FIG 2.

OmpF is important in the recognition of E. coli but not for other prey species. (a) Loss of OmpF in various E. coli strains inhibited predation by B. bacteriovorus strain 109J. The prey strains evaluated included both K-12 and B strains of E. coli. Statistical significance was determined against the wild-type response. ns, not significant; b, P < 0.01; c, P < 0.001. Error bars show SD (n = 3). (b) Loss of OmpF or its homologues had varied impacts with other prey species. Within both E. fergusonii and S. enterica, the loss of OmpF had no obvious impact, while for K. pneumoniae, it depended on the strain. While the predation rates were identical for K. pneumoniae strain WGLW1 (HM-750) and its isogenic ompK35 knockout mutant, loss of the ompK35 gene in K. pneumoniae strain WGLW2 (HM-751) delayed predation of this pathogen by B. bacteriovorus 109J. Statistical significance was determined against the wild-type response. ns, not significant; a, P < 0.05. Error bars show SD (n = 3). (c) Loss of OmpF in E. coli BW25113 impacts its predation by various Bdellovibrio strains. Six different Bdellovibrio strains were evaluated, including two new isolates obtained from a wastewater treatment plant (strains EY2.3 and EY 3.3) and two from forest soil (strains DH1 and SM1). In each case, the absence of OmpF significantly delayed predation. Statistical significance was determined against the wild-type response. a, P < 0.05; c, P < 0.001. Error bars show SD (n = 3).