Expression of toxins arrests or delays growth upon induction, but none of the toxins is required for growth.

(A) WT and strains lacking single or (B) multiple TA loci grow similarly in rich media. (C) Induction of the toxins relE, relE-3, sehA, shpAB* or vapC arrested or delayed S. Typhimurium growth in broth. (D) Expression of corresponding antitoxins with toxins reduced the growth delay. For C and D, overnight cultures were diluted and grown at 37°C for 2 hours, exposed to L-arabinose (0.2%) at Time 0, and monitored by absorbance at OD600. Strains carrying plasmid pBAD33 or pBAD24 were used for comparison; only growth of the strain containing pBAD33 is shown because the two vector containing strains grew similarly. Mean of > 3 independent experiments are shown; error bars denote SEM.