9 Detection and use of transposons

Publisher Summary Transposable elementsare discrete sequences of DNA that can move from one genetic locus to another on the same or on a different repliconby a process of recombination called “transposition or translocation.” They are ubiquitous among bacteria and many different ones have been discovered. The size of these elements can vary markedly from one another and many different properties can be transposable. When a transposable elementcontains an accessory gene, encoding some marker, it is called a “transposon:” the terms “ transposable element” and “transposon” are often used interchangeably. The transposablemarkers may be antibiotic resistance determinants, toxins and other virulence factors, or metabolic functions. The perceived importance of drug resistance transposons best reflects the human interest in this class of transposon and the ease with which they can be detected and studied. Much more investigation is needed before a decision on this point can be made. However, the point is not trivial, because transposons give to bacterial DNA and, in particular, to bacterial plasmids an enormous genetic flexibility that is reflected in the adaptability displayed by bacteria to the alterations in their environment.