Fig 4.

Growth curves. E. coli DW2 cells with or without a given expression plasmid were incubated in LB broth at 37°C. Overnight cultures were diluted by 5% with LB-G broth (A and C) or NaCl-removed LB-G (B and D) in the absence or presence of melibiose at a concentration of 0.4, 10, or 30 mM and shaken at 37°C. Cell optical density was monitored hourly at A₆₀₀ and averaged from 2 to 5 tests; error bars represent standard deviations.