Environmental factors, regulating cellular

The preceding sections have focused on the molecular aspects of evolution of enzyme efficiency, specificity, and regulation. Flowever, it is important to remember that enzymes evolve in a cellular context. Natural selection acts upon the fitness of the organism, which is a complicated function of properties such as growth rate, robustness to environmental perturbations, ability to construct a protective biofilm, resistance to toxins, or synthesis of secondary metabolites that impair competitors. The catalytic capabilities of enzymes, as well as the repertoire of enzymes maintained by individual species of microbes, have been shaped by these environmental factors over billions of years. 

FIGURE 3.3.1 Schematic representations of environmental factors that regulate cellular activities. 

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