The inhibitory activity on T3SS of P. aeruginosa PA14 is conserved in BDSF derivatives. (A) Effect of exogenous addition of 10 μM BDSF and its derivatives on T3SS genes expression, as determined by using PexsCEBA-lacZ fusion reporter strain. “T” means the fatty acids with trans configuration; while “C” means the fatty acids with cis configuration; number represents the carbon chain length. Their structures were listed in Table S1. (B) BDSF (C12) showed the strongest activity than its saturated isomer (S12) and trans-isomer (T12). Bacteria were grown in LB medium supplemented with 5 mM NTA to an OD600 of ~1.5. The data are the means of three repeats and error bars indicate the standard deviations.