(A) Analysis of the T6SS expression by Kp52145, 52145-Δhfq (hfq), 52145-ΔphoPQGB (phoPQ), 52145-ΔpmrAB (pmrAB), 52145-Δfur (fur), 52145-Δhn-s (hn-s), 52145-ΔrpoS (rpoS), 52145-ΔrpoN (rpoN), 52145-ΔmgrB (mgrB), 52145-ΔmgrB-ΔphoPQGB (mgrB-phoPQ), 52145-ΔrcsB (rcsB), and 52145-ΔrcsB-ΔphoPQGB (rcsB-phoPQ) carrying the transcriptional fusion tssB::lucFF and grown in LB. Luminescence is expressed as relative light units (RLU). The data are presented as means ± the standard deviations (n = 3). *#, results are significantly different (P < 0.0001 [two-tailed t test]) from the results for Kp52145; ***, results are significantly different (P < 0.001 [two-tailed t test]) from the results for Kp52145. (B) Bacterial killing activity mediated by Kp52145, 52145-Δhfq (hfq), 52145-ΔphoPQGB (phoPQ), 52145-ΔpmrAB (pmrAB), 52145-Δfur (fur), 52145-Δhn-s (hn-s), 52145-ΔrpoS (rpoS), 52145-ΔrpoN (rpoN), 52145-ΔmgrB (mgrB), 52145-ΔmgrB-ΔphoPQGB (mgrB-phoPQ), 52145-ΔrcsB (rcsB), and 52145-ΔrcsB-ΔphoPQGB (rcsB-phoPQ) against E. coli MG1655. Mock, PBS-treated E. coli. Number of recovered target cells following 6 h incubation in LB is indicated. The data are presented as means ± the standard deviations (n = 3). ***, results are significantly different (P < 0.001 [two-tailed t test]) from the results for Kp52145.