Figure 2. Growth in vitro.

Indicated bacterial strains were grown at 37°C, 200 rpm for 16 hrs in either LB or M9 before sub-culturing into fresh media at a 40 fold dilution (LB or M9), and growth was followed every 15 min for 18 hrs using a Bioscreen C. Where indicated, the M9 was supplemented with either 100 µg ml⁻¹ of putrescine or spermidine, respectively, during the growth experiment.