Bioavailability of Energy and the Starvation State

An essential role for the Escherichia coli DnaK protein in starvation-induced thermotolerance, H2O2 resistance, and reductive division

“…Stationary-phase cells produced by nutrient deprivation (25) or nutrient excess (12) exhibit a distinctive rounded cell shape of reduced volume (33,37,45,46) and a generalized resistance to extremes of heat, oxidizing agents such as hydrogen peroxide (H 2 O 2 ), and sodium chloride (for reviews, see references 28 and 38). Starvation-induced resistance is dependent upon protein synthesis (25) and the regulons controlled by the alternative sigma factors 32 (24) and S (39), encoded by the rpoH and rpoS (katF) genes, respectively (for a review, see reference 36).…”

“…Stationary-phase cells assume a characteristic small and spherical cell morphology in a process termed reductive division (45). This morphological change is likely to involve the morphogene bolA (1) and ficA (26).…”

On the nature ofMycobacterium tuberculosis-latent bacilli

“…Higher bactericidal capacity of rifampicin in "intermittent" incubation [11] Bacillary survival in sealed cultures at 37uC after 12 yrs [12] Adaptation of bacilli to a low oxygen pressure [13][14][15] Higher resistance to stressful conditions in bacilli from stationary-phase cultures [16] Transcription of genes (e.g. SigF) related to the sporulation cascade in other bacteria, under stressful conditions [17][18][19] Dormant "noncultureable" bacilli can be "resuscitated" with phospholipids and a specific factor (Rpf) synthesised by growing bacilli [20][21][22][23][24] Experiments in animal models…”

“…Different authors have also demonstrated higher resistance against different stress conditions of bacilli in the stationary phase of their growth compared with bacilli growing exponentially [26]. The stationary phase in a conventional culture is known to appear when bacteria are starving due to a lack of nutrients or the accumulation of toxins generated by bacterial metabolism [16]. This resistance capacity observed in all bacteria might reflect some kind of adaptation to hostile conditions, such as the ones generated in partially activated macrophages.…”

“…It is difficult to explain why some of these cells have one or two bacilli inside. The answer may be that these bacilli withstand the bactericidal mechanisms by triggering a starvation response [16], thus stopping their growth. Taking into account that the immunity against M. tuberculosis seems to be directed against peptides synthesised by growing bacilli [49,50], it may be hypothesised that these bacilli may not be recognised by the immune system.…”