Defences against oxidative stress during starvation in bacteria.

It now seems clear that starvation adaptation is important for cells to initiate long-term survival under conditions of not only nutrient depletion but to develop resistance to other stresses, most notably oxidative stress. Clearly, oxidative stress is a condition likely to be perceived by many bacteria, for example, in the form of reactive oxygen species derived from metabolic processes or from near-UV exposure. We have found evidence for a large degree of overlap in the cell's use of global regulators to deal with both starvation and oxidative stress. Both SpoT and AI-2 signalling pathways are important regulators of starvation and stress adaptation as well as the alternative sigma factor, RpoE. We also present evidence that suggests that AI-2 signalling can mediate starvation adaptation at the molecular level by increasing the stability of the mRNAs so that cells are prepared for rapid response to nutrient addition. Moreover, such extracellular signals mediate intraspecies communication to enable enhanced survival and stress resistance of neighbouring bacterial cells. It is likely that bacteria rely on a suite of effects between cells and on transcription, translation and post-translationalprocesses, mediated by global regulators and signalling molecules, to meet their needs for growth and survival.