Microbes and Metabolism 17or breakdown, enter these central metabolic pathways. The focus is on degrada-
tion rather than metabolism in general, since this is the crux of bioremediation.
A description of the biological macromolecules which are lipids, carbohydrates,
nucleic acids and proteins are given in the appropriate figures (Figures 2.2–2.5).
Not all possible metabolic routes are present in the genome of any one organ-
ism. Those present are the result of evolution, principally of the enzymes which
catalyse the various steps, and the elements which control their expression.
However, an organism may have the DNA sequences, and so have the genetic
capability for a metabolic route even though it is not ‘switched on’. This is the
basis for the description of ‘latent pathways’ which suggests the availability of a
Figure 2.2 Lipids