Table 2.

CT produced by pIG in El Tor strains

Strain [relevant genotype]CT productiona in:
LBAKI medium
E7946 [wild-type]<0.012.3
Bah-2 (pIG) [RF]0.70.8
Bah-2 [CTXφ]<0.01<0.01
Bah-2-55 (pIG) [toxR]b0.80.8
E7946-55 [toxR]b<0.01<0.01
Bah-2 (pSL1) [ΔSphI]c0.010.08
  • a Cells were incubated in the medium indicated (supplemented with kanamycin for strains harboring pIG or pSL1) at 37°C. Toxin amounts are expressed in micrograms per unit of optical density at 600 nm. Values represent the averages of at least three independent experiments.

  • b [toxR], inactivatedtoxR gene.

  • c pSL1 is a derivative of pIG which contains a deletion of the SphI site in orfU.