Horizontal gene transfer in bacteria: an ecological and evolutionary perspective

Abstract

In recent years, molecular genetics and genome analysis provided extensive evidence that gene loss and acquisition are likely to be the primary mechanisms by which bacteria genetically adapt to novel or changed environments and by which bacterial populations diverge and form separate, evolutionary distinct species. Three mechanisms of gene transfer have been identified in microorganisms: transformation, conjugation and transduction, but our knowledge concerning horizontal gene transfer in the environment was and still is very limited. Animal gut and in particular the rumen belong to the most complex microbial ecosystems. Conditions in the rumen potentially favour horizontal gene transfer with conjugation and transduction, due to large, diverse and dense bacterial and bacteriophage populations, however, there is very little evidence supporting theoretical assumptions. A brief review of current knowledge on horizontal gene transfer is presented with the emphasis on the available data and views concerning the process going on in the rumen.