FIG. 4.

IPTG induction of lacZ from P_{pilA-lacO-RBS}-lacZ during development: specific activity of β-galactosidase expressed in DK12602 (P_{pilA-lacO-RBS}-lacZ) and DK12604 (P_{pilA-lacO-RBS}-lacZ, P_pilA-lacI) during development. Specific activities of β-galactosidase were determined in cells after exposure to starvation in MC7 buffer with or without 1 mM IPTG for different times. Symbols: ▴, DK12602; □, DK12604 with IPTG; ⋄, DK12604 without IPTG. The specific activities of β-galactosidase are expressed in nanomoles of o-nitrophenol produced from o-nitrophenol-β-d-galactoside per minute per milligram of protein. Each value is the average of the values from two independent experiments, and the error bars indicate standard deviations.