Figure 1. Flow Cytometry of Hoechst-Stained, Fixed Bacterial Cells.

For each histogram, the x-axis shows fluorescence levels, which indicate the amount of DNA content per particle counted. The y-axis shows counts, which indicate the number of fluorescing particles or cells. Culture optical densities (OD ₆₀₀) are listed to the left of each corresponding histogram. o.n., overnight culture.

(A) E. coli (Column 1) and Gc (Column 2) growth curves under standard laboratory conditions. At mid-log phase, part of the culture was treated with rifampicin ( E. coli) or tetracycline (Gc). Genome equivalents were determined from the stationary phase and rif-treated E. coli and are shown on the x-axis. The dotted line represents the division line for sorting into higher and lower fluorescent populations.

(B) E. coli and gonococcal cultures grown to mid-log phase at 37 °C or 30 °C. Genome equivalents were determined from stationary phase and rif-treated E. coli as in (A).