Abstract: Phages are abundant and ubiquitous in nature, and are therefore important components of microbial communities. They can impact on host populations in several ways.The survival of phage populations is limited by the activity of soil bacteria. One of the most effective stragies for survival is the lysogenic cycle of temperate phages in soil. However,virulence seems a more successful strategy for phage populations in aquatic ecosystems. Phage mediated transfer of genetic elements(transduction)between bacterial cells, particularly with regard to the use of phages, is dealt with. Recently,the transdution has been demonstrated in nature and must contribute to evolutionary development of host populations.