Early changes in bacterial envelopes after inhibition of peptidoglycan synthesis, as shown by the use of a fluorescent probe.

The probe 8-anilino-1-naphthalene sulphonate (ANS) showed increasing fluorescence with Bacillus subtilis metC lyt-2 cells taken from exponentially growing cultures treated with antibiotics that inhibit cell-wall peptidoglycan synthesis. This increase was due to the probe reaching hydrophobic cell constituents, probably membranes, and started within 30 min of the addition of the antibiotics. This corresponded to the time at which membrane function had been shown to be damaged. The increased fluorescence of the cells with ANS persisted after removal of the antibiotics.