Relative levels of c-di-GMP in matched cell biomass wild-type predatory cultures of HD100 strain, silent Bd1971 deletion strain (Δ1971), Bd1971D306307A strain (bd1971DD) and Bd1971R67D strain (bd1971R). All mutant strains had higher levels of c-di-GMP compared to the wild type strain. Error bars show SEM. Data are from six independent experiments for HD100 and ΔBd1971 and from four independent experiments for Bd1971DD and Bd1971R mutants. 