FIG. 2.

Growth of wild-type and Tc^r mutant strains in increasing concentrations of TET. A 2.5-μl portion of an overnight culture was used to inoculate 5 ml of Luria-Bertani broth containing the indicated concentration of TET. Cultures were grown for 16 h with shaking at 37°C, after which the A₆₀₀ was measured. TET (a 4-mg/ml solution in 50% ethanol) was stored for no more than a few weeks at −10°C. TET concentrations, in micrograms per milliliter, were as follows: 2 (filled bars), 4 (stippled bars), 6 (diagonally striped bars), and 8 (open bars).