The adaptive responses of Escherichia coli to a feast and famine existence.

Publisher Summary Escherichia coli (E. coli) is a creature adapted to its ecological niche. This chapter examines several aspects of its fitness for survival in the lower intestine and has shown that E. coli is designed for efficient growth in its high viscosity habitat with its sporadic nutrient input. Effective use of resources to produce functioning organisms implies that macromolecular synthesis is properly divided between structural and enzymic units on one hand and the means of production that include ribosomes and t-RNA on the other. In an expanding economy all elements must increase, but the manufacture of means of production themselves must be more sensitively geared to the rate of expansion than to the actual quantity of goods produced. E. coli are not constructed to be efficient at allocating resources for nucleic acid and protein synthesis from the point of view of an ideal, non-fluctuating continuous culture. An analysis of the efficiency of the transport machinery that allows E. coli to compete with its neighbors for carbon and nitrogen sources, growth factors, or trace elements is presented. It is concluded that the transport mechanisms for several compounds have evolved to the degree where diffusion through the viscous natural environment is limiting.