This is an interesting review paper that discuss the mechanisms behind the activation of bacteria from protective states such as dormancy and the more controversial viable- but-not-nonculturable (VNC) state.
This protective or non-dividing states adopted by bacteria under stress are very important in clinical setting since they seem to be responsible for the development of recalcitrant infections that leads to an increased patient’s morbidity and mortality.
Briefly, in 1998 Mukamolova et al. have introduced the concept of bacterial cytokine, characterizing the 17-kDa protein termed resuscitation-promoting factor (RPF) produced by Micrococcus luteus . Latter, it was found that this protein presented a sequence homology, despite weak, to lysosymes and lytic transglycosylase and, additionally, it was shown that peptidoglycan is used by this protein as a substract activating, this way, cells division and the inactivation of the non-growth state.
However, much more studies have to be done to understand all the mechanisms that lead to the emergence from protective to active states of growth.
Reference of the paper summarized above: