FIG. 1.

FDA-EB staining of bacilli from a 10-month-old H37Ra culture in various media. About 10⁷ to 10⁸ bacilli from the 10-month-old culture grown in 7H9 medium as a standing culture were incubated in 100-μl volumes of supernatant of the same culture (A), 7H9 medium (B), and ESPSN (C), respectively, for 2 days, at which point the status of the bacterial cells was assessed by FDA-EB staining and fluorescence microscopy.