FIG. 2.

The effect of overexpression of the high-copy-number tet(O) gene on the viability of C. jejuni over a period of 48 h. Shown are the growth curves, in the absence of tetracycline, of an isolate carrying the tet(O) gene on the chromosome (closed squares) and with 50 μg/ml of tetracycline (open squares), and the growth curve, in the absence of tetracycline, of an isolate that has a high copy number of the tet(O) gene (closed triangles) and with 50 μg of tetracycline/ml (open triangles). Viable bacterial counts were determined at time 0 and after 5, 22, 28, and 48 h of incubation. Mean values from triplicate measurements are shown. Bars indicate the standard deviations.