Table 1.

Bacterial strains used.

Strains	Relevant genotype	Reference
BG687 a	+xylR, PxylA, cat	[12]
BG689 a	+xylR, PxylA ζY83C, cat	[12]
BG1127 a	+lacI, Phsp, spc, [pCB799, xylR, PxylA ε, cat]	[12]
BG1125 a,b	+lacI, Phsp ζ, spc, [pCB799, xylR, PxylA ε, cat]	[12]
BL21(DE3) c	+[pCB920, PT7 ζ gene, Pω ω and ε genes, bla]	This work

^a The B. subtilis strains are isogenic with BG214 (trpCE metA5 amyE1 ytsJ1 rsbV37 xre1 xkdA1 att^SPβ att^ICEBs1); ^b BG1125 cells bearing pCB799-borne ε gene were grown in MMS7 containing 0.005% Xyl to titrate basal expression of the wt ζ toxin; ^c E. coli BL21(DE3) genotype (ompT gal (λ DE3, int::lacI-Plac_UV5 T7 gene 1) fhuA2 (dcm) ΔhsdS).