Physical as well as chemical responses are required to shifting conditions, and bacteria must anticipate both opportunity and hazard in their changing chemical environment. Evolution builds upon precedent, and the small genome size of bacteria makes it inevitable that different sets of responses have evolved in response to similar challenges. So analysis of the nutritional versatility of bacteria leads directly to a study of the origins of evolutionary diversity. If a single theme emerges from this recent research, it is the fluidity of biological systems. DNA, often heralded as the secure store of genetic information, can undergo programmed loss or change.
Enzymes can function despite seemingly major changes in their structure.
One transport system can compensate for loss of function in another. Complex metabolic transformations that might be harmful inside the cell can be achieved outside the cell membrane. Emerging from these investigations are strategies that have been successfully applied by bacteria over the ages and that form a repository of knowledge for design of bacteria to meet novel challenges. Gerischer, U., A. Segura, and L. N. Ornston. PcaU, transcriptional activator of genes for protocatechuate utilization in Acinetobacter.