Examples of growth curves in various conditions. For each case, two independent measurements (triangles and circles) are shown, demonstrating the reproducibility of the measurement. The origin of the time axis corresponds to 10 counts per second (cps). (a) Influence of chloramphenicol stress on the parental strain. Growth in a favorable environment (black), and supplemented with 0.2 μg/ml (magenta) and 1.2 μg/ml (cyan) chloramphenicol are shown. Inset: the growth rate, determined from these and similar data, against chloramphenicol concentration. (b) One mutant of the library (green) compared to the parental strain (black) in the favorable environment (solid symbols) and under chloramphenicol stress (open symbols). Inset: the growth rates of the parental strain and the mutant in the two environments. The data indicate a strong alleviation of the effect of this specific mutation under chloramphenicol stress.