Barriers to horizontal gene transfer by natural transformation in soil bacteria

Bacteria can utilize horizontally transferred DNA from other bacterial spec ies to adapt and evolve to their changing environments. Natural transformat ion is a process that allows bacteria, which are able to express a regulate d physiological state of competence, to take up and integrate free DNA from their surroundings. This uptake of DNA does not necessarily depend on DNA sequence thus, indicating the potential of gene transfer from diverged dono r organisms. Barriers active against such interspecies transfer are present at different phases of the transformation process. The functionality of th ese barriers will be discussed, and seen in relation to mechanisms that may enable bacterial cells to respond to environmental stress by adaptive evol ution.