membrane damaged = cell death? - (Dec/28/2009 )

Dear all,
I have the following question: when a bacterium has a damaged cell membrane, will this cell then die after a while or?

Is a damaged membrane the precursos to cell death or not?

I suppose it would depend on how damaged the cell membrane was. I would think that in many situations, the cell could repair it's membrane. Isn't that how competent cells work?

This is a deceptively complicated question. The answer (of course) depends on the organism but also on the life cycle and the nature of the stress. microgirl is right that sometimes a cell can repair a ruptured membrane. But, for instance, in E. coli a stationary phase cell will be much more likely to survival membrane damage than an exponential phase cell, partially because several stress response mechanisms are not present in E. coli until it matures to stationary phase. Other organisms are more resilient in exponential phase, however, so this isn't entirely true. Further, it matters whether the stress is removed or not -- if you apply a physical or chemical stress to rupture the membrane and then don't stop the stress, the organism is much more likely to die than if it is transiently shocked and then returned to normal conditions. This is because a ruptured cell will begin to lose its contents and, at the same time, cytotoxic chemicals now enter the cell... a sort of double-whammy. If you shock the cell and then return it to normal conditions, the damage stops and repair can begin -- even then, it's still a race against the clock. The preparation of spheroplasts involves almost entirely removing the cell wall of an organism, and while fragile, those organisms can survive. (link: http://en.wikipedia.org/wiki/Spheroplast)