Figure 1.

Model flow. Bacteria are indicated by borders; dashed borders indicate that the state can change, solid is permanent (because the model does not extend to lysis of infected cells). Letters inside the borders indicate the contents. B = bacteria, P_i indicates phage type i, where i = 1, 2. Uninfected bacteria can only become singly infected at a given instant. Singly infected bacteria can move into a state of permanent single infection (rate δ) or be subject to coinfection. The adsorption rate constant (k) influences the rate at which bacteria become infected, independent of whether they were previously infected. These assumptions are for modeling convenience but should be suitable approximations for many empirical systems.