Bacteria are immortal in the sense that their capacity for reproduction appears limitless
as long as the environment supports growth. However, this reproductive
ability is gradually lost upon famine conditions. The loss of reproductive ability is
one of the first signs of physiological deterioration and is followed by a collapse
of the membrane integrity. The underlying molecular mechanism behind this degenerative
change and decline is something of an enigma in bacteriology. Still, recent
analysis of the conditional deterioration of growth arrested Escherichia coli
cells has revealed interesting similarities with the aging process of higher organisms.
The similarities include oxidation of proteins and its target specificity, the
role of antioxidants and oxygen tension, and an apparent antagonism between reproduction
and survival activities. The analysis of the E. coli model system has
also revealed a novel culprit in the oxidation of proteins, i.e. an intimate link between
the fidelity of the translational apparatus and oxidative modification of proteins.
This review summarizes and evaluates the models of bacterial conditional
deterioration and relates them to contemporary theories of aging in higher organisms.