Рopulation dynamics of bacterial plasmids

We suggest a new mathematical model of population dynamics of bacterial plasmids which accounts for the presence of several plasmid copies in a particular cell. We found that a decrease of the average number of plasmids in the population of bacteria is exponential with a rate that is lower than predicted by previous models. We developed a model based characteristic that is a time of elimination of plasmids from the chemostat culture. The time is defined by the generation time in chemostat, the rate of plasmid loss and selection coefficient (“cost” of the plasmid). Model allowed us to explain the effect of decreasing the selection coefficient during prolonged cultivation of recombinant bacteria in chemostat connected (in the model) to the declining the average plasmid copy number in the microbe population.