Reduced virulence in <i>V. cholerae</i> Δ<i>ybeY</i>.

<p><b>A</b>) Depletion of YbeY leads to a deficiency of pigment formation. C6706 Wt pY and Δ<i>ybeY</i> pY cells were grown in LB medium in the presence of arabinose or glucose as indicated. When cells reached mid to late-log phase, a similar number of cells was spun down and the cell pellets were photographed. <b>B</b>) Depletion of YbeY results in a drastic decrease of biofilm formation in C6706 Δ<i>ybeY</i> pY cells. Cultures were grown statically in LB medium supplemented with arabinose or glucose as indicated. <b>C</b>) Depletion of YbeY leads to reduced levels of cholera toxin (CT). C6706 Wt pY and Δ<i>ybeY</i> pY cells were grown in LB medium in the presence of arabinose or glucose. The amount of CT was estimated in the supernatants of cultures by western blot analysis using a CT-specific antibody. Equivalent amounts of protein were applied per lane. <b>D</b>) Depletion of YbeY leads to sensitivity towards bile salts. C6706 Wt and Δ<i>ybeY</i> pY cells were grown in LB medium supplemented with 2.0% of bile salts and arabinose as specified. Samples were taken at the indicated times, and the number of colony forming units (CFU) was determined. <b>E</b>) Depletion of YbeY leads to reduced colonization of intestines in infant mice. Competitive indexes show the ability of C6706 Δ<i>ybeY</i> pY cells to colonize the infant mouse intestine relative to C6706 Wt and equal 1 upon full complementation. C6706 Δ<i>ybeY</i> pY cells were grown in the presence or absence of arabinose as indicated.