A discrete, size-structured chemostat model of plasmid-bearing and plasmid-free competition

A discrete-time, discrete size-structured model of plasmid-bearing and plasmid-free competition in the chemostat is proposed and analyzed. It is assumed that both populations have the same number of size classes with approximately the same newborn biomass and cells divide when they double their size. As in the continuous-time model, it is impossible to have only the plasmid-bearing organism in the chemostat. Moreover, both populations can coexist with each other if the break-even nutrient concentration of the plasmid-bearing population is less than that of the plasmid-free population.