Figure 2.

Predation Experimentally Measured and Modelled in Ca/HEPES buffer. (a) Graphs show individual biological repeats- separate experiments (Expt) of the live bacterial counts from predation in buffer experiments, results from each individual biological experiment are represented by the same colour line on each graph. Changes in the population of both K. pneumoniae prey (Kp + HD100) and B. bacteriovorus HD100 predator (HD100 + Kp) were enumerated periodically during the predation assay. As a control, prey suspended in Ca/HEPES was enumerated periodically in the absence of B. bacteriovorus HD100 predator (Kp alone). (b) Prey concentration (green line) initially shows a 6 log₁₀ reduction by 6 hours (see inset) before regrowth overtakes predation effects. Predator concentration (orange line) grows in line with the prey death for the first six hours then reduces, in line with experimental results. Experimental results reproduced from A shown as a bar plot, the model simulation lies within the error bars of the experimental results. (c) Model simulation results showing prey with a predator attached (PBD_O), prey with a predator inside (PBD_I) and inactivated predators (BD_I) over time. Attachment drops off after 5 hours due to prey becoming resistant.(d) Model simulation of waste accumulation over time. Non-degradable waste increases monotonically leading to prey resistance whilst nutritious waste initially increases but is then depleted as it is used by the growing predominently resistant prey. Parameter values and further model validation are detailed in supplementary material. The model gives a good fit to the experimental data.