Transformation is one of three basic mechanisms for genetic exchange in bacteria. Transformation may be either a natural process—that is, one that has evolved in certain bacteria—or it may be an artificial process whereby the recipient cells are forced to take up DNA by a physical, chemical, or enzymatic treatment. In both cases, exogenous DNA (DNA that is outside the host cell), is taken into a recipient cell where it is incorporated into the recipient genome, changing the genetic makeup of the bacterium.

Natural Transformation

Natural transformation is a physiological process that is genetically encoded in a wide range of bacteria. Most bacteria must shift their physiology in order to transform DNA; that is, they must become "competent" for taking up exogenous DNA. There appear to be two basic mechanisms by which bacteria can become competent for transformation. In some bacteria, including Streptococcus pneumoniae and Bacillus...