Lysis of exponential cultures of B. subtilis follows the addition of
reagents that dissipate either the electrical or pH gradients of cellular membranes. Stationary-phase cells or cultures that have been inhibited in division by macromolecular-synthesis inhibitors also lyse when
uncoupling agents or
ionophores are added to the growth medium.
Autolysis occurs after brief
starvation for a
carbon source. Protoplasts are unaffected by
azide or other lysis-inducing agents. Electron-donating agents, such as
phenazine methosulfate and ascorbate, are effective in retarding
autolysis. The addition of an oxidizable
carbon source to starved and lysing cultures prevents their
autolysis. These results suggest that cellular lysis in B. subtilis and energized membrane are tightly coupled. The fluorescence intensity and the wavelength of maximal fluorescence of 8-anilino-1-naphthalene
sulfonic acid, when added to bacterial
suspensions, appear to be qualitatively related to the rate of cell lysis. Analyses show that
ATP limitations are probably not involved in the elicitation of lysis by
ionophores,
uncoupling agents or
starvation. Measurements of protonmotive forces in the lysis-prone cells suggest that a threshold force of more than 85 mV may be required to maintain cellular integrity. Lipoteichoic
acids,
polyelectrolytes such as
dextran sulfate or
phospholipids do not modify the rate of cellular lysis when added to
suspensions containing
azide or other
reagents that eliminate transmembrane protonmotive forces. We interpret the results to suggest that the in vivo control of
autolysin activity in B. subtilis is related to the energized membrane