were partitioned passively with cell mass.