FIG 3.
The BdAU0158 bcp-3 locus encodes a functional CDI system that is not expressed under in vitro competition conditions. (A) β-Galactosidase activity assays for promoters of the BdAU0158 bcp-1, bcp-2, and bcp-3 loci. A BdAU0158 strain harboring a constitutively expressed lacZ reporter (PS12-lacZ) served as a positive control, whereas a BdAU0158 strain harboring a lacZ reporter without a promoter (promoterless) served as a negative control. (B) Competition assays between BdAU0158 bcp-3C inhibitor cells and Δbcp-3, Δbcp-3 attTn7::bcpI-3, and WT target cells. The dotted line (log10 C.I. = 0) indicates no competitive advantage for inhibitor or target strain. The red-filled circle indicates a competition from which no target cells were recovered following 48 h of coculture. (C) β-Galactosidase activity assays for the BdAU0158 Pbcp-3 reporter strain cocultured with BdAU0158 bcp-3C (bcp-3C versus Pbcp-3-lacZ), as well as the BdAU0158 PbcpI-3 reporter strain (PbcpI-3-lacZ), with PS12-lacZ and promoterless positive and negative controls, respectively, as described for panel A. β-Galactosidase activity assays in panels A and C show results from two biological replicates, each with three technical replicates. ***, P < 0.001; ****, P < 0.0001, unpaired t test. Competition assays in in panel B show results from three biological replicates, each with three technical replicates. Solid horizontal lines represent mean log10 C.I. values. ****, P < 0.0001, Mann-Whitney test.