FIG 2.

Ectopic csrA paralog expression reduces ICE transfer. The ICE-βox-null recipient strain (MB370) was mated with the following ICE-βox⁺ donor strains (white bars): ΔcsrT strain (MB1507), WT with no csr plasmid (MB1353), WT with pcsrT (MB1465), and WT with pcsrA-22 (MB1499). MB370 was also mated with the following LpgGI-1⁺ donor strains (gray bars): WT with pcsrT (MB1500) and WT with pcsrA-22 (MB1501). The strains were cultured prior to mating without (−) or with (+) IPTG to induce ectopic expression of CsrT. Mean transconjugation efficiency of the ICEs is expressed as (CFU_{transconjugants}/CFU_donor) ± the SEM of results from one representative of two independent experiments performed at least in duplicate. A Student t test was used to show whether the difference between uninduced and induced transconjugation efficiency was statistically significant (*, P < 0.05).