Figure 4: The persistence of Y. pestis (♦), Panels A and C, and Y. enterocolitica (♦), Panel B, were determined while simultaneously monitoring for H. gracilis (■) outgrowth. Initial inoculating concentrations were 5 x 106 CFU/mL (Panels A and B), 50 CFU/mL (Panel C), and 500 CFU/mL (Panel D). The dotted line in Panel A depicts where the number of CFUs/mL of H. gracilis were too numerous to count. No standard deviations were calculated as these data were generated from triplicate platings of a single microcosm.