FIG. 4.

Expression of S. typhi and E. coli ompC-lacZ fusions in ΔompB mutant strains complemented with a homologous or heterologous ompB operon. Expression of S. typhi ompC-lacZ and E. coli ompC-lacZ fusions in S. typhi ΔompB and E. coli ΔompB strains complemented with the S. typhi ompB (pIM261) or E. coli ompB (pIM40) operon was measured after growth in medium A with or without 0.3 M NaCl (high or low osmolarity, respectively). β-Galactosidase activity was assayed from samples taken hourly from duplicate cultures. The data show the activity after 5 h of growth and represent the average of two different experiments.