TABLE 2.

β-Galactosidase expression levels

Strain or characteristicaβ-Galactosidase expressionb (Miller units)
JH39a9 ± 1.2
ΔftsEX210::Kan27 ± 5.3
ΔftsEX::Kan (grown in LB with 0.2 M NaCl)20 ± 3.5
ΔftsEX::Kan (grown in LB with 0.2 M glucose)17 ± 3.8
ftsE::Kana26 ± 5.8
ftsX::Kana17 ± 3.4
ΔftsEX::Kan lexA3 malB::Tn911 ± 1.1
ΔftsEX::Kan/pCL192028 ± 6.2
ΔftsEX::Kan/pMN8 (pftsQAZ)25 ± 5.6
ΔftsEX::Kan/pMN14 (pftsN)23 ± 3.7
ΔftsEX::Kan/pMN16 (psufI)25 ± 4.2
ΔsufI21::Kan12 ± 1.3
  • a Strain JH39 and its ftsE::Kan or ftsX::Kan mutant derivatives were obtained from K. Kreuzer (35). All the other strains are derivatives of JH39. lexA3 linked to malB::Tn9 was transduced from strain GJ2382 (6).

  • b The specific activity of β-galactosidase was determined (32) in each of the cultures grown to exponential phase in LB, and values are means of at least three independent experiments.