Bacteriology & Antibiotics

Bacterial Genomics

Bacterial genomics is a scientific discipline that concerns the genome, encompassing the entire hereditary information, of bacteria. Bacterial genomics can, for example, be used to study bacterial evolution or outbreaks of bacterial infections. All living organisms contain DNA. This amazing macromolecule encodes all of the information needed to program the cell's activities including reproduction, metabolism and other specialized functions. The human genome is comprised of 23 pairs of linear chromosomes, and approximately 3000 megabases (Mb) of DNA, while the genome of the bacterium Escherichia coli consists of a single 4.6 Mb circular chromosome. By studying the genomes of bacteria we are able to better understand their metabolic capabilities, their ability to cause disease and also their capacity to survive in extreme environments. Many of the well-studied bacterial model organisms, such as E. coli, have a single circular chromosome. However, advances in molecular genetics have shown that bacteria possess more complex arrangements of their genetic material than just a single circular chromosome per cell. Some bacterial genomes are comprised of multiple chromosomes and/or plasmids and many bacteria harbor multiple copies of their genome per cell. During the last decade, great advances have been made in the study of bacterial genomes which is perhaps better described by the term bacterial genomics. The application of powerful techniques, such as pulsed-field gel electrophoresis of macro-restriction fragments of genomic DNA, has freed the characterisation of the chromosomes of many bacteria from the constraints imposed by classical genetic analysis. It is now possible to analyse the genome of virtually every microorganism by direct molecular methods and to construct detailed physical and gene maps.