Table 3.

Effects of phoPQ, medium composition, and iron on expression of a iviXVII::lac(pdu) fusion

iviXVII::lac derivativeβ-Galactosidase activity (U)a
pH 5.5, 0.05 mM Mg2+pH 7.0, 0.05 mM Mg2+pH 7.6, 10 mM Mg2+
−Iron+Iron−Iron+Iron−Iron+Iron
phoP+ 22252728827322
phoP102::Tn10d-Cm132161536113344
phoQ24 1110121513247
  • a Determined in cultures grown for 16 h in MOPS minimal medium at the given pH and Mg2+concentration in the presence or absence of 50 μM iron. Medium without iron added also contained the iron-chelating agent 2,2′-dipyridyl (0.03 mM). Data represent averages of three independent cultures with a standard deviation of <10% of the mean.