Virulence of <i>K. pneumoniae</i> against <i>D. discoideum</i> can be modulated.

<p>(A) The ability of <i>Dictyostelium</i> to grow on a bacterial lawn was assessed by depositing amoebae (from 10 to 10,000) on a lawn of bacteria grown on SM agar medium. A phagocytosis plaque was observed 5 days later when bacteria were permissive. Bacteria tested were: <i>K. pneumoniae</i> (Kp52145), <i>cps</i> mutant (52145-<i>Δwca</i>_K2; <i>Δwca</i>_K2), or control strain (<i>K. aerogenes</i>). (B) The ability of wild-type <i>K. pneumoniae</i> (Kp52145), <i>cps</i> mutant (52145-Δ<i>wca</i>_K2), or control strain (<i>K. aerogenes</i>) to resist predation by <i>D. discoideum</i> was tested on HL5-agar, pure or diluted. 1,000 amoebae were deposited on the bacterial lawns and plaques were recorded 5 days later. (C) The ability of <i>Dictyostelium</i> to grow on a bacterial lawn was assessed by depositing amoebae (from 10 to 10,000) on a lawn of bacteria grown on HL5–5% agar medium. A phagocytosis plaque was observed 5 days later when bacteria were permissive (<i>K. aerogenes</i> and 52145-Δ<i>wca</i>_K2; <i>Δwca</i>_K2).